User side load response method based on adjustment and control on temperature of load clusters

Abstract

Provided is a user side load response method based on adjustment and control on temperature of load clusters. The user side load response method includes: performing thermodynamic modeling on a temperature control load to obtain a temperature control model in direct load control; constructing a mapping quantity to describe the change state of a temperature control load relay switch; obtaining adjustable capacity of the temperature control load through the mapping quantity; introducing temperature control load clusters to solve the problem that control precision cannot satisfy condition requirements; and finally calculating the influence of each load cluster in different load cluster control schemes on comfort degree.

Claims

1. A user side load response method based on adjustment and control on temperature of load clusters, comprising: receiving, by a load aggregator, a dispatching command sent from a dispatching center at a time point t, wherein the dispatching command is an expected dispatchable capacity D.sub.f(t) at the time point t; performing calculation, by the load aggregator, to obtain an actual dispatchable capacity D(t) of a temperature control load at the time point t; obtaining a controlled temperature setting value θ.sub.ref of the temperature control load corresponding to the expected dispatchable capacity D.sub.ref(t), and obtaining a to-be-controlled temperature value θ.sub.t.sub.− of the temperature control load corresponding to the actual dispatchable capacity D(t); calculating, by the load aggregator, a temperature change quantity u(t) of the temperature control load at the time point t through θ.sub.ref−θ.sub.t.sub.−; dividing, by the load aggregator, a temperature control load group that participates in adjustment and control into a plurality of temperature control load clusters, and performing calculation to obtain a temperature change quantity u.sub.i(t) of each of the plurality of temperature control load clusters according to the temperature change quantity u(t); sending, by the load aggregator, temperature change quantity u.sub.i(t) of each of the plurality of temperature control load clusters, to temperature control loads in the each of the plurality of temperature control load clusters, receiving, by the temperature control loads in the each of the plurality of temperature control load clusters, the temperature change quantity u.sub.i(t) of each of the plurality of temperature control load clusters, and adjusting, by the temperature control loads in the each of the plurality of temperature control load clusters, actual dispatchable capacities D(t) of the temperature control loads in the each of the plurality of temperature control load clusters according to the temperature change quantity u.sub.i(t) of each of the plurality of temperature control load clusters, wherein the temperature control load group comprises a plurality of temperature control loads, wherein the dividing, by the load aggregator, the temperature control load group that participates in adjustment and control into the plurality of temperature control load clusters comprises: dividing the temperature control load group into the plurality of temperature control load clusters according to types of temperature control loads.

2. The user side load response method according to claim 1, wherein performing calculation, by the load aggregator, to obtain a temperature change quantity u.sub.i(t) of each of the plurality of temperature control load clusters according to the temperature change quantity u(t) comprises: $u_i\left(t\right)=\{\begin{array}{cc}\mathrm{floor}\left[\frac{u\left(t\right)}{\Delta u^{\prime }}\right]\Delta u^{\prime }& \mathrm{if}l>L\frac{\mathrm{mod}\left(u\left(t\right),\Delta u^{\prime }\right)}{\Delta u^{\prime }}\\ \mathrm{floor}\left[\frac{u\left(t\right)}{\Delta u^{\prime }}\right]\Delta u^{\prime }+\Delta u^{\prime }& \mathrm{if}l\le L\frac{\mathrm{mod}\left(u\left(t\right),\Delta u^{\prime }\right)}{\Delta u^{\prime }}\end{array},$ wherein floor[⋅] is a function which takes an integer value of [⋅], mod(⋅) represents a remainder of u(t)/Δu′, l represents a serial number of one of load clusters, L represents a number of the load clusters, and Δu′ represents a temperature adjustment precision of the temperature control loads.

3. The user side load response method according to claim 1, wherein switching-on powers of all the temperature control loads are the same, and the performing calculation, by the load aggregator, to obtain the actual dispatchable capacity D(t) of the temperature control load at the time point t comprises: $D\left(t\right)\approx \frac{1}{6}+\frac{1}{6}\mathrm{erf}\left[\frac{\mathrm{In}\left(1\right)-\mathrm{In}\left({\mu }_x\left(0\right)+{\mu }_{v}t\right)}{\sqrt{2}{\sigma }_{\mathrm{ref}}}\right]+\frac{1}{2}\times \underset{j=2}{\overset{\infty }{.Math.}}{\left(-1\right)}^{j+1}\mathrm{erf}\left[\frac{\mathrm{In}\left(j\right)-\mathrm{In}\left({\mu }_x\left(0\right)+{\mu }_{v}t\right)}{\sqrt{2}{\sigma }_{\mathrm{ref}}}\right],$ wherein output power P and equivalent thermal resistances R of all the temperature control loads are the same, an equivalent thermal capacity C follows logarithmic normal distribution and has In(C)˜N(μ.sub.C,σ.sub.C), wherein erf[⋅] is a gauss error function, μ.sub.x(t) is an average value of a change state mapping quantity x.sub.i(t) of a temperature control load relay switch at time point t, σ.sub.ref is a ratio of a variance to a mathematical expectation and has ${\sigma }_{\mathrm{ref}}=\frac{{\sigma }_C}{{\mu }_C},$ wherein μ.sub.C is a mathematical expectation of capacitance distribution, σ.sub.C represents a variance of the capacitance distribution, μ.sub.x(0) is an average value of a change state mapping quantity x.sub.i(0) of the temperature control load relay switch at an initial time, and μ.sub.v represents a mathematical expectation of a temperature change speed, and j is a positive integer.

4. The user side load response method according to claim 1, wherein the performing calculation, by the load aggregator, to obtain the actual dispatchable capacity D(t) of the temperature control load at the time point t comprises: wherein P is an output power of the temperature control load, R is an equivalent thermal resistance, C is an equivalent thermal capacity of the temperature control load and follows a logarithmic normal distribution, wherein a state switching period T of a temperature control load relay satisfies T≈2/μ.sub.v, a largest amplitude A(t) of D(t) decays with time and has 1−erf(1/z(t))≤A(t)≤erf(1/z(t)), wherein z(t)=2√{square root over (2)}σ.sub.ref(μ.sub.x(0)+μ.sub.vt−½), and the actual dispatchable capacity D(t) of the temperature control load is expressed as follows:
D(t)=D.sub.SS(θ.sub.ref)+L.sup.−1{G.sub.P(s)0.5/s} wherein L.sup.−1{⋅} represents an inverse Laplace transform, G.sub.P(s) is a transfer function of a second-order linear time-invariant system, D.sub.SS(θ) represents a dispatchable capacity of the temperature control load group when a temperature setting value θ is stable, θ.sub.ref represents a temperature setting value, σ.sub.ref is a ratio of a variance to a mathematical expectation, μ.sub.v represents a mathematical expectation of a temperature change speed, μ.sub.x(t) is an average value of a change state mapping quantity x.sub.i(t) of a temperature control load relay switch at time point t, and μ.sub.x(0) is an average value of a change state mapping quantity x.sub.i(0) of the temperature control load relay switch at an initial time.

5. The user side load response method according to claim 4, wherein the controlled temperature setting value θ.sub.ref of the temperature control load corresponding to the expected dispatchable capacity D.sub.ref(t) and the to-be-controlled temperature value θ.sub.t.sub.− of the temperature control load corresponding to the actual dispatchable capacity D(t) are obtained according to the following formulas: $G_p\left(s\right)=\frac{b_2{s}^2+b_{1}s+b_0}{s^2+2{\mathrm{\xi \omega }}_{n}s+{\omega }_n^2};$ $\xi =\frac{\ln \left(r\right)}{\sqrt{{\pi }^2+{\ln }^2\left(r\right)}};$ ${\omega }_n=\frac{{\mathrm{\pi \mu }}_v}{\sqrt{1-{\xi }^2}};$ $b_0=\frac{{\omega }_n^2\left(D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}+0.5\right)-D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right)\right)}{0.5};$ $b_1=0.5{\mu }_v+2D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right){\mathrm{\xi \omega }}_n$ $b_2=D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right);$ $r=\frac{.Math.\mathrm{erf}\left(\frac{1}{0.9+2\sqrt{2}{\sigma }_{\mathrm{ref}}}\right)-0.5.Math.}{.Math.\mathrm{erf}\left(\frac{1}{0.9}\right)-0.5.Math.};$ $D_{\mathrm{SS}}\left(\theta \right)={\left(1+\frac{\log \left(1+\frac{H}{{\theta }_a-\theta -H\text{/}2}\right)}{\log \left(1+\frac{H}{\mathrm{PR}+\theta -{\theta }_a-H\text{/}2}\right)}\right)}^{-1};$ wherein s is a complex variable, b.sub.0, b.sub.1 and b.sub.2 are coefficients of the complex variable, ξ represents a frequency domain transformation coefficient, ω.sub.n represents a frequency domain independent variable, D.sub.SS(θ) represents the dispatchable capacity of the temperature control load group when the temperature setting value θ is stable, θ.sub.ref represents the temperature setting value, H represents a temperature control interval and has H=θ.sub.+−θ.sub.−, θ represents the temperature value, and θ.sub.a represents an environment temperature.

6. The user side load response method according to claim 5, wherein the change state mapping quantity x.sub.i(t) of the ith temperature control load relay switch is expressed as:
x.sub.i(t)=x.sub.i.sup.0+v.sub.it; wherein $.Math.\frac{d{\theta }_i\left(t\right)}{\mathrm{dt}}.Math.\approx v_i=\frac{{\theta }_a-{\theta }_{\mathrm{ref}}}{C_i{R}_i},\mathrm{and}{x}_i^0=\{\begin{array}{cc}1+{\theta }_i\left(0\right)-{\theta }_{-}^{\mathrm{post}}& \mathrm{if}\frac{d{\theta }_i\left(0^{-}\right)}{\mathrm{dt}}>0\\ {\theta }_{+}^{\mathrm{post}}-{\theta }_i\left(0\right)& \mathrm{if}\frac{d{\theta }_i\left(0^{-}\right)}{\mathrm{dt}}<0\end{array};$ wherein θ.sub.i(t) represents a temperature value of an energy storage medium of an ith temperature control load at the time point t, v.sub.i represents a temperature change rate of the ith temperature control load at the time point t, C.sub.i represents an equivalent thermal capacity of the ith temperature control load, R.sub.i represents an equivalent thermal resistance of the ith temperature control load, x.sub.i.sup.0 represents a value of the state mapping quantity of the ith temperature control load relay switch at the initial time, θ.sub.+.sup.post and θ.sub.−.sup.post respectively represent an upper limit value and a lower limit value of the temperature after temperature control, θ.sub.i(0) represents an internal temperature of the load energy storage medium of the ith temperature control load at the initial time, and θ.sub.i(0.sup.−) represents an internal temperature of the load energy storage medium of the ith temperature control load at a moment before the initial time.

7. The user side load response method according to claim 6, wherein the temperature of the energy storage medium of each of temperature control loads satisfies the following formula: $\frac{d\theta \left(t\right)}{\mathrm{dt}}=-\frac{1}{\mathrm{CR}}\left[\theta \left(t\right)-{\theta }_a+m\left(t\right)\mathrm{RP}+w\left(t\right)\right];$ $m\left(t^{+}\right)=\{\begin{array}{cc}0& \mathrm{if}\theta \left(t\right)\le {\theta }_{-}+u\left(t\right)\\ 1& \mathrm{if}\theta \left(t\right)\ge {\theta }_{+}+u\left(t\right)\\ m\left(t\right)& \mathrm{else}\end{array};$ wherein θ(t) represents the temperature value of the energy storage medium of the temperature control load at the time point t, P is a constant output power when the temperature control load is switched on, w(t) represents an unpredictable thermal disturbing influence, m(t) represents relay states, m(t)=1 represents a switched-on state and m(t)=0 represents a switched-off state, t is time, θ.sub.+ represents an upper limit value of the temperature setting value before a load response; θ.sub.− represents a lower limit value of the temperature setting value before a load response, t.sup.+ represents a moment after the time point t, u(t) represents a change quantity of the temperature setting value at the time point t, and m(t.sup.+) represents a relay state at the moment after the time point t.

8. A user side load response method based on adjustment and control on temperature of load clusters, comprising: performing fundamental thermodynamic modeling, by a load aggregator, on a temperature control load, and establishing a temperature control model for directly controlling a temperature control load; constructing a mapping quantity, by the load aggregator, to describe a change state of a temperature control load relay switch; constructing a direct relation, by the load aggregator, between the mapping quantity and an adjustable capacity of the temperature control load; and dividing, by the load aggregator, a temperature control load group that participates in adjustment and control into a plurality of temperature control load clusters, and performing adjustment on temperature change quantity of each of the plurality of temperature control load clusters, wherein the temperature control load group comprises a plurality of temperature control loads, wherein the dividing, by the load aggregator, a temperature control load group that participates in adjustment and control into a plurality of temperature control load clusters, and performing adjustment on temperature change quantity of each of the plurality of temperature control load clusters comprises: sending, by the load aggregator, a dispatching command by a dispatching center, wherein the dispatching command is an expected dispatchable capacity D.sub.ref(t) at the time point t; calculating a temperature change quantity u(t) of a temperature control device at the time point t; dividing, by the load aggregator, a temperature control load group into L temperature control load clusters according to types of temperature control loads, wherein a temperature adjustment signal of each of the temperature control load clusters is u.sub.i(t), so that a rough temperature adjustment quantity Δu′ of each of the temperature control loads is within a realizable range, and the temperature adjustment signal u.sub.i(t) of each of the load cluster is calculated through the following formulas: $\begin{array}{cc}{u}_i\left(t\right)=\{\begin{array}{cc}\mathrm{floor}\left[\frac{u\left(t\right)}{\Delta u^{\prime }}\right]\Delta u^{\prime }& \mathrm{if}l>L\frac{\mathrm{mod}\left(u\left(t\right),\Delta u^{\prime }\right)}{\Delta u^{\prime }}\\ \mathrm{floor}\left[\frac{u\left(t\right)}{\Delta u^{\prime }}\right]\Delta u^{\prime }+\Delta u^{\prime }& \mathrm{if}l\le L\frac{\mathrm{mod}\left(u\left(t\right),\Delta u^{\prime }\right)}{\Delta u^{\prime }}\end{array}& \left(16\right)\end{array}$ floor[⋅] is a function which takes an integer value of [⋅]; mod(⋅) represents a remainder of u(t)/Δu′, l represents a serial number of one of the plurality of temperature control load clusters, and L represents a number of the plurality of temperature control load clusters; and sending, by the load aggregator, the temperature adjustment signal u.sub.i(t) of each of the load cluster, to temperature control loads in the each of the load cluster, receiving, by the temperature control loads in the each of the plurality of temperature control load clusters, the temperature change quantity u.sub.i(t) of each of the plurality of temperature control load clusters, and adjusting, by the temperature control loads in the each of the plurality of temperature control load clusters, actual dispatchable capacities D(t) of the temperature control loads in the each of the plurality of temperature control load clusters according to the temperature change quantity u.sub.i(t) of each of the plurality of temperature control load clusters.

9. The user side load response method according to claim 8, wherein the temperature control model for directly controlling the temperature control load is: $\begin{array}{cc}\frac{d\theta \left(t\right)}{\mathrm{dt}}=-\frac{1}{\mathrm{CR}}\left[\theta \left(t\right)-{\theta }_a+m\left(t\right)\mathrm{RP}+w\left(t\right)\right]\mathrm{and}m\left(t^{+}\right)=\{\begin{array}{cc}0& \mathrm{if}\theta \left(t\right)\le {\theta }_{-}+u\left(t\right)\\ 1& \mathrm{if}\theta \left(t\right)\ge {\theta }_{+}+u\left(t\right)\\ m\left(t\right)& \mathrm{else}\end{array};& \left(1\right)\end{array}$ wherein θ′(t) represents a temperature value of an energy storage medium of the temperature control load at time point t, θ.sub.a represents an environment temperature, C and R respectively represent an equivalent thermal capacity and an equivalent thermal resistance of the temperature control load, P represents a constant output power when the temperature control load is switched on, w(t) represents an unpredictable thermal disturbing influence, m(t) represents relay states, m(t)=1 represents a switched-on state and m(t)=0 represents a switched-off state, t represents time, θ.sub.+ represents an upper limit value of a temperature setting value before a load response, θ.sub.− represents a lower limit value of the temperature setting value before the load response, t.sup.+ represents a moment after the time point t, u(t) represents a change quantity of the temperature setting value at the time point t, and m(t.sup.+) represents a relay state at the moment after the time point t.

10. The user side load response method according to claim 8, wherein the mapping quantity of a change state of the ith temperature control load relay switch x.sub.i(t) is expressed as:
x.sub.i(t)=x.sub.i.sup.0+v.sub.it  (2); wherein $\begin{array}{cc}.Math.\frac{d{\theta }_i\left(t\right)}{\mathrm{dt}}.Math.\approx v_i=\frac{{\theta }_a-{\theta }_{\mathrm{ref}}}{C_i{R}_i};& \left(3\right)\\ x_i^0=\{\begin{array}{cc}1+{\theta }_i\left(0\right)-{\theta }_{-}^{\mathrm{post}}& \mathrm{if}\frac{d{\theta }_i\left(0^{-}\right)}{\mathrm{dt}}>0\\ {\theta }_{+}^{\mathrm{post}}-{\theta }_i\left(0\right)& \mathrm{if}\frac{d{\theta }_i\left(0^{-}\right)}{\mathrm{dt}}<0\end{array};& \left(4\right)\end{array}$ wherein θ.sub.i(t) represents a temperature value of the energy storage medium of an ith temperature control device at the time point t, v.sub.i represents a temperature change rate of the ith temperature control device at the time point t, θ.sub.ref represents a temperature setting value, C.sub.i represents an equivalent thermal capacity of the ith temperature control device, R.sub.i represents an equivalent thermal resistance of the ith temperature control device, x.sub.i.sup.0 represents a value of mapping quantity of the ith temperature control device at an initial time, θ.sub.+.sup.post and θ.sub.−.sup.post respectively represent an upper limit value and a lower limit value of the temperature after temperature control, θ.sub.i(0) represents an internal temperature of the energy storage medium of the ith temperature control device at the initial time, and θ.sub.i(0.sup.−) represents an internal temperature of the energy storage medium of the ith temperature control device at the moment before the initial time.

11. The user side load response method according to claim 10, wherein in condition that switching-on powers of all of temperature control loads are the same, an actual dispatchable capacity D(t) of the temperature control load is calculated by the following formulas: $\begin{array}{cc}D\left(t\right)=\frac{\mathrm{Pr}\left[x\left(t\right)<1\right]}{3}+\underset{k=1}{\overset{\infty }{.Math.}}\mathrm{Pr}\left[x\left(t\right)<2k+1\right]-\mathrm{Pr}\left[x\left(t\right)<2k\right];& \left(5\right)\end{array}$ wherein Pr[⋅] is a probability operator indicating a probability value of satisfying [⋅], k is a positive integer, and x(t) represents a set of the mapping quantity x.sub.i (t) of the temperature control device.

12. The user side load response method according to claim 11, wherein in condition that output power P and equivalent thermal resistances R of all the temperature control loads are the same, the equivalent thermal capacity C follows a logarithmic normal distribution and has In(C)˜N(μ.sub.C,σ.sub.C), the actual dispatchable capacity D(t) of the temperature control load can be approximatively estimated as: in condition that $\begin{array}{cc}{\sigma }_{\mathrm{ref}}=\frac{{\sigma }_C}{{\mu }_C},& \\ D\left(t\right)\approx \frac{1}{6}+\frac{1}{6}\mathrm{erf}\left[\frac{\mathrm{In}\left(1\right)-\mathrm{In}({\mu }_x\left(0\right)+{\mu }_v\left(t\right)}{\sqrt{2}{\sigma }_{\mathrm{ref}}}\right]+\frac{1}{2}\times \underset{j=2}{\overset{\infty }{.Math.}}{\left(-1\right)}^{j+1}\mathrm{erf}\left[\frac{\mathrm{In}\left(j\right)-\mathrm{In}\left({\mu }_x\left(0\right)+{\mu }_{v}t\right)}{\sqrt{2}{\sigma }_{\mathrm{ref}}}\right];& \left(6\right)\end{array}$ wherein erf[⋅] is a gauss error function, and μ.sub.x(t) is an average value of the mapping quantity x of the temperature control device at the time point t, σ.sub.ref is a ratio of a variance to a mathematical expectation, and μ.sub.C is a mathematical expectation of capacitance distribution, σ.sub.C represents a variance of capacitance distribution, μ.sub.x(0) is an average value of the mapping quantity x of the temperature control device at the initial time, μ.sub.v represents a mathematical expectation of a temperature change speed, and j is a positive integer.

13. The user side load response method according to claim 12, wherein R, P and C follow the logarithmic normal distribution, a state switching period time T of the temperature control load relay satisfies T≈2/μ.sub.v, a largest amplitude A(t) of D(t) decays with time and has; 1−erf (1/z(t))≤A(t)≤erf(1/z(t), wherein z(t)=2√{square root over (2)}σ.sub.ref(μ.sub.x(0)+μ.sub.vt−½), and the actual dispatchable capacity D(t) of the temperature control load is expressed as follows:
D(t)=D.sub.SS(θ.sub.ref)+L.sup.−1{G.sub.P(s)0.5/s}  (7); wherein L.sup.−1{⋅} represents an inverse Laplace transform, and G.sub.P(s) is a transfer function of a second-order linear time-invariant system, $\begin{array}{cc}{G}_p\left(s\right)=\frac{b_2{s}^2+b_{1}s+b_0}{s^2+2{\mathrm{\xi \omega }}_{n}s+{\omega }_n^2}& \left(8\right)\\ \xi =\frac{\ln \left(r\right)}{\sqrt{{\pi }^2+{\ln }^2\left(r\right)}};& \left(9\right)\\ {\omega }_n=\frac{{\mathrm{\pi \mu }}_v}{\sqrt{1-{\xi }^2}};& \left(10\right)\\ b_0=\frac{{\omega }_n^2\left(D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}+0.5\right)-D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right)\right)}{0.5};& \left(11\right)\\ b_1=0.5{\mu }_v+2D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right){\mathrm{\xi \omega }}_n;& \left(12\right)\\ b_2=D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right);& \left(13\right)\\ r=\frac{.Math.\mathrm{erf}\left(\frac{1}{0.9+2\sqrt{2}{\sigma }_{\mathrm{ref}}}\right)-0.5.Math.}{.Math.\mathrm{erf}\left(\frac{1}{0.9}\right)-0.5.Math.};& \left(14\right)\\ D_{\mathrm{SS}}\left(\theta \right)={\left(1+\frac{\log \left(1+\frac{H}{{\theta }_a-\theta -H\text{/}2}\right)}{\log \left(1+\frac{H}{\mathrm{PR}+\theta -{\theta }_a-H\text{/}2}\right)}\right)}^{-1};& \left(15\right)\end{array}$ wherein s is a complex variable, and b.sub.0, b.sub.1 and b.sub.2 are coefficients of the complex variable; ξ represents a frequency domain transformation coefficient, ω.sub.n represents a frequency domain independent variable, D.sub.SS(θ) represents a dispatchable capacity of the temperature control load group when a temperature setting value θ is stable, θ.sub.ref represents a temperature setting value, H represents a temperature control interval and has H=θ.sub.+−θ.sub.−, and θ represents a temperature value.

14. The user side load response method according to claim 13, wherein the calculating, by the load aggregator, a temperature change quantity u(t) of a temperature control device at the time point t comprise: calculating an actual dispatchable capacity D(t) of the temperature control device at the time point t according to a formula (6) or a formula (7), obtaining a controlled temperature setting value of the temperature control load θ.sub.ref corresponding to the expected dispatchable capacity D.sub.ref(t) and a to-be-controlled temperature value θ.sub.t.sub.− of the temperature control load corresponding to the actual dispatchable capacity D(t) according to the expected dispatchable capacity D.sub.ref(t) and the actual dispatchable capacity D(t) and by use of formulas (8-15) and by performing a Laplace transformation, and calculating the temperature change quantity u(t) of the temperature control device at the time point t through θ.sub.ref−θ.sub.t.sub.−.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a flow chart illustrating a user side load response method in the present disclosure;

(2) FIG. 2 is a load adjustment characteristic curve when a standard variance of an equivalent thermal capacity in a situation 1 is 0.5;

(3) FIG. 3 is a load adjustment characteristic curve when a standard variance of an equivalent thermal capacity in a situation 1 is 0.2;

(4) FIG. 4 is a load adjustment characteristic curve when a standard variance of an equivalent thermal capacity in a situation 1 is 0.1;

(5) FIG. 5 is a load adjustment characteristic curve when a standard variance of an equivalent thermal capacity in a situation 1 is 0.05;

(6) FIG. 6 is a load adjustment characteristic curve of various different standard variances in a situation 2;

(7) FIG. 7 is an internal control model of a load;

(8) FIG. 8 is a curve of an aggregation control dispatchable capacity obtained when precision of a load sensor is 0.05 degree;

(9) FIG. 9 is a curve of an aggregation control dispatchable capacity obtained when precision of a load sensor is 0.5 degree; and

(10) FIG. 10 is a curve of an aggregation control dispatchable capacity controlled by load clusters.

DETAILED DESCRIPTION

(11) The present disclosure is further described below in combination with drawings. The following embodiments are merely used for explaining the technical solution of the present disclosure more clearly, not used for limiting the protection scope of the present disclosure.

(12) As shown in FIG. 1, a user side load response method based on adjustment and control on load clusters includes the steps:

(13) In step 1, fundamental thermodynamic modeling on a temperature control load is performed, and a temperature control model directly controlled by loads is established.

(14) The temperature control load is abstracted as a thermodynamic model and is abstracted to be formed by two parts: a constant power output device and a relay according to the actual working situation of the temperature control load. The relay has two states indicated by m(t). When the relay is in a switched-on state, the constant power output device outputs constant power, and the temperature of the energy storage medium of the temperature control load is adjusted. When the relay is in a switched-off state, the constant power output device does not output power, and the temperature of the energy storage medium changes following thermodynamic law. The formula of the temperature θ(t) of the energy storage medium is:

(15) $\frac{d\theta \left(t\right)}{\mathrm{dt}}=-\frac{1}{\mathrm{CR}}\left[\theta \left(t\right)-{\theta }_a+m\left(t\right)\mathrm{RP}+w\left(t\right)\right];$$\begin{array}{cc}m\left(t^{+}\right)=\{\begin{array}{cc}0& \mathrm{if}\theta \left(t\right)\le {\theta }_{-}+u\left(t\right)\\ 1& \mathrm{if}\theta \left(t\right)\ge {\theta }_{+}+u\left(t\right)\\ m\left(t\right)& \mathrm{else}\end{array}.& \left(1\right)\end{array}$

(16) Where θ(t) represents a temperature value of an energy storage medium of the temperature control load at time point t, θ.sub.a represents an environment temperature, C and R respectively represent an equivalent thermal capacity and an equivalent thermal resistance of the temperature control load, P represents a constant output power when the temperature control load is switched on, w(t) represents an unpredictable thermal disturbing influence, m(t) represents relay states, m(t)=1 represents a switched-on state and m(t)=0 represents a switched-off state, t represents time, θ.sub.+ represents an upper limit value of a temperature setting value before a load response, θ.sub.− represents a lower limit value of the temperature setting value before the load response, t.sup.+ represents a moment after the time point t, m(t.sup.+) represents a relay state at the moment after the time point t, and u(t) represents a change quantity of the temperature setting value at the time point t.

(17) In step 2, a mapping quantity to describe a change state of a temperature control load relay switch is constructed. the mapping quantity of a change state of the ith temperature control load relay switch is set as x.sub.i(t), and a direct relation between the adjustable capacity D(t) of the temperature control load and the mapping quantity x.sub.i(t) is defined.

(18) The mapping quantity of a change state of the ith temperature control load relay switch is expressed by x.sub.i(t), i is a positive integer, and the x.sub.i(t) is expressed as follows:

(19) $\begin{array}{cc}{x}_i\left(t\right)=x_i^0+v_{i}t.\mathrm{Where}& \left(2\right)\\ .Math.\frac{d{\theta }_i\left(t\right)}{\mathrm{dt}}.Math.\approx v_i=\frac{{\theta }_a-{\theta }_{\mathrm{ref}}}{C_i{R}_i};& \left(3\right)\\ x_i^0=\{\begin{array}{cc}1+{\theta }_i\left(0\right)-{\theta }_{-}^{\mathrm{post}}& \mathrm{if}\frac{d{\theta }_i\left(0^{-}\right)}{\mathrm{dt}}>0\\ {\theta }_{+}^{\mathrm{post}}-{\theta }_i\left(0\right)& \mathrm{if}\frac{d{\theta }_i\left(0^{-}\right)}{\mathrm{dt}}<0\end{array}.& \left(4\right)\end{array}$

(20) Where θ.sub.i(t) represents a temperature value of the energy storage medium of an ith temperature control device at the time point t, v.sub.i represents a temperature change rate of the ith temperature control device at the time point t, θ.sub.ref represents a temperature setting value, C.sub.i represents an equivalent thermal capacity of the ith temperature control device, R.sub.i represents an equivalent thermal resistance of the ith temperature control device, x.sub.i.sup.0 represents a value of mapping quantity of the ith temperature control device at an initial time, θ.sub.+.sup.post and θ.sub.−.sup.post respectively represent an upper limit value and a lower limit value of the temperature after temperature control, θ.sub.i(0) represents an internal temperature of the energy storage medium of the ith temperature control device at the initial time, and θ.sub.i(0.sup.−) represents an internal temperature of the energy storage medium of the ith temperature control device at the moment before the initial time. The temperature adjustment deviation of the temperature control device set in the embodiment is 0.5 degree, so that θ.sub.+−θ.sub.−=1 and θ.sub.+.sup.post−θ.sub.−.sup.post=1.

(21) When x.sub.i(t) reaches an integer value, the control state of the temperature control load changes once, i.e., the switched-on state of the relay is changed into the switched-off state, or the switched-off state of the relay is changed into the switched-on state. In the course that x.sub.i(t) changes into an even number from an odd number, the temperature control load relay is in the switched-off state, i.e., in the time m(t)=0, and in the course that x.sub.i(t) changes into an odd number from an even number, the temperature control load relay is in the switched-on state, i.e., that in the time, m(t)=1.

(22) The size of the adjustable capacity of the temperature control load is expressed by D(t), the relation between the size of the adjustable capacity and the mapping quantity x.sub.i(t) is estimated as follows (the mapping quantity of a certain temperature control device is not specifically indicated below), and the set of the mapping quantity x.sub.i(t) of the temperature control device is expressed by x(t). In condition that the switched-on powers of all the temperature control loads are the same, the largest load change situation can be expressed by the value of the largest load capacity after per-unit value normalization treatment and can be equal to a probability value D(t). The largest power is outputted when D(t) is equal to 1. All the temperature control loads are switched on, and the adjustable capacity is the largest. The calculation formula of D(t) is as follows:

(23) $\begin{array}{cc}D\left(t\right)=\frac{\mathrm{Pr}\left[x\left(t\right)<1\right]}{3}+\underset{k=1}{\overset{\infty }{.Math.}}\mathrm{Pr}\left[x\left(t\right)<2k+1\right]-\mathrm{Pr}\left[x\left(t\right)<2k\right].& \left(5\right)\end{array}$

(24) Where Pr[⋅] is a probability operator indicating a probability value of satisfying [⋅], k is a positive integer.

(25) In step 3, two situations exist. The first situation: in condition that output power P and equivalent thermal resistances R of all the temperature control loads are the same, the equivalent thermal capacity C follows a logarithmic normal distribution and has In(C)˜N(μ.sub.C,σ.sub.C), and D(t) can be approximatively estimated as: in condition that

(26) $\begin{array}{cc}{\sigma }_{\mathrm{ref}}=\frac{{\sigma }_C}{{\mu }_C},& \\ D\left(t\right)\approx \frac{1}{6}+\frac{1}{6}\mathrm{erf}\left[\frac{\mathrm{In}\left(1\right)-\mathrm{In}\left({\mu }_x\left(0\right)+{\mu }_{v}t\right)}{\sqrt{2}{\sigma }_{\mathrm{ref}}}\right]+\frac{1}{2}\times \underset{j=2}{\overset{\infty }{.Math.}}{\left(-1\right)}^{j+1}\mathrm{erf}\left[\frac{\mathrm{In}\left(j\right)-\mathrm{In}\left({\mu }_x\left(0\right)+{\mu }_{v}t\right)}{\sqrt{2}{\sigma }_{\mathrm{ref}}}\right].& \left(6\right)\end{array}$

(27) Where erf[⋅] is a gauss error function, and μ.sub.x(t) is an average value of the mapping quantity x of the temperature control device at the time point t, σ.sub.ref is a ratio of a variance to a mathematical expectation, and μ.sub.C is a mathematical expectation of capacitance distribution, σ.sub.C represents a variance of capacitance distribution, μ.sub.x(0) is an average value of the mapping quantity x of the temperature control device at the initial time, μ.sub.v represents a mathematical expectation of a temperature change speed, and j is a positive integer.

(28) R, P and C follow the logarithmic normal distribution, a state switching period time T of the temperature control load relay satisfies T≈2/μ.sub.v, a largest amplitude A(t) of D(t) decays with time and has; 1−erf(1/z(t))≤A(t)≤erf(1/z(t), wherein z(t)=2√{square root over (2)}σ.sub.ref(μ.sub.x(0)+μ.sub.vt−½), and the actual dispatchable capacity D(t) of the temperature control load is expressed as follows:
D(t)=D.sub.SS(θ.sub.ref)+L.sup.−1{G.sub.P(s)0.5/s}  (7).

(29) Where L.sup.−1{⋅} represents an inverse Laplace transform, and G.sub.P(s) is a transfer function of a second-order linear time-invariant system.

(30) $\begin{array}{cc}{G}_p\left(s\right)=\frac{b_2{s}^2+b_{1}s+b_0}{s^2+2{\mathrm{\xi \omega }}_{n}s+{\omega }_n^2};& \left(8\right)\\ \xi =\frac{\ln \left(r\right)}{\sqrt{{\pi }^2+{\ln }^2\left(r\right)}};& \left(9\right)\\ {\omega }_n=\frac{{\mathrm{\pi \mu }}_v}{\sqrt{1-{\xi }^2}};& \left(10\right)\\ b_0=\frac{{\omega }_n^2\left(D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}+0.5\right)-D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right)\right)}{0.5};& \left(11\right)\\ b_1=0.5{\mu }_v+2D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right){\mathrm{\xi \omega }}_n;& \left(12\right)\\ b_2=D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right);& \left(13\right)\\ r=\frac{.Math.\mathrm{erf}\left(\frac{1}{0.9+2\sqrt{2}{\sigma }_{\mathrm{ref}}}\right)-0.5.Math.}{.Math.\mathrm{erf}\left(\frac{1}{0.9}\right)-0.5.Math.};& \left(14\right)\\ D_{\mathrm{SS}}\left(\theta \right)={\left(1+\frac{\ln \left(1+\frac{H}{{\theta }_a-\theta -H\text{/}2}\right)}{\ln \left(1+\frac{H}{\mathrm{PR}+\theta -{\theta }_a-H\text{/}2}\right)}\right)}^{-1}.& \left(15\right)\end{array}$

(31) Where H represents a temperature control interval and has H=θ.sub.+−θ.sub.−, s is a complex variable, and b.sub.0, b.sub.1 and b.sub.2 are coefficients of the complex variable; ξ represents a frequency domain transformation coefficient, ω.sub.n represents a frequency domain independent variable. r is a symbol established for concision of a formula and does not have special actual meaning, D.sub.SS(θ) represents a dispatchable capacity of the temperature control load group when a temperature setting value θ is stable, θ.sub.ref represents a temperature setting value, and θ represents a temperature value. The internal control structure of the load is shown in FIG. 7, where G.sub.d(s)=0.5/s and is a transfer function of the expected dispatchable capacity D.sub.ref(t) at time point t. The whole response process or control process is described as follows in combination with FIG. 7.

(32) A dispatching command is sent by a dispatching center, and the dispatching command is an expected dispatchable capacity D.sub.ref(t) at the time point t. An actual dispatchable capacity D(t) of the temperature control device at the time point t is calculated according to a formula (6) or a formula (7), a controlled temperature setting value θ.sub.ref corresponding to the expected dispatchable capacity D.sub.ref(t) and a to-be-controlled temperature value θ.sub.t.sub.− corresponding to the actual dispatchable capacity D(t) are obtained according to the expected dispatchable capacity D.sub.ref (t) and the actual dispatchable capacity D(t) and by use of formulas (8-15) and by performing a Laplace transformation. A temperature change quantity u(t) of the temperature control device at the time point t is calculated through θ.sub.ref−θ.sub.t.sub.−, and then through step 4, the temperature change quantity (temperature adjustment signal) u.sub.i(t) of the load clusters can be calculated, so that the response (control) process can be completed.

(33) In step 4, in accordance with the defect that the precision of a temperature sensor of the temperature control load cannot reach the set value or the temperature control of a single temperature control load is limited, an adjustment strategy of the temperature control load clusters is introduced, thereby solving the problem of low response precision caused by parameter errors such as low precision of sensors.

(34) For the defect that the precision of the temperature sensor of the temperature control load cannot reach the set value or the temperature control of the single temperature control load is limited, a manner of adjusting the temperature change quantity of different temperature control devices through the temperature control load clusters is considered. The manner is performed through the following specific steps: when a unified temperature control command u(t), i.e., the temperature change quantity of the temperature control device at time point t, sent from the dispatching center or the load aggregator is received, the temperature control load group is divided into L temperature control load clusters according to the types of the temperature control loads, and the temperature control of each temperature control load cluster is u.sub.i(t), so that the rough temperature adjustment quantity Δu′ of each temperature control load is within a realizable range of the precision of the sensor (such as 0.5 degree), and the calculation expression of the temperature adjustment signal u.sub.i(t) of each load cluster is:

(35) $\begin{array}{cc}{u}_i\left(t\right)=\{\begin{array}{cc}\mathrm{floor}\left[\frac{u\left(t\right)}{\Delta u^{\prime }}\right]\Delta u^{\prime }& \mathrm{if}l>L\frac{\mathrm{mod}\left(u\left(t\right),\Delta u^{\prime }\right)}{\Delta u^{\prime }}\\ \mathrm{floor}\left[\frac{u\left(t\right)}{\Delta u^{\prime }}\right]\Delta u^{\prime }+\Delta u^{\prime }& \mathrm{if}l\le L\frac{\mathrm{mod}\left(u\left(t\right),\Delta u^{\prime }\right)}{\Delta u^{\prime }}\end{array}.& \left(16\right)\end{array}$

(36) Where floor[⋅] is a function which takes an integer value of [⋅]; mod(⋅) represents a remainder of u(t)/Δu′, l represents a serial number of one of load clusters, and L represents a number of the load clusters.

(37) According to one embodiment of the present disclosure, a total of 10000 temperature control load clusters are selected. If all the temperature control load clusters respond to the response command sent from the dispatching center, the dispatching command i.e., the expected dispatchable capacity D.sub.ref(t) at time point t, is sent from the dispatching center at time point t; the actual dispatchable capacity D(t) of the temperature control device in the region is calculated by the load aggregator, and the adjustment temperature u.sub.i(t) of each load cluster is calculated through the algorithm of the present disclosure and is sent to each temperature control device, so that the response process is completed. The response parameters of the temperature control load clusters are shown in Table 1.

(38) TABLE-US-00001 TABLE 1 Response Parameter Table of Temperature Control Load Clusters Variable Value Remarks Equivalent 2° C./KW A definite value is taken in the situation thermal 1 μ.sub.R = 2° C./KW in the situation 2 resistance R Equivalent 10° C./KW μ.sub.c = 10° C./KW in thermal situation 1 and situation 2 capacity C Output power P 14 KW A definite value is taken in the situation 1, P = 14 KW in the situation 2 Lower limit set 19.5° C. temperature θ.sub.− Upper limit set 20.5° C. temperature θ.sub.+ Outdoor 32° C. temperature θ.sub.α

(39) Remarks are as follows.

(40) Situation 1: the equivalent thermal capacity C follows a logarithmic normal distribution when the output power P and the equivalent thermal resistances R of all the temperature control loads are the same.

(41) Situation 2: R, P and C follow a logarithmic normal distribution, considering the equivalent thermal resistances R and the output powers P of the temperature control loads are considered not to be the same in the actual situation.

(42) For the situation 1, equivalent thermal resistance R satisfies R=2° C./KW, the mathematical expectation of the distribution of the equivalent capacitance satisfies μ.sub.c=10° C./KW, and the output power P of the temperature control load satisfies P=14 KW. The variances of the logarithmic normal distribution of different equivalent heat capacities are substituted into a computer, and the adjustable margin of the load is calculated and is compared with an adjustable margin curve of an actual load.

(43) The rate of the variance to the mathematical expectation satisfies

(44) ${\sigma }_{\mathrm{ref}}=\frac{{\sigma }_C}{{\mu }_C}=0.5,$
when the standard variance σ.sub.C=5 KW/° C. of the equivalent thermal capacity is taken, and the rate is substituted in the formula (6) to obtain the load adjustment characteristic curve when the standard variance of the equivalent thermal capacity in the situation 1 is 0.5, as shown in the FIG. 2, wherein the actual data indicates the curve of the actual load adjustment capacity D(t).

(45) The probability value D(t) of the load is increased when the variance σ.sub.C of the equivalent thermal capacity of the temperature control load is decreased, and the load adjustment characteristic curve is shown in the FIG. 3 when the standard variance of the equivalent thermal capacity in the situation is 0.2 in condition that

(46) 0${\sigma }_{\mathrm{ref}}=\frac{{\sigma }_C}{{\mu }_C}=0.2.$

(47) The load adjustment characteristic curve is shown in the FIG. 4 when the standard variance of the equivalent thermal capacity in the situation 1 is 0.1 in condition that

(48) ${\sigma }_{\mathrm{ref}}=\frac{{\sigma }_C}{{\mu }_C}=0.1.$

(49) The load adjustment characteristic curve is shown in the FIG. 5 when the standard variance of the equivalent thermal capacity in the situation 1 is 0.05 in condition that

(50) ${\sigma }_{\mathrm{ref}}=\frac{{\sigma }_C}{{\mu }_C}=0.05.$

(51) For the situation 2, i.e., the mathematical expectation of the equivalent thermal resistance satisfies μ.sub.R=2° C./KW, the mathematical expectation of the equivalent thermal capacity satisfies μ.sub.C=10° C./KW, and the mathematical expectation of the load power satisfies P=14 KW.

(52) $H={\theta }_{+}-{\theta }_{-}=1;$$D_{\mathrm{SS}}\left(\theta \right)={\left(1+\frac{\ln \left(1+\frac{H}{{\theta }_a-\theta -H\text{/}2}\right)}{\ln \left(1+\frac{H}{\mathrm{PR}+\theta -{\theta }_a-H\text{/}2}\right)}\right)}^{-1}={\left(1+\frac{\ln \left(1+\frac{1}{32-\theta -0.5}\right)}{\ln \left(1+\frac{1}{28+32-\theta -0.5}\right)}\right)}^{-1}={\left(1+\frac{\ln \left(1+\frac{1}{31.5-\theta }\right)}{\ln \left(1+\frac{1}{59.5-\theta }\right)}\right)}^{-1};$$b_2=D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right)={\left(1+\frac{\ln \left(1+\frac{1}{31.5-20}\right)}{\ln \left(1+\frac{1}{59.5-20}\right)}\right)}^{-1}=0.2307;$${\mu }_v=\mathrm{mean}.Math.\frac{d{\theta }_i\left(t\right)}{\mathrm{dt}}.Math.\approx \mathrm{mean}\left(v_i\right)=\frac{{\theta }_a-{\theta }_{\mathrm{ref}}}{\mathrm{CR}}=\frac{32-20}{20}=0.6;$$\mathrm{If}\xi =0.259,{\omega }_n=0.033,\mathrm{then}{t}_s=4.6\text{/}{\mathrm{\xi \omega }}_n=525\left(\min \right),b_1=0.5{\mu }_v+2D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right){\mathrm{\xi \omega }}_n=0.4525,b_0=\frac{{\omega }_n^2\left(D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}+0.5\right)-D_{\mathrm{SS}}\left({\theta }_{\mathrm{ref}}\right)\right)}{0.5}=\frac{{0.033}^2\left(0.2906-0.2307\right)}{0.5}\approx 0.000063294.$

(53) When

(54) $G_p\left(s\right)=\frac{b_2{s}^2+b_{1}s+b_0}{s^2+2{\mathrm{\xi \omega }}_{n}s+{\omega }_n^2}$
is substituted, then D(t)=D.sub.SS(θ.sub.ref)+L.sup.−1{G.sub.P(s)0.5/s} is substituted and t is substituted into z(t)=2√{square root over (2)}σ.sub.ref(μ.sub.x(0)+μ.sub.vt−½). According to 1−erf(1/z(t))≤A(t)≤erf(1/z(t), the amplitude of the probability value D(t) can be obtained, so that the load adjustment characteristic curve of various different standard variances in the situation 2 can be obtained, as shown in the FIG. 6. FIG. 6 includes 3 curves: an actual data curve, a simulation curve of manually inputted coefficients ξ, ω.sub.n, b.sub.0, b.sub.1, b.sub.2 and a simulation curve of coefficients ξ, ω.sub.n, b.sub.0, b.sub.1, b.sub.2 obtained through calculation of an algorithm in the present disclosure.

(55) Selecting different rough temperature adjustment quantities may influence the adjustment capacity of the temperature control loads, and an aggregation control dispatchable capacity curve can be obtained when the precision of the load sensor is 0.05 degrees through the internal control structure of the load in FIG. 7 and in combination with formulas (1) and (7-15) when a rough temperature adjustment quantity is taken, as shown in the FIG. 8.

(56) However, the dispatching curve may not be satisfied if the precision of the sensor is not high enough. When Δu′=0.5, the aggregation control dispatchable capacity curve is shown in the FIG. 9.

(57) The dispatching capacity continuously fluctuates, but cannot change along with the needed curve. However, due to the precision of the sensor and the limit of the temperature adjustment range of the temperature control load, requirements for dispatching precision are not satisfied possibly. Then favorable load response cannot be obtained, and at this moment, the load clusters are introduced to solve the problem.

(58) For example, the adjustable range of each temperature control load satisfies Δu′=0.5, but the control precision needs to satisfy Δu=0.05. If the group is divided into L=10 aggregation types, and when t=t.sub.m, u(t)=1.15, then according to

(59) $u_l\left(t\right)=\{\begin{array}{cc}\mathrm{floor}\left[\frac{u\left(t\right)}{\Delta u^{\prime }}\right]\Delta u^{\prime }& \mathrm{if}l>L\frac{\mathrm{mod}\left(u\left(t\right),\Delta u^{\prime }\right)}{\Delta u^{\prime }}\\ \mathrm{floor}\left[\frac{u\left(t\right)}{\Delta u^{\prime }}\right]\Delta u^{\prime }+\Delta u^{\prime }& \mathrm{if}l\le L\frac{\mathrm{mod}\left(u\left(t\right),\Delta u^{\prime }\right)}{\Delta u^{\prime }}\end{array}.$

(60) u.sub.l(t.sub.m)=1.15 for the first, the second and the third aggregation types, and u.sub.l(t.sub.m)=1.1 for the remaining seven aggregation types.

(61) The adjustable capacity curves controlled after the control load clusters are introduced is shown in FIG. 10.

(62) The present disclosure discloses a user side load response method based on adjustment and control on temperature of load clusters. Load control is achieved by adjusting the set temperature of temperature control load clusters, and requirements for a power grid side load response are satisfied. The user side load response method includes the steps: firstly, thermodynamic modeling is performed on a temperature control load to obtain a temperature control model in direct load control; a mapping quantity is constructed to describe the change state of the temperature control load relay switch; adjustable capacity of the temperature control load is obtained through the mapping quantity; and the temperature control load clusters are introduced to solve the problem that control precision cannot satisfy conditions. The present disclosure sufficiently considers the adjustment characteristics of the temperature control load and the adjustment characteristics of the temperature control load clusters, so that the requirements for the power grid side load response are satisfied. The parameter difference of the temperature control device is considered, so that the calculation of the adjustable capacity of the temperature control device can be more objective and practical. A load cluster control strategy is adopted, so that the temperature control load response precision can be improved.

(63) The above only describes preferred embodiments of the present disclosure. It should be noted that those ordinary skilled in the art can still make several improvements and variations on the premise of not departing from the technical principle of the present disclosure. These improvements and variations can also be regarded in the protection scope of the present disclosure.