Current pattern matching method for non-intrusive power load monitoring and disaggregation

Abstract

A harmonic-characteristics based current pattern matching method for the non-intrusive power load monitoring and disaggregation is provided in this present invention, on the basis of establishing the load signature database, which comprises electrical appliance registration and load state word space initialization, data acquisition and data preprocessing, feasible state word space search based on table looking-up, the optimal matching of current pattern, and display and output of the monitoring and disaggregation results. The method improves the accuracy of disaggregation, and can achieves exact identification of operating states of appliances, and also can reduce the cost.

Claims

1. A harmonic-characteristics based current pattern matching method performed with a monitor device for the non-intrusive power load monitoring, comprising steps: (a) establishing a load signature database of household appliances, said database comprising information about (i) power states and operating states which each appliance of said various appliances has, and (ii) steady-state current harmonic parameters of each of said operating states of each said appliance; (b) registering all electrical appliances inside a total household load and initializing a linear load state word space table in an on-board memory module of said monitor device by (i) acquiring load characteristic information for each of said electrical appliances from said load signature database and (ii) performing statistical analysis on all possible operating states of said total household load and storing results of said statistical analysis in said memory module in the form of a linear state word table; (c) performing data acquisition and data preprocessing by measuring terminal voltage and steady-state total current of said household load, which are then processed in a processing module in said monitor device to obtain a measured total fundamental active power value, a total fundamental reactive power value and a unit total current pattern; (d) performing a looking-up search on said linear state word table to obtain a feasible state word space based on said measured total fundamental active power value and said total fundamental reactive power value; (e) performing an optimal matching of current pattern based on the following equation: $\begin{array}{cc}\underset{{\mathrm{SW}}_k{}_{\mathrm{sw}}\left(P_l^1\left(t\right),Q_l^1\left(t\right)\right)}{\min }{.Math.I_l\left(P_l^1\left(t\right),Q_l^1\left(t\right)\right)-{\hat{I}}_l\left({\mathrm{SW}}_k,U_1\right).Math.}^2& \end{array}$ to obtain conresponding SW.sub.min(t) and P.sup.1.sub.min(t) values in said feasible state word space and, by disaggregating said total fundamental active power value based on said SW.sub.min(t) and P.sup.1.sub.min(t) values, to obtain the information of the power state and operating state for each of said electrical appliances inside said household load at the given point of time when terminal voltage and steady-state total current of said household load are measured; and (f) displaying said information of the power state and operating state on a screen of said monitor device; wherein in step (a) said steady-state current harmonic parameters in step (a) is determined based on the following equation: $\begin{array}{cc}{H}_{\mathrm{ai}}=\left[\begin{array}{ccccc}1{}_{1,1}& \mathrm{.Math.}& 1{}_{1,s\left(i\right)}& \mathrm{.Math.}& 1{}_{1,\mathrm{Si}}\\ \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}\\ {}_{h,1}{}_{h,1}& \mathrm{.Math.}& {}_{h,s\left(i\right)}{}_{h,s\left(i\right)}& \mathrm{.Math.}& {}_{h,\mathrm{Si}}{}_{h,\mathrm{Si}}\\ \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}\\ {}_{H,1}{}_{H,1}& \mathrm{.Math.}& {}_{H,s\left(i\right)}{}_{H,s\left(i\right)}& \mathrm{.Math.}& {}_{H,\mathrm{Si}}{}_{H,\mathrm{Si}}\end{array}\right]& \end{array}$ where ai is appliances, Si is operating states of each appliance, H is the maximum harmonic order, h is harmonic order, .sub.h,s(i) or per unit value of h-th harmonic amplitude of steady-state current under state s(i) of applicance ai with it fundamental amplitde as base value, .sub.h,s(i) is initial phase angle of h-th harmonic of steady-state current under state s(i) of appliance ai relative to fundamental phase angle of appliance terminal voltage measured; wherein in step (b) said statistical analysis is performed on total load power state, which is expressed as power vectors P1(t) R.sup.N and Q1(t) R.sup.N, consisting of fundamental powers consumed by N appliances as determined by the following two equations:
P.sup.1(t)=(P.sup.1.sub.1, . . . P.sup.1.sub.i, . . . P.sup.1.sub.N).sup.T
and
Q.sup.1(t)=(Q.sup.1.sub.1, . . . Q.sup.1.sub.i, . . . Q.sup.1.sub.N).sup.T, where superscript 1 is fundamental wave, N is the number of appliances inside said total load, i is individual appliance ai; said statistical analysis is performed further on N-dimensional state word vector SW(t) Z.sup.N as expressed in equation: SW(t)=(s(1), . . . , (s)(i), . . . s(N)).sup.T, which represent all possible operating states of said total household load and stored in a linear table in an order according to a reference value of total fundamental active power corresponding to each state word vector; and wherein in step(c) said measured total fundamental active power P.sup.1.sub.i(t) equals to U.sub.1I.sub.1cos(.sub.l1), said measured total fundamental reactive power Q.sup.1.sub.i(t) equals to U.sub.1I.sub.1sin(.sub.l1), and said unit total current pattern Il(P.sup.1.sub.l(t), Q.sup.1.sub.l(t)) equals to (1.Math..sub.l1, . . . , .sub.lh.Math..sub.lh, . . . .sub.lH.Math..sub.lH).sup.T,where U1 is fundamental wave RMS-value of measured load terminal voltage u(t), I.sub.1 is fundamental wave RMS-value of measured load total current i(t), .sub.l1 is initial phase angle of fundamental wave of current i.sub.l(t) relative to fundamental phase angle of load terminal voltage, .sub.lh is per unit value of h-th harmonic amplitude of current i.sub.l(t) with its fundamental amplitude as base value, .sub.lh is initial phase angle of h-th harmonic of current i.sub.l(t) relative to fundamental phase angle of load terminal voltage.

2. The method according to claim 1, wherein in step(a) the power state and operating state of different appliances under the fundamental wave reference voltage U.sub.ref are determined according to the following rules: different appliances are measured to determine all possible steady-state electric power, and the measured electric power levels are references to the corresponding different power states, expressed as P.sub.ref; different power states correspond to different operating states; and if an appliance has the same electric power level under different physical states, these different physical states are jointly defined as one operating state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the basic schematic diagram of non-intrusive power load monitoring and disaggregation system;

(2) FIG. 2 shows the functional flow diagram of the non-intrusive power load monitoring and disaggregation system proposed by the present invention;

(3) FIG. 3 shows the schematic diagram of the embodiment of the non-intrusive power load monitoring and disaggregation system proposed by the present invention;

(4) FIG. 4 shows the measured waveform of the air conditioner heating state;

(5) FIG. 5 shows the measured waveform of the high-fire heating state of microwave oven;

(6) FIG. 6 shows the measured waveform of the washing state of washing machine;

(7) FIG. 7 shows the measured waveform of the rice-cooking state of induction cooker.

DETAILED DESCRIPTION OF THE INVENTION

(8) The present invention will be further described in detail combining with specific embodiments.

(9) The present invention adopts individual appliance as monitoring object, and the power state (i.e. electric power) and operating state (for instance, air conditioner has two operating state of cooling and heating with different power levels) of each appliance inside the total load as monitoring target, and the following two basic hypotheses are put forward:

(10) Hypothesis 1: Under normal circumstances, a deterministic relationship exists between the fundamental active power of each appliance in the preset operating state (and the corresponding fundamental reactive power) and the load terminal voltage, which can be described via active power only (refer to: H. Pihala. Non-intrusive appliance load monitoring system based on a modern kWh-meter[R]. Technical Research Center of Finland, ESPOO, 1998.);

(11) Hypothesis 2: Under the given voltage, a one-to-one corresponding relationship exists between the appliance operating state and its steady-state current harmonic-characteristics. (refer to: Li Peng, Yu Yinxin. Nonintrusive Method for On-Line Power Load Decomposition [J]. Journal of Tianjin University, 2009, 42(4):303-308.).

(12) Based on the above two hypotheses, the present invention, namely the harmonic-characteristics based current pattern matching method for the non-intrusive power load monitoring and disaggregation, is required to establish a load signature database including the two following items:

(13) The Power State and Operating State of Different Appliances Under the Fundamental Wave Reference Voltage U.sub.ref:

(14) Under the fundamental wave reference voltage U.sub.ref, different appliances are measured to determine all possible steady states with different electric power, and different levels of electric power are defined as the corresponding power states, the reference power denotes as P.sub.ref. Different power states corresponds to different operating state, and if some appliance has the same electric power level under different physical states, then these different physical states are jointly defined as one operating state; taking the microwave oven listed in the table 1 as the example, the microwave oven has three different physical states of high-fire heating, medium-fire heating and low-fire heating, but these three operating states have the same power level, the only difference lies in the on/off duty-cycle while heating, so the microwave oven just takes the high-fire heating state as the operating state.

(15) The Steady-State Current Harmonic Parameters of Each Operating State of Different Appliances:

(16) The steady-state current harmonic parameters are obtained via harmonic analysis of the measured terminal voltages and steady-state currents of different appliances; shown in equation (4), the matrix H.sub.ai of current harmonic parameters of appliance ai is

(17) $\begin{array}{cc}{H}_{\mathrm{ai}}=\left[\begin{array}{ccccc}1{}_{1,1}& \mathrm{.Math.}& 1{}_{1,s\left(i\right)}& \mathrm{.Math.}& 1{}_{1,\mathrm{Si}}\\ \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}\\ {}_{h,1}{}_{h,1}& \mathrm{.Math.}& {}_{h,s\left(i\right)}{}_{h,s\left(i\right)}& \mathrm{.Math.}& {}_{h,\mathrm{Si}}{}_{h,\mathrm{Si}}\\ \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}\\ {}_{H,1}{}_{H,1}& \mathrm{.Math.}& {}_{H,s\left(i\right)}{}_{H,s\left(i\right)}& \mathrm{.Math.}& {}_{H,\mathrm{Si}}{}_{H,\mathrm{Si}}\end{array}\right]& \left(4\right)\end{array}$

(18) In equation (4), assuming the appliance ai having Si operating states except for the off-state, then the matrix H.sub.ai has SiZ columns, wherein s(i){1, 2, . . . , Si}; H represents the maximum harmonic order of H.sub.ai, h represents harmonic order, wherein h{1, 2, . . . , H}; .sub.h,s(i) represents the per unit value of the h-th harmonic amplitude of the steady-state current under the state s(i) of appliance ai with its fundamental amplitude as base value, so .sub.1,s(i)=1; .sub.h,s(i) represents the initial phase angle of the h-th harmonic of the steady-state current under state s(i) of appliance ai relative to the fundamental phase angle of appliance terminal voltage measured.

(19) The present invention, namely the harmonic-characteristics based current pattern matching method for the non-intrusive power load monitoring and disaggregation, comprises the following steps, and FIG. 2 shows the functional flow diagram of the non-intrusive power load monitoring and disaggregation system of the present invention:

(20) I. Step of Electrical Appliance Registration and Initialization of Load State Word Space:

(21) 1) determining the appliances inside the total load, and acquiring the load characteristic information of each appliance from the load signature database, the information includes: (1) the power state and operating state of each appliance under its fundamental wave reference voltage U.sub.ref, (2) the steady-state current harmonic parameters of each operating state of each appliance inside the total load, and thus achieving the electrical appliance registration.

(22) If the total load comprises the electrical appliances of washing machine, air conditioner, microwave oven, and induction cooker, then the information on the power state and operating state of each appliance can be obtained after finishing electrical appliance registration. The following table 1 is showing the load characteristic information of the appliances.

(23) TABLE-US-00001 TABLE I Statistical table of the load characteristic information (U.sub.ref = 220 V) Air Power (W)/ Washing conditioner/ Microwave Induction Power State machine/X K oven/W cooker/D Off-State 0 0 0 0 0 Power State 1 260/ 510/ 1374/ 1023/ washing cooling high-fire rice cooking Power State 2 200/ 800/ NULL 1479/ dehydration heating hot-pot cooking Power State 3 NULL NULL NULL 1880/ water boiling Active power 1.2 1.2 1.5 2 correction index
Remark: The three different states of high-fire heating, medium-fire heating and low-fire heating of microwave oven have same electric power, only different in power on-off duty ratio, so only the high-fire heating state of microwave oven is provided in the table.

(24) 2) Statistically analyzing all possible operating states (i.e. the combination of operating states of all appliances inside the total load) of the total load, and storing the results in the orderly linear table of [state] in the form of state word, and consequently the task of initialization of load state word space .sub.SW, can be finished.

(25) In the present invention, the total load power state is expressed as the power vector consisting of fundamental powers consumed by N appliances, as shown in equation (1) and (2), the power vectors are active power vector P.sup.1(t)R.sup.N and reactive power vector Q.sup.1(t)R.sup.N (R represents real number space) respectively, the elements thereof are respectively the fundamental active power or reactive power of N appliances in the respective power states at time t. For the given total load (i.e. the combination of the power states of N appliances), there is a one-to-one corresponding relationship between P.sup.1(t) and Q.sup.1(t), therefore the total load power state can be represented by active power vector P.sup.1 (t) only.
P.sup.1(t)=(P.sub.1.sup.1, . . . P.sub.i.sup.1, . . . ,P.sub.N.sup.1).sup.T(1)
Q.sup.1(t)=(Q.sub.1.sup.1, . . . Q.sub.i.sup.1, . . . ,Q.sub.N.sup.1).sup.T(2)

(26) In equation (1) and (2), superscript 1 represents fundamental wave, the same hereinafter, N represents the number of appliances inside the total load, i represents appliance ai, i{1, 2, . . . , N}.

(27) Furthermore, if s(i)Z (Z represents integer number space) represents the s(i)-th operating state of appliance ai, and since each appliance can only be in one operating state at time t, thus the total load operating state at time t can be represented by a N-dimensional state word vector SW(t)Z.sup.N, the elements thereof respectively represent the operating states of N appliances, as shown in equation (3):
SW(t)=(s(1), . . . ,s(i), . . . ,s(N)).sup.T(3)

(28) In equation (3): if appliance ai is in off-state, then s(i)=0.

(29) As mentioned above, the P.sup.1(t) (or Q.sup.1(t)) corresponds to one total load operating state SW(t) exclusively, and vice versa. If the load characteristic information as listed in table 1 is provided, then vector P.sup.1(t)=(260,0,1374,1479).sup.T can be written out, and SW(t)=(1,0,1,2).sup.T accordingly, which represents (at time t) the washing machine is in washing-state, air conditioner is in off-state, microwave oven is in high-fire heating state, and induction cooker is in hot-pot cooking state; if providing SW(t)=(0,1,0,3).sup.T firstly, and U.sub.ref=220V, then P.sup.1(t)=(0,510,0,1880).sup.T accordingly, and summing all the elements of P.sup.1(t) to obtain the reference value of total fundamental active power is 2390 W. Since the total load operating state can be defined by SW(t) exclusively, in order to save the storage space, state word vectors which represent all the possible operating states of the total load correspondingly are saved in the orderly linear table [state] sequentially in the ascending order according to the reference values of total fundamental active power corresponding to each state word vector, and consequentially the state word space .sub.SWZ.sup.N is formed, i.e. state space for short, wherein, Z represents integer number space.

(30) II. Step of Data Acquisition and Data Preprocessing:

(31) This step includes sampling the load terminal voltage and steady-state total current, and denoising and harmonic analysis of the measured voltage and total current signal, thereby the following results are obtained:

(32) The measured total fundamental active power P.sub.l.sup.1(t) is of:
P.sub.l.sup.1(t)=U.sub.1I.sub.1 cos(.sub.l1)(6)

(33) The measured total fundamental reactive power Q.sub.l.sup.1(t) is of:
Q.sub.l.sup.1(t)=U.sub.1I.sub.1 sin(.sub.l1)(7)

(34) The measured unit total current pattern I.sub.l(P.sub.l.sup.1(t),Q.sub.l.sup.1(t)) is of:
I.sub.l(P.sub.l.sup.1(t),Q.sub.l.sup.1(t))=(1.Math..sub.l1, . . . ,.sub.lh.Math..sub.lh, . . . ,.sub.lH.Math..sub.lH).sup.T(15)

(35) In equation (6) and equation (7): U.sub.1 represents the fundamental wave RMS-value of the measured load terminal voltage u(t), I1 represents the fundamental wave RMS-value of the measured load total current i.sub.l(t); .sub.l1 represents the initial phase angle of the fundamental wave of current i.sub.l(t) relative to the fundamental phase angle of load terminal voltage;

(36) In equation (15), .sub.lh represents per unit value of the h-th harmonic amplitude of current i.sub.l(t) with its fundamental amplitude as base value, so .sub.l1=1; .sub.lh, represents the initial phase angle of the h-th harmonic of current i.sub.l(t) relative to the fundamental phase angle of load terminal voltage.

(37) III. Step of Feasible State Word Space Search Based on Table Looking-Up:

(38) By searching the orderly linear table [state], initial selection of the total load operating state are carried out in the state word space .sub.SW based on the measured total fundamental active power P.sub.l.sup.1(t) and the measured total fundamental reactive power Q.sub.l.sup.1(t), and consequently the feasible state word space .sub.SW(P.sub.l.sup.1(t),Q.sub.l.sup.1(t))Z.sup.N meeting the fundamental total power constraints is obtained, wherein, Z represents integer number space.

(39) 1) Under the measured fundamental terminal voltage U.sub.1, the method for computing the estimation vector consisting of the fundamental active power and reactive power of each appliance, which is necessary for the initial selection of the total load operating state:

(40) Due to the voltage fluctuation of power grid, the actual operating voltage of appliance may be not U.sub.ref; according to the measured fundamental voltage U.sub.1 of the load, the reference value of active power (stored in the load signature database) under U.sub.ref is revised to obtain the estimation of actual active power of each appliance, as shown in equation (8):
P(U.sub.1)=P.sub.ref.Math.(U.sub.1/U.sub.ref).sup..sup.P(8)

(41) In equation (8), .sub.P represents the fundamental active power correction index of appliances, which can be obtained via statistical analysis of the measured data, P(U.sub.1) represents estimation of actual active power of appliance under the measured fundamental terminal voltage U.sub.1.

(42) Under the measured fundamental terminal voltage U.sub.1, the estimation vector of fundamental active power can be calculated according to the state word SW.sub.k, denoted as P.sup.1(SW.sub.k,U.sub.1) R.sup.N. According to the table 1 and equation (7), assuming SW.sub.k=(1,1,0,2).sup.T,U.sub.1=221.5V, then P.sup.1(SW.sub.k,U.sub.1)=(262.1,514.2,0,1499).sup.T, (the value of .sub.P for each appliance is shown in table 1).

(43) Furthermore, randomly selecting the k-th state word vector SW.sub.k from the orderly linear table [state], where k represents the serial number of the state word SW.sub.k in the table [state](the same hereinafter). According to the equation (3), the operating state of appliance ai in the vector SW.sub.k is s(i), and then the matrix of current harmonic parameters H.sub.a(SW.sub.k) exclusively corresponding to the vector SW.sub.k can be obtained, as shown in equation (5):

(44) $\begin{array}{cc}{H}_a\left({\mathrm{SW}}_k\right)=\left[\begin{array}{ccccc}1{}_{1,s\left(1\right)}& \mathrm{.Math.}& 1{}_{1,s\left(i\right)}& \mathrm{.Math.}& 1{}_{1,s\left(N\right)}\\ \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}\\ {}_{h,s\left(1\right)}{}_{h,s\left(1\right)}& \mathrm{.Math.}& {}_{h,s\left(i\right)}{}_{h,s\left(i\right)}& \mathrm{.Math.}& {}_{h.s\left(N\right)}{}_{h,s\left(N\right)}\\ \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}\\ {}_{H,s\left(1\right)}{}_{H,s\left(1\right)}& \mathrm{.Math.}& {}_{H,s\left(i\right)}{}_{H,s\left(i\right)}& \mathrm{.Math.}& {}_{H,s\left(N\right)}{}_{H,s\left(N\right)}\end{array}\right]& \left(5\right)\end{array}$

(45) In equation (5), H.sub.a(SW.sub.k) has N columns. Assuming the operating state s(i) of appliance ai in state word vector SW.sub.k isn't equal to zero, then the i-th column of the matrix H.sub.a(SW.sub.k) is derived from the s(i)-th column of the matrix H.sub.ai; If s(i)=0, the i-th column of the matrix H.sub.a(SW.sub.k) is zero vector.

(46) Utilizing the phase angle parameters of fundamental wave of each appliance in H.sub.a(SW.sub.k), the estimation vector of fundamental reactive power Q.sup.1(SW.sub.k,U.sub.1)R.sup.N corresponding to P.sup.1(SW.sub.k,U.sub.1)R.sup.N can be calculated according to the equation (9):
Q.sub.s(i).sup.U.sup.1=P.sub.s(i).sup.U.sup.1.Math.tan .sub.1,s(i)(9)

(47) In equation (9), .sub.1,s(i) is taken from the parameter matrix H.sub.a(SW.sub.k), P.sub.s(i).sup.U.sup.1 and Q.sub.s(i).sup.U.sup.1 are respectively the i-th element of P.sup.1(SW.sub.k,U.sub.1) and Q.sup.1(SW.sub.k,U.sub.1), i.e., the estimation of fundamental active power and reactive power of appliance ai in the state s(i) under the measured fundamental terminal voltage U.sub.1.

(48) 2) Establishing the constraints for initial selection of the total load operating state:

(49) The elements of P.sup.1(SW.sub.k,U.sub.1) and Q.sup.1(SW.sub.k,U.sub.1) respectively are summed to obtain the estimation of total load fundamental active power and reactive power, which denote as P.sub..sup.1(SW.sub.k,U.sub.1) and Q.sub..sup.1(SW.sub.k,U.sub.1); and the constraints for initial selection of the total load operating state are established, as shown in equation (10) and (11):
|P.sub..sup.1(SW.sub.k,U.sub.1)P.sub.l.sup.1(t)|.sub.P.Math.P.sub.l.sup.1(t)(10)
|Q.sub..sup.1(SW.sub.k,U.sub.1)Q.sub.l.sup.1(t)|.sub.Q.Math.Q.sub.l.sup.1(t)(11)

(50) In equation (10) and (11), .sub.P and .sub.Q respectively represent the threshold coefficient for active power and reactive power, which are respectively predetermined as 10% and 15%.

(51) In order to improve the table looking-up efficiency, the present invention takes advantages of binary looking-up algorithm to search the orderly linear table [state] according to the mentioned constraints, and consequently obtaining the feasible state word space .sub.SW(P.sub.l.sup.1 (t),Q.sub.l.sup.1(t))Z.sup.N.

(52) IV. Step of the Optimal Matching of Current Pattern:

(53) In the feasible state word space .sub.SW(P.sub.l.sup.1 (t),Q.sub.l.sup.1(t))Z.sup.N obtained in step III, which meets the constraints of the measured fundamental total active and reactive power, searching the state word SW.sub.min(t) corresponding to the estimated total current pattern that is closest to the measured current pattern (i.e. current harmonic-characteristics) by the matching method, and consequently taking the SW.sub.min(t) as the optimal estimation of the current operating state of the total load, and the P.sub.min.sup.1(t) exclusively corresponding to the SW.sub.min(t) as the optimal estimation vector of the current fundamental total active power to reflect the operating states of appliances in the total load, and finally achieving the disaggregation of fundamental total active power.

(54) The present invention also proposes a current pattern matching method as follows:

(55) 1) Under the Measured Fundamental Terminal Voltage U.sub.1, the Vector Showing the Ratio of the Fundamental Active Power Estimation of Each Appliance to that of the Total Load is as Follows:

(56) Obtaining the active power estimation vector P.sup.1(SW.sub.k,U.sub.1) according to the corresponding state word vector SW.sub.k of .sub.SW(P.sub.l.sup.1(t),Q.sub.l.sup.1(t)) and the vector showing the ratio of the fundamental active power estimation of each appliance to that of the total load according to the following equation:
.sub.P1.sup.1(SW.sub.k,U.sub.1)=(.sub.P1,k.sup.1,U.sup.1, . . . ,.sub.Pi,k.sup.1,U.sup.1, . . . ,.sub.PN,k.sup.1,U.sup.1).sup.TR.sup.N(12)

(57) In equation (12), under the measured fundamental terminal voltage U.sub.1, .sub.Pi,k.sup.1,U.sup.1=P.sub.s(i).sup.U.sup.1)/.sub.i=1.sup.NP.sub.s(i).sup.U.sup.1=P.sub.s(i).sup.U.sup.1/P.sub..sup.1(SW.sub.k,U.sub.1) represents fundamental active power ratio of appliance ai in the active power estimation vector P.sup.1(SW.sub.k,U.sub.1) corresponding to the k-th state word vector SW.sub.k in the table [state], wherein k represents the serial number of the state word vector SW.sub.k in the orderly linear table [state]. For example, if SW.sub.k=(1,1,0,2).sup.T, then .sub.P1.sup.1(SW.sub.k,U.sub.1)=(0.11,0.23,0,0.66).sup.T (U.sub.1=221.5V).

(58) 2) Under the Measured Fundamental Terminal Voltage U.sub.1, the Estimation Vector Describing the Proportion of the Current of Each Appliance in that of the Total Load is as Follows:

(59) According to equation (13), calculating the current weight coefficient .sub.i,k.sup.U.sup.1, of each appliance via the fundamental phase angle parameters in the matrix of current harmonic parameters H.sub.a(SW.sub.k) and the vector of fundamental active power ratio .sub.P1.sup.1(SW.sub.k,U.sub.1) as:

(60) $\begin{array}{cc}{}_{i,k}^{U_1}=\frac{{}_{\mathrm{Pi},k}^{1,U_1}}{\sqrt{{\left(\underset{j=1}{\overset{N}{.Math.}}{}_{\mathrm{Pj},k}^{1,U_1}\right)}^2+{\left(\underset{j=1}{\overset{N}{.Math.}}{}_{\mathrm{Pj},k}^{1,U_1}.Math.\tan {}_{1,s\left(j\right)}\right)}^2}.Math.\cos {}_{1,s\left(i\right)}}& \left(13\right)\end{array}$

(61) In equation (13), the subscript k represents the serial number of the state word vector SW.sub.k in the table [state], the subscript i represents appliance ai, according to equation (3), the subscript s(i) and s(j) represent the operating state of appliance ai and aj in state word vector SW.sub.k. The .sub.1s(i) is phase angle of the element of the i-th column in the first row of H.sub.a(SW.sub.k). And the term (SW.sub.k,U.sub.1)=(.sub.1,k.sup.U.sup.1, . . . , .sub.i,k.sup.U.sup.1, . . . , .sub.N,k.sup.U.sup.1).sup.TR.sup.N is taken as the estimation vector of the current weight coefficients.

(62) 3) Estimated Current Pattern and the Objective Function of the Current Pattern Matching:

(63) Utilizing the fundamental principle that any steady-state total load current can be approximately estimated by a linear superposition of the steady-state currents of N major electrical appliances inside the load (Refer to: Li Peng, Yu Yinxin. Nonintrusive Method for On-Line Power Load Decomposition[J]. Journal of Tianjin University, 2009, 42(4):303-308.), the vector of estimated unit total current harmonic parameters .sub.l(SW.sub.k,U.sub.1) can be calculated via the equation (14), which is called estimated total current pattern in the present invention.
.sub.l(SW.sub.k,U.sub.1)=(H.sub.a(SW.sub.k)).Math.((SW.sub.k,U.sub.1))(14)

(64) If the measured unit total current pattern corresponding to the load total fundamental power is denoted as I.sub.l(P.sub.l.sup.1(t),Q.sub.l.sup.1(t)) at time t, as shown in equation (15), the objective function of the current pattern matching in the present invention is shown in equation (16):
I.sub.l(P.sub.l.sup.1(t),Q.sub.l.sup.1(t))=(1.Math..sub.l1, . . . ,.sub.lh.Math..sub.lh, . . . ,.sub.lH.Math..sub.lH).sup.T(15)

(65) In equation (15), .sub.lh represents per unit value of the h-th harmonic amplitude of current i.sub.l(t) with its fundamental amplitude as base value, so .sub.l1=1; .sub.lh represents the initial phase angle of the h-th harmonic of current i.sub.l(t) relative to the fundamental phase angle of load terminal voltage.

(66) $\begin{array}{cc}\underset{{\mathrm{SW}}_k{}_{\mathrm{sw}}\left(P_l^1\left(t\right),Q_l^1\left(t\right)\right)}{\min }{.Math.I_l\left(P_l^1\left(t\right),Q_l^1\left(t\right)\right)-{\hat{I}}_l\left({\mathrm{SW}}_k,U_1\right).Math.}^2& \left(16\right)\end{array}$

(67) In equation (16), represents the L.sub.2 norm.

(68) 4) Disaggregation of Fundamental Wave Load According to the Current Matching Results:

(69) In the feasible state word space .sub.SW(P.sub.l.sup.1(t),Q.sub.l.sup.1(t))Z.sup.N mentioned above, the state word vector SW.sub.min(t) bringing the equation (16) to obtain the minimum value is searched and taken as the optimal estimation of the current operating state of the total load, and accordingly the appliance operating state identification is realized; and the P.sub.min.sup.1(t) exclusively corresponding to the SW.sub.min(t) is achieved as the optimal estimation of the current power state of the total load, and finally the disaggregation of total fundamental active power is realized. Combining the equation (9), the fundamental reactive power estimation of the appliances inside the total load can be calculated, and then the disaggregation of total fundamental reactive power is completed.

(70) V. Step of Display and Output of the Monitoring and Disaggregation Results:

(71) Finally, the power state (i.e. electric power) and operating state of every appliance inside the total load are output and displayed.

(72) Embodiments

(73) Based on the worldwide achievement in this field, the present invention provides an economic and practical solution of residential electricity consumption (details) monitoring method based on solving the existing technical problems.

(74) According to the FIGS. 1 and 2, an embodiment system is established shown as FIG. 3, in which a row socket is used to simulate the house distribution circuits, and the electrical appliances to be tested are connected to the socket. For the convenience of implementation, a current clamp is clamped on power line of row socket to sample the total load current. Both voltage sensor used for acquiring the load terminal voltage and isolating protective circuits are embedded in signal conditioning box. The obtained voltage and total current are transmitted to a computer for further processing via a data acquisition card, the data acquisition card links the computer storing monitoring system program and the load signature database via PCI bus. Wherein, the data acquisition card is the DAQCard-6024E data acquisition card of NI company, the computer is a laptop with basic frequency of 1.60 GHz.

(75) The partial load characteristic information of the appliances is listed in table 1, the measured voltage-current waveforms are illustrated in FIG. 4 to FIG. 7. The value of .sub.P and .sub.Q are respectively predetermined as 10% and 15%, and only the previous 11 harmonics of appliance current are considered.

(76) As shown in FIG. 2, the specific implementation for the method of the present invention mainly includes the following five steps, which are: electrical appliance registration and initialization of load state word space .sub.SW, data acquisition and data preprocessing, feasible state word space search based on table looking-up, the optimal matching of current pattern (i.e. current harmonic-characteristics) and display and output of the monitoring and disaggregation results. As shown in FIG. 2, off-line statistical analysis of the measured load data can be used to supplement and update the content of the load signature database.

(77) Electrical appliance registration and initialization of load state word space: as mentioned before, in order to implement the non-intrusive power load monitoring method of the present invention, electrical appliance registration is required after establishing the load signature database, that is to say, the composition of the electrical appliances inside the house is determined and the required load characteristic information for the implementing the monitoring method is obtained. For facilitating the customers and guaranteeing the practicability of the non-intrusive monitoring scheme, decreasing the participation of customers and reducing the complexity of the necessary operation (appliance registration for example) are needed. On the basis of electrical appliance registration, the orderly linear table [state] can be obtained once the initialization of load state word space is finished, which can be consolidated in the storage module of the monitoring system.

(78) Data acquisition and data preprocessing: the acquisition of the customer load terminal voltage and electricity total current and data preprocessing are the basis of implementing the non-intrusive power load monitoring, which have a direct effect on the performance of the monitoring method. Wherein, data preprocessing comprises denoising and harmonic analysis of the measured voltage and total current signal, which provides the measured total fundamental active power P.sub.l.sup.1(t), total fundamental reactive power Q.sub.l.sup.1(t) (see the equation (6) and equation (7)) and unit total current pattern I.sub.l(P.sub.l.sup.1(t),Q.sub.l.sup.1(t)) (see the equation (15)).

(79) Feasible state word space search based on table looking-up: searching the orderly linear table [state] to complete the initial selection of the total load operating state, and consequently obtaining the feasible state word space .sub.SW(P.sub.l.sup.1(t),Q.sub.l.sup.1(t))Z.sup.N meeting the fundamental total power constraints.

(80) The optimal matching of current pattern: in the feasible state word space .sub.SW(P.sub.l.sup.1(t),Q.sub.l.sup.1(t))Z.sup.N meeting the constraints of the measured fundamental total active and reactive power obtained from the last step, the state word SW.sub.min(t) corresponding to the estimated total current pattern that is closest to the measured current pattern (current harmonic-characteristics) is search by the matching method, which serves as the optimal estimation of the current operating state of the total load, and the P.sub.min.sup.1(t) exclusively corresponding to the SW.sub.min(t) serves as the optimal estimation vector of the current total fundamental active power, so far the disaggregation of total fundamental active power is completed; further combining the equation (9), the fundamental reactive power estimation of the appliances inside the total load can be calculated, and then the disaggregation of total fundamental reactive power is completed.

(81) Display and output of the monitoring and disaggregation results: results of the embodiment are shown in table 2.

(82) TABLE-US-00002 TABLE 2 Example test results Appliance Actual state/ Actual Monitor Absolute Relative (sign) Monitored state power result error error 1 Washing machine/X 0/0 0 0 0 NaN Microwave oven/W 1/1 1346 W 1292 W 54 W 4.01% 180 var 175 var 5 var 2.78% Air condition/K 1/1 489 W 469 W 20 W 4.09% 189 var 182 var 7 var 3.70% Induction cooker/D 0/0 0 0 0 NaN 2 Washing machine/X 1/1 244 W 238 W 6 W 2.46% 57 var 55 var 2 var 3.51% Microwave oven/W 0/0 0 0 0 NaN Air condition/K 2/2 799 W 781 W 18 W 2.25% 207 var 200 var 7 var 3.38% Induction cooker/D 1/1 901 W 880 W 21 W 2.33% 76 var 77 var 1 var 1.32% 3 Washing machine/X 1/1 231 W 222 W 9 W 3.90% 50 var 51 var 1 var 2.00% Microwave oven/W 1/1 1171 W 1120 W 51 W 4.35% 158 var 152 var 6 var 3.80% Air condition/K 1/1 489 W 468 W 21 W 4.29% 190 var 182 var 8 var 4.21% Induction cooker/D 3/3 1695 W 1632 W 63 W 3.72% 241 var 234 var 7 var 2.90% 4 Washing machine/X 0/0 0 0 0 NaN Microwave oven/W 1/1 1206 W 1200 W 6 W 0.50% 167 var 163 var 4 var 2.40% Air condition/K 2/2 825 W 821 W 4 W 0.48% 214 var 210 var 4 var 1.87% Induction cooker/D 2/2 1323 W 1317 W 6 W 0.45% 190 var 188 var 2 var 1.05%

(83) Remark: the state word 1 of air conditioner in the table refers to the cooling state in table 1. The rest is the same.

(84) The testing results of embodiment are analyzed as follows:

(85) 1. The embodiment has verified the effectiveness of the solution of this present invention. In the embodiment, the identification accuracy rate of appliance operating state is 100%, and the absolute deviation of total power disaggregation result is below 5%, both of which meet the engineering needs.

(86) 2. Based on the measurement in actual environment, the current waveform of air conditioner heating mode is similar to that of induction cooker as shown in FIGS. 4 and 7. The second case in table 2 shows that the monitoring result is not disturbed when these two appliance are simultaneously operating, that is to say the method of this present invention is not sensitive to similarity of current waveform between appliances, and the disaggregation accuracy of total power will not decrease when the measured current waveforms of different appliances have great similarity.

(87) Since there is a power difference of 8.84% between the heating state of microwave oven and the hot-pot cooking state of induction cooker, the fourth case indicates the monitoring result still has a high-accuracy, which shows the disaggregation deviation is not affected by the similar appliance power, and not sensitive to the reasonable variation of load power, therefore the present invention can accurately distinguish the different operating states with similar load power levels.

(88) Although the present invention has been described combined with the tables and figures, it isn't restricted to concrete embodiment above. In other words, the concrete embodiment above is not restrictive but only schematic. In the enlightenment of this present invention, general technician in this field can make many other variants and further develop embedded systems without any deviation from the core aim of this invention, such as, embedding the method into local smart meters, or transmitting locally-acquired electrical signal to the remote data analysis server and developing monitoring function on the basis of this present invention. All of the above are preserved in this invention.