DISTRIBUTED COLLABORATIVE CONTROL METHOD FOR MICROGRID FREQUENCY UNDER ATTACK OF FALSE DATA INJECTION BASED ON CYBER-PHYSICAL FUSION

Abstract

A simulation method of distributed collaborative control for a microgrid under the attack of false data injection based on cyber-physical fusion is provided, which includes: establishing a distributed collaborative control simulation model for the microgrid frequency based on an RT_LAB real-time simulation tool OPAL-RT; designing a distributed collaborative control algorithm of a microgrid under the attack of false data injection based on DSP; simulating real-time communication among distributed generations based on an OPNET; simulating constant injection of false data, to realize that the frequency of each distributed generation in the microgrid is finally strictly tracked to the reference frequency. According to the method provided by the present application, no extra state observer is needed to observe the angular frequency states of local and neighboring nodes, so that the adverse effects caused by the attack of false data with a constant injection can be completely eliminated.

Claims

1. A stimulation method of distributed collaborative control for a microgrid frequency under attack of false data injection based on cyber-physical fusion, comprising following steps: S1, establishing a distributed collaborative control simulation model for a microgrid frequency based on a RT_LAB real-time simulation tool OPAL-RT; S2, designing a distributed collaborative control algorithm for a microgrid under the attack of false data injection based on a DSP; S3, simulating a real-time communication among distributed generations based on an OPNET; and S4, simulating constant injection of false data such that the microgrid frequency is strictly tracked to a reference frequency ultimately.

2. The stimulation method of distributed collaborative control for microgrid frequency under the attack of false data injection based on cyber-physical fusion according to claim 1, wherein the step S1 specifically comprises: establishing a simulation model of a distributed generation cluster in a RT-LAB, realizing a physical mirror image of the cluster, and using a target machine to expand a signal output port of the cluster, wherein the simulation model includes two parts, a first part is a primary circuit module composed of a distributed generation with a voltage source converter (VSC) and a three-phase AC load of the microgrid, and a second part is a secondary control module composed of a plurality of distributed generation PWM pulse control modules.

3. The stimulation method of distributed collaborative control for microgrid frequency under the attack of false data injection based on cyber-physical fusion according to claim 2, wherein the step S2 specifically comprises: acquiring analog quantity from the signal output port of the RT-LAB of the secondary control module by the DSP to realize a distributed collaborative control algorithm for the microgrid under the attack of false data injection, wherein a digital signal is uploaded to the secondary control module in the RT-LAB through a preset communication protocol.

4. The stimulation method of distributed collaborative control for microgrid frequency under the attack of false data injection based on cyber-physical fusion according to claim 2, wherein in the step S2, the distributed collaborative control algorithm for the microgrid frequency under the attack of false data injection specifically comprises: in the microgrid, accessing the distributed generations to the microgrid through the VSC to supply power to the microgrid, and controlling active power and reactive power of an output of the VSC by a traditional droop control method; $\begin{array}{cc}\{\begin{array}{c}{\omega }_i={\omega }_{n,i}-m_{p,i}{P}_i\\ U_{mag,i}=U_{n,i}-n_{q,i}{Q}_i\end{array}& \left(1\right)\end{array}$ wherein ω.sub.i and U.sub.mag,i are an angular frequency and a voltage of an output of an inverter i respectively, P.sub.i and Q.sub.i are an active power and a reactive power of the output of the inverter i respectively; m.sub.p,i and n.sub.q,i are an active droop coefficient and a reactive droop coefficient of the inverter i respectively, which are obtained by a rated value of the inverter; ω.sub.n,i and U.sub.n,i are an angular frequency and a voltage set point of the inverter i respectively; performing a secondary control to compensate for frequency and voltage deviations in a droop control; wherein the secondary control is intended to restore a frequency and a voltage to a normal working range by adjusting the angular frequency and the voltage set point; only distributed collaborative control under attack is analyzed, and a control objective is that in the case of attack, a secondary control algorithm is designed to satisfy a following formula:
lim.sub.t−∝|ω.sub.i−ω.sub.ref=0  (2) wherein ω.sub.i is an angular frequency of the i.sup.th distributed generation; ω.sub.ref is a reference angular frequency; and t denotes a control time; in order to achieve the above control objective by using distributed collaborative control, designing an auxiliary controller to obtain a control input ω.sub.n,i in Formula (2); differentiating the Formula (1) as:
{dot over (ω)}.sub.i={dot over (ω)}.sub.n,i−m.sub.p,i{dot over (P)}.sub.i=u.sub.i  (3) wherein {dot over (ω)}.sub.i, {dot over (ω)}.sub.n,i and {dot over (P)}.sub.i are differentials of ω.sub.i, ω.sub.n,i and P.sub.i; u.sub.i is a control rate of the distributed collaborative control algorithm against the attack of false data injection;
u.sub.i=−k.sub.ω∫[Σ.sub.j∈N.sub.ia.sub.i,j(ω.sub.i−ω.sub.j)+b.sub.i(ω.sub.i−ω.sub.ref)]dt−ω.sub.i  (4) wherein k.sub.ω, a.sub.i,j, b.sub.i are all control coefficients, ω.sub.i is an angular frequency of the i.sup.th distributed generation, ω.sub.j is an angular frequency of the j.sup.th distributed generation, and N.sub.i is a set of distributed generations collaborating with the distributed generation i; the design of the above control rate is capable of eliminating the influence on the secondary control when the false data injection is a constant.

5. The stimulation method of distributed collaborative control for microgrid frequency under the attack of false data injection based on cyber-physical fusion according to claim 1, wherein in the step S3, the OPNET acts as a router for simulating signal transmission and reception among distributed generation controllers (DSPs) to realize physical topology simulation and realize interaction of a frequency collaborative control signal of a distributed generation unit.

6. The stimulation method of distributed collaborative control for microgrid frequency under attack of false data injection based on cyber-physical fusion according to claim 1, wherein the step S4 specifically comprises: specifying a secondary control attack value for the microgrid frequency by a platform model, simulating the false data injection, and transmitting a frequency fluctuation value to a DSP controller by the RT-LAB simulation model; performing a distributed generation frequency secondary control algorithm in the DSP controller; transmitting the control signal back to RT-LAB simulation model, so as to realize distributed collaborative control for microgrid frequency under the attack of false data injection.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is a structural diagram of a simulation system for distributed collaborative control based on cyber-physical fusion according to the present application;

[0031] FIG. 2 is an OPNET network simulation model; and

[0032] FIG. 3 is an evaluation result for an embodiment of the present application.

DESCRIPTION OF EMBODIMENTS

[0033] The present application will be further described in detail with reference to the attached drawings and specific embodiments.

[0034] A distributed control method for microgrid frequency under attack of false data injection based on cyber-physical fusion is provided according to an embodiment, which includes the following steps.

[0035] Step 1: establishing a distributed collaborative control simulation model for a microgrid frequency based on a RT_LAB real-time simulation tool OPAL-RT.

[0036] Specifically, in this embodiment, a simulation model of a distributed generation cluster for microgrid is constructed in the RT-LAB, a physical mirror image thereof is realized, and a signal output port thereof is expanded by using a target machine. The simulation model consists of two parts. The first part includes a distributed generation simulation unit of a DC power source inverting three-phase AC in parallel connection with a primary circuit module of the microgrid. The second part includes PWM pulse secondary control systems of respective distributed generations.

[0037] In this embodiment, a circuit of the DC power source inverting three-phase AC simulates the distributed generations, and four distributed generations are connected in parallel to form the distributed generation cluster. The power control of the distributed generation is controlled by a PWM pulse of an inverter conversion control module, and the pulse signal is generated by a secondary control module.

[0038] Step 2: designing a distributed collaborative control algorithm for the microgrid under the attack of the false data injection based on a DSP.

[0039] Specifically, in the microgrid, the distributed generation is accessed to the microgrid through the VSC to supply power to the microgrid, and active power and reactive power of an output of the VSC are controlled by a traditional droop control method:

[00002]$\begin{array}{cc}\{\begin{array}{c}{\omega }_i={\omega }_{n,i}-m_{p,i}{P}_i\\ U_{mag,i}=U_{n,i}-n_{q,i}{Q}_i\end{array}.& \left(1\right)\end{array}$

[0040] In the formula (1), ω.sub.i and U.sub.mag,i are an angular frequency and a voltage of an output of an inverter i respectively, P.sub.i and Q.sub.i are an active power and a reactive power of the output of the inverter i respectively; m.sub.p,i and n.sub.q,i are active and reactive droop coefficients of the inverter i respectively, which are obtained by a rated value of the inverter; and ω.sub.n,i and U.sub.n,i are an angular frequency and a voltage set point of the inverter i respectively.

[0041] Droop control will lead to frequency and voltage deviations, so a secondary control is needed to make compensation. The secondary control is intended to restore a frequency and a voltage to a normal working range by adjusting the angular frequency and the voltage set point. Only distributed collaborative control under attack is analyzed in the present application. Thus, a control objective is that: in the case of attack, a secondary control algorithm is designed such that the following formula is satisfied:

lim.sub.t−∝|ω.sub.i−ω.sub.ref=0  (2).

[0042] In the formula (2), ω.sub.i is an angular frequency of the i.sup.th distributed generation; ω.sub.ref is a reference angular frequency; and t denotes a control time.

[0043] In order to achieve the above control objective by using distributed collaborative control, an auxiliary controller needs to be designed to obtain a control input ω.sub.n, in Formula (2). The Formula (1) is differentiated as:

{dot over (ω)}.sub..Math.={dot over (ω)}.sub.n,.Math.−m.sub.p,i{dot over (P)}.sub..Math.=u.sub.i  (3).

[0044] In the formula (3), {dot over (ω)}.sub..Math., {dot over (ω)}.sub.n,.Math. and {dot over (P)}.sub..Math. are differentials of ω.sub.i, ω.sub.n,i and P.sub.i; u.sub.i is a control rate of the distributed collaborative control algorithm against the attack of false data injection.

u.sub.i=−k.sub.ω∫[Σ.sub.j∈N.sub.ia.sub.i,j(ω.sub.i−ω.sub.j)+b.sub.i(ω.sub.i−ω.sub.ref)]dt−ω.sub.i  (4)

[0045] in the formula (4), k.sub.ω, a.sub.i,j, b.sub.i are all control coefficients, ω.sub.i is an angular frequency of the i.sup.th distributed generation, ω.sub.j is an angular frequency of the i.sup.th distributed generation, and N.sub.i is a set of distributed generations collaborating with the distributed generation i; the design of the above control rate is capable of eliminating the influence on the secondary control when the false data injection is a constant.

[0046] Furthermore, in the step S3, the OPNET acts as a router for simulating signal transmission and reception among distributed generation controllers (DSPs) to realize physical topology simulation and realize interaction of a frequency collaborative control signal of a distributed generation unit.

[0047] Step 3: simulating real-time communication among distributed generations based on OPNET.

[0048] Specifically, in this embodiment, the OPNET plays the role of a router, which is used to simulate the transmission and reception of signals among distributed generation controllers (DSPs) to realize physical topology simulation and realize the interaction of frequency signals of the distributed generations. According to the microgrid structure with distributed generations, the OPNET communication topology is designed as shown in FIG. 2. An OPNET software is used to build a communication network among distributed generations and set corresponding communication nodes, which refer to the communication nodes of actual running equipment in distributed generations. Then, the switch receives the operating state data in the DSP controller in real time, sends the data to the OPNET through the communication board card, and participates in the network communication process of the microgrid with distributed generations as an actual node. In this way, the real-time communication among distributed generations is stimulated by the OPNET. The data flow of the communication network mainly includes the actual frequency sent from each distributed generation unit to adjacent distributed generation units.

[0049] Step 4: simulating the attack of false data injection to realize distributed collaborative control for microgrid frequency under the attack of false data injection.

[0050] Specifically, in an embodiment, the attack value of the secondary control for a microgrid frequency is specified through the platform model, and false data injection is simulated. The AC frequency of each distributed generation is transmitted to the DSP controller through the RT-LAB simulation model, and calculated by the distributed generation frequency secondary control algorithm in the DSP controller. Then, the control signal is transmitted back to the RT-LAB simulation model, thus realizing distributed collaborative control for microgrid frequency under the attack of false data injection.

[0051] The solution of the present application is further verified by specific examples below.

[0052] Based on the semi-physical simulation platform of RT-LAB, the DSP controller and the OPNET network simulation software, a cyber-physical fusion simulation system is constructed as shown in FIG. 1, and the distributed collaborative control method for microgrid frequency under the attack of false data injection according to the present application is experimentally verified.

[0053] The experimental screenshot is shown in FIG. 3, which is the result of distributed collaborative control for microgrid frequency under the attack of false data injection based on cyber-physical fusion according to the embodiment.

[0054] In this embodiment, the microgrid is composed of four distributed generators and an AC load. The DC power supply is converted into a three-phase AC to simulate distributed generations, and the PWM pulse input of the converter control module is controlled by the DSP, thereby controlling the active power of distributed output. In the DC-AC inverter module, the inverter inverts 700V DC voltage into 220V AC voltage. When the system is stable, the AC bus frequencies of the four distributed generations are all 50 Hz. The simulation waveforms in FIG. 3 are change curves of the two states, i.e., the state of the frequency at the three-phase AC side of the four distributed generations from start-up to stable operation and the state of the frequency at the three-phase AC side of the four distributed generations from stable operation to false data injection. It can be seen from FIG. 3 that the distributed microgrid receives the attack of false data injection at the time of 1 s, and the control system quickly eliminates the attack, and the four distributed generations resume stable operation at 50 Hz.

[0055] The above specific embodiments are used to explain the present application, but not to limit the present application. Any modifications and changes made to the present application within the spirit of the present application and the protection scope of the claims fall into the protection scope of the present application.