Optical storage cooperative frequency control method, device and equipment based on model predictive control

Abstract

The invention relates to a light-storage cooperative frequency control method, device and equipment based on model predictive control, and belongs to the technical field of photovoltaic frequency control. An MPC algorithm is generated based on dynamic matrix control, and the photovoltaic output condition is determined according to the MPC algorithm; establishing a primary frequency modulation control signal selection rule for the optical storage cooperative frequency system; setting a constraint index for the primary frequency modulation control signal; establishing a dynamic equation of the optical storage grid-connected system in a discrete form based on an MPC algorithm, and determining an optimization objective function according to the dynamic equation; and a parameterized optimization result is obtained by dynamically adjusting and optimizing the objective function, and a delay compensation mechanism of delay and packet loss is formed. The robustness of frequency modulation of the optical storage system to communication delay can be improved, indexes such as overshoot and adjustment time of the system can be improved, and then the adverse effect of system performance reduction caused by delay on system operation is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic frequency control, and in particular to a photovoltaic-storage coordinated frequency control method, device and equipment based on model predictive control. Background Art

[0002] At present, the transformation of energy structure has promoted the rapid development of photovoltaic and energy storage frequency modulation systems at home and abroad. The power system is transitioning from the traditional centralized power generation mode to an intelligent distributed network composed of renewable energy and energy storage systems. In the field of photovoltaic and energy storage system frequency modulation, control strategy is a highly valued theoretical and practical engineering problem. Reasonable control strategy can better play the frequency modulation efficiency of photovoltaic and energy storage systems, and can also effectively reduce the capacity configuration of energy storage systems.

[0003] Most of the existing frequency control methods for PV-storage systems assume that the communication system can achieve real-time control of large-scale distributed loads, without considering the impact of communication delays in the frequency modulation process. When PV-storage systems participate in the frequency modulation of power systems, due to factors such as signal transmission and processing, there will be time delays in the information transmission channel when the telemetry signal is sent from the remote terminal unit to the control center, the control signal is transmitted from the control center to the individual unit, and the signal processing and control update. The communication delay of the channel may affect the performance of the system frequency control. Summary of the invention

[0004] In view of the above problems, the present disclosure proposes a photovoltaic-storage coordinated frequency control method, device and equipment based on model predictive control, which is beneficial to improving the robustness of the photovoltaic-storage system frequency modulation to communication delays. Indicators such as the system's overshoot and adjustment time have been significantly improved, thereby reducing the adverse effects of system performance degradation caused by delays on system operation.

[0005] The present disclosure provides a method for photovoltaic-storage coordinated frequency control based on model predictive control, including:

[0006] Generate an MPC algorithm based on dynamic matrix control, and determine the photovoltaic output according to the MPC algorithm;

[0007] For the photovoltaic-storage coordinated frequency system, a primary frequency modulation control signal selection rule is established; and a constraint index is set for the primary frequency modulation control signal;

[0008] Based on the MPC algorithm, a discrete form of dynamic equation of the photovoltaic energy storage grid-connected system is established, and an optimization objective function is determined according to the dynamic equation;

[0009] By dynamically adjusting the optimization objective function, parameterized optimization results are obtained to form a delay compensation mechanism for delay and packet loss.

[0010] Furthermore, determining the photovoltaic output according to the MPC algorithm includes:

[0011] The incremental control input of the photovoltaic storage active power is used as the step input of the MPC algorithm, and the system model is established through the probability density function; the state vector in the system model is adjusted by dynamically adjusting the incremental control input value of the photovoltaic output active power.

[0012] Furthermore, the step of using the solar energy storage active power increment control input as the step input of the MPC algorithm includes:

[0013] The light intensity and maximum light intensity of the solar energy storage system are used as the active power increment control input and as the step input of the MPC algorithm.

[0014] Furthermore, for the photovoltaic-storage coordinated frequency system, a primary frequency modulation control signal selection rule is established, including:

[0015] There are two working conditions under the step input disturbance load: fixed communication delay and time-varying communication delay;

[0016] A selection rule for the primary frequency modulation control signal is established for fixed communication delay conditions and time-varying communication delay conditions.

[0017] Furthermore, the method further comprises:

[0018] The value of the photovoltaic output variable in a certain time period is limited by a constraint link, wherein the photovoltaic output variable is limited by the photovoltaic output at a first moment and the photovoltaic output at a second moment in the certain time period.

[0019] Furthermore, setting a constraint index for the primary frequency modulation control signal includes:

[0020] Design the optimization objective function and limiting constraints of the photovoltaic energy storage grid-connected system;

[0021] These include constraints on the upper limit of the active power of energy storage units, the active output of photovoltaics, and the active output of photovoltaic and storage grid-connected systems.

[0022] Furthermore, the method further comprises:

[0023] The delay compensation mechanism is determined according to the optimization objective function of the photovoltaic-storage-grid-connected system, and the optimization objective function of the photovoltaic-storage-grid-connected system is determined according to the dynamic equation of the photovoltaic-storage-grid-connected system.

[0024] Based on the same inventive concept, the embodiment of the present disclosure further provides a photovoltaic-storage coordinated frequency control device based on model predictive control, including:

[0025] An algorithm unit, used to generate an MPC algorithm based on dynamic matrix control and determine the photovoltaic output according to the MPC algorithm;

[0026] The frequency modulation unit is used to establish a primary frequency modulation control signal selection rule for the optical-storage coordinated frequency system; and set a constraint index for the primary frequency modulation control signal;

[0027] A model unit, used for establishing a discrete form of a dynamic equation of a photovoltaic energy storage grid-connected system based on an MPC algorithm, and determining an optimization objective function according to the dynamic equation;

[0028] The optimization unit is used to obtain parameterized optimization results by dynamically adjusting the optimization objective function, thereby forming a delay compensation mechanism for delay and packet loss.

[0029] Based on the same inventive concept, another aspect of the embodiment of the present disclosure further provides an electronic device, comprising: a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0030] a memory storing a computer program;

[0031] The processor implements a photovoltaic energy storage coordinated frequency control method based on model predictive control when executing the program stored in the memory.

[0032] Based on the same inventive concept, the embodiment of the present disclosure further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, a photovoltaic-storage coordinated frequency control method based on model predictive control is implemented.

[0033] Beneficial effects of the present disclosure:

[0034] The present invention generates an MPC algorithm based on dynamic matrix control, determines the photovoltaic output according to the MPC algorithm; establishes a primary frequency modulation control signal selection rule for the photovoltaic storage coordinated frequency system; sets constraint indicators for the primary frequency modulation control signal; establishes a discrete form of photovoltaic storage grid-connected system dynamic equation based on the MPC algorithm, determines the optimization objective function according to the dynamic equation; obtains parameterized optimization results by dynamically adjusting the optimization objective function, and forms a delay compensation mechanism for delay and packet loss. It can improve the robustness of the photovoltaic storage system frequency modulation to communication delay, improve the system's overshoot and adjustment time and other indicators, and thus reduce the adverse effects of system performance degradation caused by delay on system operation.

[0035] Other features and advantages of the present disclosure will be described in the following description, and partly become apparent from the description, or be understood by implementing the present disclosure. The purpose and other advantages of the present disclosure can be realized and obtained by the structures indicated in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A flow chart of a photovoltaic-storage coordinated frequency control method based on model predictive control in the present application is shown;

[0038] Figure 2 A schematic diagram of a photovoltaic-storage coordinated frequency control device based on model predictive control in the present application is shown;

[0039] Figure 3 The flow chart of frequency modulation parameters and network delay control in the embodiment of the present application is shown;

[0040] Figure 4 A schematic diagram showing the relationship between light intensity and probability density after frequency modulation control in an embodiment of the present application is shown;

[0041] Figure 5 A schematic diagram of an electronic device in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0043] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0044] The present invention proposes a photovoltaic-storage coordinated frequency control method, device and equipment based on model predictive control, which is beneficial to improving the robustness of photovoltaic-storage system frequency modulation to communication delays. Indicators such as the system's overshoot and adjustment time have been significantly improved, thereby reducing the adverse effects of system performance degradation caused by delays on system operation.

[0045] It should be noted that the MPC algorithm, namely Model Predictive Control, is a model-based control method that predicts the state and control input for a period of time in the future, and then calculates the current optimal control input based on the prediction results. This application is based on the idea of ​​dynamic matrix control, improves the MPC algorithm of the transmission, takes the active power increment of the photovoltaic storage as the dynamic matrix parameter, and takes the active power increment control input of the photovoltaic storage as the step input, and characterizes the uncertainty of photovoltaic output through the model.

[0046] The present disclosure provides a method for controlling the frequency of photovoltaic and energy storage coordination based on model predictive control. Figure 1 ,include:

[0047] S101: Generate an MPC algorithm based on dynamic matrix control, and determine the photovoltaic output according to the MPC algorithm;

[0048] S102: establishing a primary frequency modulation control signal selection rule for the photovoltaic energy storage coordinated frequency system; and setting a constraint index for the primary frequency modulation control signal;

[0049] S103: establishing a discrete form of a dynamic equation of the photovoltaic energy storage grid-connected system based on the MPC algorithm, and determining an optimization objective function according to the dynamic equation;

[0050] S104: Obtain parameterized optimization results by dynamically adjusting the optimization objective function, thereby forming a delay compensation mechanism for delay and packet loss.

[0051] In step S101, determining the photovoltaic output according to the MPC algorithm includes:

[0052] The incremental control input of the photovoltaic storage active power is used as the step input of the MPC algorithm, and the system model is established through the probability density function; the state vector in the system model is adjusted by dynamically adjusting the incremental control input value of the photovoltaic output active power.

[0053] Specifically, the step of using the solar energy storage active power increment control input as the step input of the MPC algorithm includes:

[0054] The light intensity and maximum light intensity of the solar energy storage system are used as the active power increment control input and as the step input of the MPC algorithm.

[0055] Specifically, in step S101, the solar energy storage active power increment control input is regarded as a step input, and considering the uncertainty characteristics of photovoltaic output, a probability density function model is adopted to dynamically adjust the state vector in the system model. The dynamic adjustment model is as follows:

[0056]

[0057] Where: r is the light intensity; τ() is the Gamma function; r max is the maximum light intensity; α and β are the parameters of Beta distribution, which are obtained by fitting the actual data; f is the independent variable function; the f function is the probability density function of the illumination in the predicted period fitted according to the historical illumination data.

[0058] The least squares method is used to fit the functional relationship between the output power of the photovoltaic unit and the light intensity. According to the above probability density function model, the changes in light intensity in different time periods can be obtained, and then:

[0059] ΔP out =k·Δr+h

[0060] Where: ΔP out is the power fluctuation caused by light change; k is the slope; h is the intercept; Δr is the change in light intensity.

[0061] The photovoltaic output power value is used to make real-time corrections to the step input, as follows:

[0062]

[0063] Where: ΔP L , ΔP′ L is the load disturbance power input before and after correction; P N is the rated power; m and n are weight coefficients.

[0064] Furthermore, for the photovoltaic-storage coordinated frequency system, a primary frequency modulation control signal selection rule is established, including:

[0065] There are two working conditions under the step input disturbance load: fixed communication delay and time-varying communication delay;

[0066] A selection rule for the primary frequency modulation control signal is established for fixed communication delay conditions and time-varying communication delay conditions.

[0067] Specifically, the value of the photovoltaic output variable in a certain time period is limited by a constraint link, wherein the photovoltaic output variable is limited by the photovoltaic output at a first moment and the photovoltaic output at a second moment in the certain time period.

[0068] Specifically, in step S102, two working conditions are set under the new step disturbance load, namely, fixed communication delay and time-varying communication delay, so as to establish the selection rule of the primary frequency modulation control signal. m to s The photovoltaic output variable P at the moment pv The value is as shown below

[0069]

[0070] Among them, f ref is the rated reference value of frequency; P pv , P′ pv This is the photovoltaic output before and after the update.

[0071] In some implementations, setting a constraint indicator for the primary frequency modulation control signal includes:

[0072] Design the optimization objective function and limiting constraints of the photovoltaic energy storage grid-connected system;

[0073] These include constraints on the upper limit of the active power of energy storage units, the active output of photovoltaics, and the active output of photovoltaic and storage grid-connected systems.

[0074] Specifically, the optimization objective function and limiting constraint of the photovoltaic energy storage grid-connected system are designed, which can be expressed as:

[0075] min|Δf low |

[0076]

[0077] Where: Δf low is the frequency deviation corresponding to the lowest frequency point; P ESS is the upper limit of the active power of the energy storage unit; P pv is the active power output of photovoltaic; a is the active output of the photovoltaic energy storage system, A is the state matrix of the system; B is the input matrix of the system; u(k) is the control variable; x(k) is the state variable; k is the time variable of the discrete system.

[0078] The first constraint is the capacity limitation of the photovoltaic inverter; the second constraint is the power limitation of the energy storage unit; and the third constraint is the dynamic equation of the photovoltaic and energy storage grid-connected system in discrete form.

[0079] Furthermore, the method also includes: dynamically adjusting the multi-step control signal based on the dynamic matrix control concept to form a delay compensation mechanism that takes delay and packet loss into consideration.

[0080] The delay compensation mechanism is determined according to the optimization objective function of the photovoltaic-storage-grid-connected system, and the optimization objective function of the photovoltaic-storage-grid-connected system is determined according to the dynamic equation of the photovoltaic-storage-grid-connected system.

[0081] The present invention provides a photovoltaic-storage coordinated frequency control method based on model predictive control, which improves the robustness of the photovoltaic-storage system frequency modulation to communication delays, and significantly improves indicators such as the system's overshoot and adjustment time, thereby reducing the adverse effects of system performance degradation caused by delays on system operation.

[0082] The control concept of the disclosed control method is described below with reference to the accompanying drawings.

[0083] See also Figure 3 , the present invention uses probability density to simulate the incremental control input of photovoltaic energy storage, and regards it as a dynamic step input of the system; constructs a frequency response model of the photovoltaic energy storage system, initializes the MPC controller parameters, obtains the latest status information of the photovoltaic energy storage system at time t, and sends it to the MPC main controller; solves the optimal control matrix of the frequency modulation parameters of the photovoltaic energy storage system based on the system frequency information, and determines whether network delay occurs. When there is no network delay, the optimization is successful. When there is still a network delay, the delay type is determined and compensated, and then the MPC controller parameters are initialized to obtain the latest status information of the photovoltaic energy storage system at time t, and send it to the MPC main controller; solves the optimal control matrix of the frequency modulation parameters of the photovoltaic energy storage system based on the system frequency information, and determines whether network delay occurs; repeats the above steps until network delay does not occur. See. Figure 4 It can be seen that after the cyclic iteration of the above control algorithm, the stronger the light intensity, the smaller the probability density, which improves the robustness of the frequency modulation of the photovoltaic storage system to communication delays, and the system's overshoot and adjustment time are significantly improved, thereby reducing the adverse effects of system performance degradation caused by delays on system operation.

[0084] Based on the same inventive concept, the present disclosure also provides a photovoltaic storage coordinated frequency control device based on model predictive control, see Figure 2 ,include:

[0085] An algorithm unit 201 is used to generate an MPC algorithm based on dynamic matrix control, and determine the photovoltaic output according to the MPC algorithm;

[0086] The frequency modulation unit 202 is used to establish a primary frequency modulation control signal selection rule for the photovoltaic energy storage coordinated frequency system; and set a constraint index for the primary frequency modulation control signal;

[0087] Model unit 203, used to establish a discrete form of dynamic equation of the photovoltaic energy storage grid-connected system based on the MPC algorithm, and determine the optimization objective function according to the dynamic equation;

[0088] The optimization unit 204 is used to obtain parameterized optimization results by dynamically adjusting the optimization objective function, thereby forming a delay compensation mechanism for delay and packet loss.

[0089] Based on the same inventive concept, the present disclosure also provides an electronic device 161, see Figure 5 , including a processor 164, a communication interface 165, a memory 162 and a communication bus, wherein the processor 164, the communication interface 165 and the memory 162 communicate with each other through the communication bus;

[0090] A memory 162 storing a computer program 163;

[0091] When the processor 164 executes the program stored in the memory 162, a photovoltaic energy storage coordinated frequency control method based on model predictive control is implemented.

[0092] The above communication bus may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus may be divided into an address bus, a data bus, a control bus, etc.

[0093] The communication interface 165 is used for communication between the electronic device 161 and other devices.

[0094] The memory 162 may include a random access memory 162 (RAM), or may include a non-volatile memory 162 (non-volatile memory), such as at least one disk memory 162. Optionally, the memory 162 may also be at least one storage device located away from the processor 164.

[0095] The above-mentioned processor 164 can be a general-purpose processor 164, including a central processing unit 164 (CPU), a network processor 164 (NP), etc.; it can also be a digital signal processor 164 (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components.

[0096] Based on the same inventive concept, the embodiment of the present disclosure further provides a computer-readable storage medium storing a computer program 163 , which implements a photovoltaic-storage coordinated frequency control method based on model predictive control when executed by a processor 164 .

[0097] The computer-readable storage medium may be included in the device / apparatus described in the above embodiment; or it may exist independently without being assembled into the device / apparatus. The above computer-readable storage medium carries one or more programs. When the above one or more programs are executed, the photovoltaic energy storage coordinated frequency control method based on model predictive control according to the embodiment of the present disclosure is implemented.

[0098] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A photovoltaic energy storage coordinated frequency control method based on model predictive control, characterized in that: include: Generate an MPC algorithm based on dynamic matrix control, and determine the photovoltaic output according to the MPC algorithm; For the photovoltaic-storage coordinated frequency system, a primary frequency modulation control signal selection rule is established; and a constraint index is set for the primary frequency modulation control signal; Based on the MPC algorithm, a discrete form of dynamic equation of the photovoltaic energy storage grid-connected system is established, and an optimization objective function is determined according to the dynamic equation; By dynamically adjusting the optimization objective function, parameterized optimization results are obtained to form a delay compensation mechanism for delay and packet loss.

2. The method according to claim 1, characterized in that Determining the photovoltaic output according to the MPC algorithm includes: The incremental control input of the photovoltaic storage active power is used as the step input of the MPC algorithm, and the system model is established through the probability density function; the state vector in the system model is adjusted by dynamically adjusting the incremental control input value of the photovoltaic output active power.

3. The method according to claim 2, characterized in that The step of using the solar energy storage active power increment control input as the step input of the MPC algorithm includes: The light intensity and maximum light intensity of the solar energy storage system are used as the active power increment control input and as the step input of the MPC algorithm.

4. The method according to claim 3, characterized in that The primary frequency modulation control signal selection rule is established for the photovoltaic energy storage coordinated frequency system, including: There are two working conditions under the step input disturbance load: fixed communication delay and time-varying communication delay; A selection rule for the primary frequency modulation control signal is established for fixed communication delay conditions and time-varying communication delay conditions.

5. The method according to claim 4, characterized in that The method further comprises: The value of the photovoltaic output variable in a certain time period is limited by a constraint link, wherein the photovoltaic output variable is limited by the photovoltaic output at a first moment and the photovoltaic output at a second moment in the certain time period.

6. The method according to claim 1, characterized in that Setting a constraint index for the primary frequency modulation control signal includes: Design the optimization objective function and limiting constraints of the photovoltaic energy storage grid-connected system; These include constraints on the upper limit of the active power of energy storage units, the active output of photovoltaics, and the active output of photovoltaic and storage grid-connected systems.

7. The method according to claim 6, characterized in that The method further comprises: The delay compensation mechanism is determined according to the optimization objective function of the photovoltaic-storage-grid-connected system, and the optimization objective function of the photovoltaic-storage-grid-connected system is determined according to the dynamic equation of the photovoltaic-storage-grid-connected system.

8. A photovoltaic energy storage coordinated frequency control device based on model predictive control, characterized in that: include: An algorithm unit, used to generate an MPC algorithm based on dynamic matrix control and determine the photovoltaic output according to the MPC algorithm; A frequency modulation unit, used for establishing a primary frequency modulation control signal selection rule for the optical-storage coordinated frequency system; and setting a constraint index for the primary frequency modulation control signal; A model unit, used for establishing a discrete form of a dynamic equation of a photovoltaic energy storage grid-connected system based on an MPC algorithm, and determining an optimization objective function according to the dynamic equation; The optimization unit is used to obtain parameterized optimization results by dynamically adjusting the optimization objective function, thereby forming a delay compensation mechanism for delay and packet loss.

9. An electronic device, characterized in that: include: A processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; a memory storing a computer program; The processor, when executing the program stored in the memory, implements the photovoltaic energy storage coordinated frequency control method based on model predictive control as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, a photovoltaic-storage coordinated frequency control method based on model predictive control is implemented as described in any one of claims 1 to 7.

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