A conditional feedback power grid frequency modulation control method based on model reference and medium

Abstract

The present invention discloses a conditional feedback grid frequency modulation control method and medium based on model reference, which obtains the pull-type transformation of the unit load frequency setting value; uses the pre-built expected model to calculate the transfer function value of the expected model; inputs the transfer function value of the expected model into the pre-built anti-disturbance controller, and adjusts the proportional gain of the anti-disturbance controller k p and integral gain k i , obtain the transfer function value of the anti-disturbance controller; calculate the tracking controller value; calculate the setting value of the model reference PID; based on the setting value of the model reference PID, calculate the load frequency modulation system input. The present invention can achieve complete separation debugging of system tracking performance and anti-disturbance performance when the accurate model of the frequency modulation system is difficult to establish or identify.

Description

Technical Field

[0001] The invention relates to a conditional feedback power grid frequency modulation control method and medium based on model reference, belonging to the technical field of automatic control. Background Art

[0002] At present, the control of load frequency regulation of units still mainly uses proportional-integral (PI) or proportional-integral-derivative (PID) controllers as the control strategy, because the PID controller has a simple structure, strong reliability and is easy to implement on the distributed control system (DCS). However, the impact of renewable energy system access on load frequency regulation makes it difficult for traditional PID controllers to have fast tracking response and strong anti-interference ability at the same time. The main reason is that its tracking performance and anti-interference performance are contradictory during the debugging process. Therefore, it is difficult for traditional PID to respond to the disturbance caused by the access of renewable energy systems while ensuring a fast response to the automatic generation control (AGC) instructions of the power grid.

[0003] Conditional Feedback (CF) control is a control method with two degrees of freedom. Its advantage is that it can completely decouple the debugging of tracking performance and anti-disturbance performance, so that both performances can be optimized at the same time. However, the design of CF control requires an accurate mathematical model based on the controlled object. It is difficult to accurately model the load frequency regulation system and the system identification is complex and time-consuming, making it difficult to apply the traditional CF control method to the load frequency regulation of the unit. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a conditional feedback grid frequency control method based on model reference, aiming to enable the unit load frequency control system to obtain optimal tracking performance and anti-interference performance, thereby quickly responding to frequency modulation instructions while effectively overcoming the disturbance caused by the access of renewable energy systems.

[0005] To achieve the above object, the present invention provides a conditional feedback grid frequency modulation control method based on model reference, comprising:

[0006] Step 1, obtaining the pull-type transformation R(s) of the unit load frequency setting value;

[0007] Step 2, using the pre-built expectation model, calculate and obtain the transfer function value H(s) of the expectation model;

[0008] Step 3: Input the transfer function value H(s) of the expected model into the pre-built disturbance rejection controller and adjust the proportional gain k of the disturbance rejection controller. p and integral gain k i , obtain the transfer function value G of the disturbance rejection controller c (s);

[0009] Step 4: Based on the expected model transfer function value H(s) and transfer function G rm (s), calculate the tracking controller value G tr (s);

[0010] Step 5: Based on the transfer function value H(s) of the expected model and the transfer function value G of the anti-disturbance controller c (s) and the tracking controller value G tr (s), calculate the set value R of the model reference PID rm (s);

[0011] Step 6: Setpoint R based on model reference PID rm (s), and calculate the load frequency regulation system input U(s).

[0012] Preferably, step 2, using the pre-built expected model, calculates the transfer function value H(s) of the expected model, which is achieved by the following steps:

[0013] The expression of the pre-built expectation model is:

[0014]

[0015] Where H(s) represents the transfer function value of the expected model, T represents the time constant of the expected model, T = 5.84 / t sd , t sd Adjust the time for your expectations.

[0016] Preferably, in step 3, the transfer function value H(s) of the expected model is input into the pre-built disturbance rejection controller, and the proportional gain k of the disturbance rejection controller is adjusted. p and integral gain k i , obtain the transfer function value G of the disturbance rejection controller c (s), which is achieved by the following steps:

[0017] The expression of the pre-built disturbance rejection controller is:

[0018]

[0019] In the formula, G c (s) represents the transfer function value of the disturbance rejection controller, k p represents the proportional gain of the disturbance rejection controller, ki represents the integral gain of the disturbance rejection controller, and s represents the Laplace operator.

[0020] Preferably, step 4, based on the transfer function value H(s) of the expected model and the transfer function G rm (s), calculate the tracking controller value G tr (s), which is achieved by the following steps:

[0021] Transfer function G rm The expression of (s) is:

[0022]

[0023] Where, T rm is the time constant of the traditional reference model;

[0024] Calculate the tracking controller value G tr (s):

[0025]

[0026] Preferably, in step 5, based on the transfer function value H(s) of the expected model and the transfer function value G of the anti-disturbance controller c (s) and the tracking controller value G tr (s), calculate the set value R of the model reference PID rm (s), which is achieved by the following steps:

[0027] Calculate the set value R of the model reference PID rm (s):

[0028] R rm (s)=[H(s)R(s)-F(s)]G c (s)+R(s)G tr (s),

[0029] Where R(s) represents the pull-type transformation of the unit load frequency setting value, and F(s) represents the load frequency.

[0030] Preferably, step 6, the setpoint R based on the model reference PID rm (s), calculate the load frequency regulation system input U(s), which can be achieved through the following steps:

[0031] Calculate the load frequency regulation system input U(s):

[0032] U(s)=[G f (s)R rm (s)-F(s)]G d (s),

[0033]

[0034]

[0035] In the formula, G f (s) represents the transfer function value of the feedforward link, G d (s) represents the transfer function value of the PID controller in the model reference PID controller, ω mr represents the closed-loop expected bandwidth of the model reference PID, and b is the adjustable parameter of the model reference PID.

[0036] Preferably, the time constant T of the conventional reference model rm =1 / ω mr .

[0037] Preferably, in step 3, the transfer function value H(s) of the expected model is input into the pre-built disturbance rejection controller, and the proportional gain k of the disturbance rejection controller is adjusted according to the engineering tuning method. p and integral gain k i .

[0038] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the above methods when executing the program.

[0039] A computer-readable storage medium stores a computer program, which implements the steps of any of the above methods when executed by a processor.

[0040] The beneficial effects achieved by the present invention are:

[0041] The present invention designs a conditional feedback control strategy based on model reference PID for the unit load frequency regulation system. It can achieve complete separation and debugging of system tracking performance and anti-disturbance performance when the accurate model of the frequency regulation system is difficult to establish or identify, so that both performances can be optimized at the same time, thereby improving the frequency regulation system's ability to respond to AGC instructions and improving its performance in dealing with the impact brought by the access of renewable energy systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the principle block diagram of traditional conditional feedback control;

[0043] Figure 2 It is a principle block diagram of the present invention;

[0044] Figure 3 It is a comparison effect diagram of the load frequency modulation control simulation between the closed-loop system output of the model reference PID and the closed-loop system output of the reference model;

[0045] Figure 4It is a simulation effect diagram of the present invention under different expected model time constants and the same anti-disturbance controller parameters;

[0046] Figure 5 This is a simulation effect diagram of the present invention under the same expected model time constant and different anti-disturbance controller parameters.

[0047] Figure 6 This is a comparison chart of simulation effects of the load frequency modulation control method of the present invention, the model reference PID and the traditional conditional feedback. DETAILED DESCRIPTION

[0048] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the protection scope of the present invention.

[0049] The present invention is achieved through the following technical solutions:

[0050] A conditional feedback load frequency modulation control method based on model reference, characterized in that it includes the following steps:

[0051] 1) Design a model reference PID controller for the unit load frequency modulation system;

[0052] The model reference PID controller includes a feedforward link and a PID controller;

[0053] Among them, the transfer function of the feedforward link is:

[0054]

[0055] In the above formula, s represents the Laplace operator, G f (s) represents the transfer function value of the feedforward link, ω mr represents the closed-loop expected bandwidth of the model reference PID controller;

[0056] The transfer function of the PID controller is:

[0057]

[0058] In the above formula, G d (s) represents the transfer function value of PID in the model reference PID controller, b is the adjustable parameter of the model reference PID controller;

[0059] 2) Transfer function G based on the feedforward link f (s) and the transfer function G of the PID controller d (s), construct the model reference PID control law;

[0060] The model reference PID control law is:

[0061] U(s)=[Gf (s)R rm (s)-F(s)]G d (s),

[0062] In the above formula, U(s) represents the load frequency modulation system input, F(s) represents the load frequency, R rm (s) represents the pull-type transformation of the model reference PID setpoint;

[0063] 3) Select the closed-loop expected bandwidth ω of the model reference PID controller mr Adjust the value of b so that the closed-loop system output of the model reference PID controller is as close as possible to the response of the following transfer function:

[0064]

[0065] Among them, G rm (s) is the response value of the transfer function, T rm is the time constant of the model reference PID controller, and T rm =1 / ω mr , s represents the Laplace operator;

[0066] 4) Response value G based on transfer function rm (s), design conditional feedback control structure;

[0067] The conditional feedback control structure includes an anticipation model, a tracking controller and an anti-disturbance controller;

[0068] The expected model is:

[0069]

[0070] In the above formula, H(s) represents the transfer function value of the expected model, T represents the time constant of the expected model, and s represents the Laplace operator;

[0071] The time constant of the expected model is given by the expected adjustment time t sd Given, that is, T = 5.84 / t sd ;

[0072] Based on the transfer function value H(s) of the expected model, a tracking controller is constructed:

[0073]

[0074] In the above formula, G tr (s) represents the transfer function value of the tracking controller, H(s) represents the transfer function value of the expected model, G rm (s) is the response value of the transfer function, T is the time constant of the expected model, T rmis the time constant of the model reference PID controller, s represents the Laplace operator;

[0075] The anti-disturbance controller is a PI controller, and the transfer function model of the anti-disturbance controller is:

[0076]

[0077] In the above formula, G c (s) represents the transfer function value of the disturbance rejection controller, k p represents the proportional gain of the disturbance rejection controller, k i represents the integral gain of the disturbance rejection controller;

[0078] 5) Based on the transfer function model of the expectation model, tracking controller and anti-disturbance controller, the control output of the control law of conditional feedback control is calculated. The control output of the control law of conditional feedback control is the set value of the model reference PID. The set value expression of the model reference PID is:

[0079] R rm (s)=[H(s)R(s)-F(s)]G c (s)+R(s)G tr (s)

[0080] In the above formula, R rm (s) is the set value of the model reference PID, H(s) represents the transfer function value of the expected model, R(s) represents the pull-type transformation of the unit load frequency set value, F(s) represents the load frequency, G c (s) represents the transfer function value of the disturbance rejection controller, G tr (s) represents the transfer function value of the tracking controller;

[0081] 6) Adjust k in the transfer function of the disturbance rejection controller p , k i , until the preset load frequency is reached. Specifically, the proportional gain k of the anti-disturbance controller is adjusted according to the engineering tuning method. p and integral gain k i This step belongs to the prior art and will not be described in detail in this embodiment.

[0082] Figure 2 The structure diagram of the load frequency modulation control based on the conditional feedback of the model reference of the present invention, in which G g (s), G t (s) and G e (s) represent the transfer function models of the steam flow control valve, steam turbine and generator respectively, and k represents the gain coefficient of the unit derating characteristic.

[0083] The transfer function models of the steam control valve, the steam turbine and the generator are respectively as well as The unit descent characteristic gain coefficient k = 5 / 12; the specific steps are as follows:

[0084] 1) Design a model reference PID controller for the single-area unit load frequency regulation system; the model reference PID controller mainly consists of two parts: a feedforward link and a PID controller;

[0085] Adjust k p , k i The size of k is adjusted until the anti-interference performance of the load frequency modulation system meets the requirements; in this embodiment, k is adjusted p =1, k i =0.05.

[0086] According to the above steps, the conditional feedback load frequency regulation control method based on model reference can be implemented. Figure 1 Compared with the traditional conditional feedback control structure shown, the present invention designs a model reference PID so that the conditional feedback control system based on model reference can independently debug the tracking response and anti-disturbance response without the need for an accurate mathematical model of the controlled object. Therefore, compared with the traditional conditional feedback control structure, it has more prospects for application in large-scale power systems.

[0087] Figure 4 and Figure 5 In order to debug and verify the complete separation of tracking performance and anti-disturbance performance for the single-area load frequency regulation system in the embodiment. During the simulation, the change of the load frequency setting value is stepped from 0Hz to 0.1Hz at 2 seconds, and a disturbance with an amplitude of -0.5 is added at 100 seconds. The initial parameters are set as: T = 5, k p =0.1, k i =0.05,ω mr =0.2, b=0.1.

[0088] Depend on Figure 3 It can be seen that when the model reference PID parameter is ω mr When =0.2 and b=0.1, the system output can track the response of its reference model more accurately, so conditional feedback control can be designed based on its reference model.

[0089] Depend on Figure 4 It can be seen that when T decreases from 5 to 3, the system tracking response gradually becomes faster, while the anti-disturbance response does not change;

[0090] Depend on Figure 5 It can be seen that when k p , k iWhen the adjustment is made, the tracking response of the system of the present invention remains unchanged, while the anti-disturbance response gradually improves. Figure 4 , Figure 5 The simulation results in show that the conditional feedback load frequency regulation control method based on model reference can achieve complete decoupling debugging of tracking performance and anti-disturbance performance without relying on the precise mathematical model of the load frequency regulation system, thereby improving the unit's response to AGC instructions while having a strong ability to overcome external disturbances.

[0091] Figure 6 For the single-area load frequency regulation system in the embodiment, the control effect of the model reference-based conditional feedback control method (the present invention) is compared with the model reference PID and the traditional conditional feedback control. During the simulation, the change in the load frequency setting value jumps from 0Hz to 0.1Hz at 2 seconds, and a disturbance with an amplitude of -0.1 is added at 100 seconds. The expected model of the traditional conditional feedback control is Tracking controller based on the second-order approximate model of load frequency regulation system Designed for The disturbance rejection controller is designed as The parameter of the present invention is ω mr = 0.2, b = 0.1. It can be seen that the conditional feedback control method based on model reference has the same expected model and anti-disturbance controller as the traditional conditional feedback control, and has the same ω as the model reference PID. mr , b. According to Figure 6 From the simulation results, it can be seen that compared with the model reference PID, the conditional feedback control based on model reference of the present invention has faster tracking response speed and better anti-disturbance performance; compared with the traditional conditional feedback control, the conditional feedback control based on model reference of the present invention has significantly stronger anti-disturbance ability when having the same tracking response speed.

[0092] In summary, the model reference-based conditional feedback load frequency regulation control method of the present invention can completely separate the debugging of the tracking performance and the anti-disturbance performance of the unit load frequency regulation system, so that the two performances can be optimized at the same time, and it is not based on the precise mathematical model design of the controlled object, so it has a wider range of applications.

[0093] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0094] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0095] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A conditional feedback power grid frequency control method based on model reference, characterized in that: include: Step 1, obtaining the pull-type transformation R(s) of the unit load frequency setting value; Step 2, using the pre-built expectation model, calculate and obtain the transfer function value H(s) of the expectation model; Step 3: Input the transfer function value H(s) of the expected model into the pre-built disturbance rejection controller and adjust the proportional gain k of the disturbance rejection controller. p and integral gain k i , obtain the transfer function value G of the disturbance rejection controller c (s); Step 4: Based on the expected model transfer function value H(s) and transfer function G rm (s), calculate the tracking controller value G tr (s); Step 5: Based on the transfer function value H(s) of the expected model and the transfer function value G of the anti-disturbance controller c (s) and the tracking controller value G tr (s), calculate the set value R of the model reference PID rm (s); Step 6: Setpoint R based on model reference PID rm (s), calculate and obtain the load frequency regulation system input U(s); Step 4: Based on the expected model transfer function value H(s) and transfer function G rm (s), calculate the tracking controller value G tr (s) , which is achieved by the following steps: Transfer function G rm The expression of (s) is: ， Where, T rm is the time constant of the traditional reference model, s represents the Laplace operator; Calculate the tracking controller value G tr (s): 。 2. A conditional feedback grid frequency modulation control method based on model reference according to claim 1, characterized in that: Step 2, using the pre-built expectation model, calculate the transfer function value H(s) of the expectation model, which is achieved by the following steps: The expression of the pre-built expectation model is: ， Where H(s) represents the transfer function value of the expected model, T represents the time constant of the expected model, T = 5.84 / t sd , t sd Adjust the time for your expectations.

3. A conditional feedback grid frequency modulation control method based on model reference according to claim 2, characterized in that: Step 3: Input the transfer function value H(s) of the expected model into the pre-built disturbance rejection controller and adjust the proportional gain k of the disturbance rejection controller. p and integral gain k i , obtain the transfer function value G of the disturbance rejection controller c (s), which is achieved by the following steps: The expression of the pre-built disturbance rejection controller is: ， In the formula, G c (s) represents the transfer function value of the disturbance rejection controller, k p represents the proportional gain of the disturbance rejection controller, k i represents the integral gain of the disturbance rejection controller, and s represents the Laplace operator.

4. The conditional feedback grid frequency modulation control method based on model reference according to claim 3 is characterized in that: Step 5: Based on the transfer function value H(s) of the expected model and the transfer function value G of the anti-disturbance controller c (s) and the tracking controller value G tr (s), calculate the set value R of the model reference PID rm (s), which is achieved by the following steps: Calculate the set value R of the model reference PID rm (s): ， Where R(s) represents the pull-type transformation of the unit load frequency setting value, and F(s) represents the load frequency.

5. A conditional feedback grid frequency modulation control method based on model reference according to claim 4, characterized in that: Step 6: Setpoint R based on model reference PID rm (s), calculate the load frequency regulation system input U(s), which can be achieved through the following steps: Calculate the load frequency regulation system input U(s): ， ， ， In the formula, G f (s) represents the transfer function value of the feedforward link, G d (s) represents the transfer function value of the PID controller in the model reference PID controller, ω mr represents the closed-loop expected bandwidth of the model reference PID, and b is the adjustable parameter of the model reference PID.

6. The conditional feedback grid frequency modulation control method based on model reference according to claim 1, characterized in that: The time constant T of the traditional reference model rm = 1 / ω mr ,ω mr Indicates the closed-loop expected bandwidth of the model reference PID.

7. The conditional feedback grid frequency modulation control method based on model reference according to claim 1, characterized in that: In step 3, the transfer function value H(s) of the expected model is input into the pre-built disturbance rejection controller, and the proportional gain k of the disturbance rejection controller is adjusted according to the engineering tuning method. p and integral gain k i .

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the method according to any one of claims 1 to 7 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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