Distributed photovoltaic power generation steady-state and transient-state frequency coordination control method and system

Abstract

The invention relates to the technical field of power systems, in particular to a distributed photovoltaic power generation steady-state and transient-state frequency coordination control method and system, and the method comprises the steps: monitoring the illumination radiance and the frequency deviation and frequency change rate tracked by a distributed photovoltaic phase-locked loop in real time, and processing the measured illumination radiance and frequency data through a calculation unit, as the input quantity of the multiple controllers, the output power is subjected to weighting and defuzzification processing, and then is smoothly connected to output a distributed photovoltaic active power adjustment instruction; by monitoring fluctuation and uncertainty of illumination radiance in real time, optimizing photovoltaic power generation efficiency and power grid frequency stability and adopting a fuzzy control technology, power grid steady-state and transient-state frequency deviation is comprehensively adjusted, frequency deviation is reduced in a steady state, load or power generation changes are quickly responded in a transient state, and severe frequency fluctuation is restrained. The active support of the distributed power supply to the power grid is realized, and the frequency response capability and safety stability of the power system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a control method and system for steady-state transient frequency coordination of distributed photovoltaic power generation. Background Art

[0002] With the introduction of the "dual carbon" strategy, clean and low-carbon photovoltaic power generation continues to develop, and its penetration rate in the power system is getting higher and higher. In the future, the power generation of new energy sources, mainly wind power and photovoltaic power, will account for more than half of the load. However, photovoltaic power generation is characterized by volatility and uncertainty. Changes in its output will cause unbalanced power in the power system, which will in turn cause fluctuations in the system frequency, increasing the difficulty of frequency control. At the same time, distributed photovoltaic power is connected to the distribution network through grid-connected converters. Due to the lack of rotors of traditional synchronous machines, it is impossible to suppress power fluctuations on a large scale by changing the rotor kinetic energy when power is unbalanced, that is, the equivalent inertia of photovoltaic power generation is low. Therefore, if not controlled, a very high proportion of photovoltaic power grid connection will significantly reduce the frequency response capability of the distribution network, bringing challenges to the safe and stable operation of the distribution network.

[0003] Traditional distributed photovoltaic control strategies mainly include MPPT control, virtual inertia control, active power-frequency droop control, etc. MPPT control does not provide frequency regulation function because it only focuses on maximum power output and has no spare capacity to cope with fluctuations in grid frequency. The latter two types of control strategies do not fully consider the fluctuation and uncertainty of light radiation, resulting in poor control effect when light conditions change. Virtual inertia control usually only considers the instantaneous deviation of frequency, which is not enough to cope with rapid or large changes in grid frequency; droop control is usually based on a linear relationship, and the adjustment is not flexible or responsive when the grid frequency deviation is large or changes rapidly, and it may not be possible to completely eliminate the frequency deviation in steady state.

[0004] In summary, by real-time monitoring of light radiation and the frequency deviation and frequency change rate of the distributed photovoltaic phase-locked loop, the output power of the photovoltaic power generation system is comprehensively adjusted using fuzzy control technology, thereby optimizing the steady-state and transient frequency performance of the power grid, improving the frequency response capability and safety and stability of the power system, and solving the problem of grid frequency control caused by the volatility and uncertainty of photovoltaic power generation. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the technical problem to be solved by the present invention is: for different control scenarios and requirements of transient and steady-state power grids, light radiation, power grid system frequency deviation and frequency change rate are used as inputs to construct a multiple controller based on fuzzy control technology, and the outputs of the multiple controllers are weighted and defuzzified to achieve the goal of having optimal regulation performance in both steady-state and transient processes, thereby improving the frequency response capability of the power system and enhancing the safety and stability of the system.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: a control method for steady-state transient frequency coordination of distributed photovoltaic power generation, comprising: real-time monitoring of light radiation, frequency deviation and frequency change rate tracked by a distributed photovoltaic phase-locked loop; using the measured light radiation, frequency and data calculated by a frequency deviation and frequency change rate calculation unit as input quantities of multiple controllers; weighting the output power of the multiple controllers, defuzzifying them, and then smoothly connecting them to output active power adjustment instructions for distributed photovoltaics.

[0008] As a preferred solution of the control method for steady-state transient frequency coordination of distributed photovoltaic power generation described in the present invention, wherein: the light irradiance includes obtaining data using monitoring equipment and a data processing unit;

[0009] The monitoring device uses a radiometric sensor to sense the real-time light radiation of the photovoltaic power generation area;

[0010] The data processing unit converts the sensed light radiance into a numerical value of a control strategy.

[0011] As a preferred solution of the control method for steady-state transient frequency coordination of distributed photovoltaic power generation described in the present invention, the radiance sensor includes a photodiode and a photocell, and converts the optical signal into an electrical signal, which is expressed as:

[0012]

[0013] in, represents the light radiation of the i-th distributed photovoltaic at time t, represents the rate of change of the light radiation of the i-th distributed photovoltaic at time t, represents the rate of change of the light radiation of the i-th distributed photovoltaic at time t-1, Δt 1 Indicates the time interval for sampling the rate of change of light radiance.

[0014] As a preferred solution of a control method for steady-state transient frequency coordination of distributed photovoltaic power generation described in the present invention, wherein: the frequency deviation tracked by the distributed photovoltaic phase-locked loop includes a frequency measurement unit and a frequency deviation calculation unit;

[0015] The frequency measurement unit is used to measure the real-time frequency of distributed photovoltaic phase-locked loop tracking;

[0016] The frequency deviation calculation unit is used to calculate the deviation between the measured frequency and the rated frequency, which is expressed as:

[0017] Δf(t)=f pll (t)-f N

[0018] Among them, Δf(t) represents the frequency deviation of the system at time t, f pll (t) represents the tracking frequency of the distributed photovoltaic phase-locked loop at time t, f N Indicates the rated power of the system.

[0019] As a preferred solution of the control method for steady-state transient frequency coordination of distributed photovoltaic power generation described in the present invention, the frequency change rate is expressed as:

[0020] df(t)=(Δf(t)-f(t-Δt 2 )) / Δt 2

[0021] Among them, df(t) represents the frequency change rate of the distributed photovoltaic phase-locked loop tracking at time t, Δf(t) represents the frequency deviation of the system at time t, and f(t-Δt 2 ) represents the system t-Δt 2 Frequency deviation at time t, Δt 2 Indicates the time interval for frequency sampling.

[0022] As a preferred solution of the control method for steady-state transient frequency coordination of distributed photovoltaic power generation described in the present invention, wherein: the multi-controller includes three fuzzy controllers: fuzzy controller I, fuzzy controller II and fuzzy controller III;

[0023] The fuzzy controller I, when the frequency changes in the direction of small, the system load exceeds the generator output and changes to a larger place, that is, the output of distributed photovoltaic should be increased; when the light radiation changes in the direction of small, the output upper limit of distributed photovoltaic changes in the direction of small, that is, the output of distributed photovoltaic should be reduced;

[0024] The fuzzy controller II, when the rate of change of the light radiation is negative, the light radiation decreases; according to the fuzzy controller I, the output of the distributed photovoltaic decreases, causing power fluctuations in the power grid;

[0025] The fuzzy controller III, when the grid load decreases and the frequency change rate is positive, according to the fuzzy controllers I and II, the output of distributed photovoltaic decreases, the response time is slow, and the grid frequency increases.

[0026] As a preferred solution of the control method for steady-state transient frequency coordination of distributed photovoltaic power generation described in the present invention, the active power adjustment instruction of the distributed photovoltaic power generation includes defuzzifying fuzzy controllers I to III, which is expressed as:

[0027]

[0028] i=1,2,3

[0029] k 1 +k 2 +k 3 =1

[0030] Among them, γ represents the total active power output of the photovoltaic controller, k i represents the weight coefficient of fuzzy controller i, γ i represents the photovoltaic active power output of fuzzy controller i;

[0031] The final continuous output of distributed photovoltaics is expressed as:

[0032]

[0033] Among them, P PV (t) represents the final continuous output power control value of distributed photovoltaic, Δt 3 represents the interval value of sampling time, γ(t j ) represents the total active power output coefficient of the photovoltaic controller at time j, γ(t j+1 ) represents the total active power output coefficient of the photovoltaic controller at time j+1, (tt j ) represents the time difference between the current time and time j, ρ represents the backup coefficient, which is 0.9, Pr ated Indicates the active power reference value of the system.

[0034] Another object of the present invention is to provide a control system for steady-state transient frequency coordination of distributed photovoltaic power generation, including monitoring equipment for real-time monitoring of light radiation and frequency deviation, a calculation unit for calculating frequency deviation and frequency change rate, and multiple controllers based on fuzzy control technology. By weighting and defuzzifying the output power of multiple controllers, the optimal adjustment of the photovoltaic power generation system under different lighting conditions and grid frequency changes is achieved, thereby improving the grid frequency response capability and system stability.

[0035] In order to solve the above technical problems, the present invention provides the following technical solutions: a control system for steady-state transient frequency coordination of distributed photovoltaic power generation, comprising: a monitoring module, a calculation module and a control module;

[0036] The monitoring module monitors the light radiation, the frequency deviation and the frequency change rate of the distributed photovoltaic phase-locked loop tracking in real time;

[0037] The calculation module uses the measured light radiance, frequency and data calculated by the frequency deviation and frequency change rate calculation unit as input quantities of the multi-controller;

[0038] The control module weights and defuzzifies the output powers of multiple controllers, performs smooth connection, and outputs an active power adjustment instruction for distributed photovoltaics.

[0039] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of the control method for steady-state transient frequency coordination of distributed photovoltaic power generation are implemented as described above.

[0040] 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 control method for steady-state transient frequency coordination of distributed photovoltaic power generation as described above are implemented.

[0041] Beneficial effects of the present invention: Dynamic adjustment of light radiation: By real-time monitoring of the light radiation in the photovoltaic power generation area, the fluctuation and uncertainty of the light radiation can be dynamically considered. This monitoring and adjustment mechanism enables the distributed photovoltaic power generation system to adapt to changes in light conditions and optimize power generation efficiency and grid frequency stability.

[0042] Optimize the steady-state and transient frequency performance of the power grid: Fuzzy control technology is used to comprehensively adjust the steady-state and transient frequency deviations of the power grid. In the steady state, the system can reduce the frequency deviation and maintain the stability of the power grid; in the transient state, the controller quickly responds to changes in load or power generation, quickly adjusts the photovoltaic output, and effectively suppresses the sharp fluctuations in the power grid frequency.

[0043] Active support of distributed power sources to the power grid: By building a multi-controller based on fuzzy control technology, the distributed photovoltaic power generation system actively supports the power grid frequency. Through real-time monitoring and intelligent control, distributed power sources can participate in grid regulation more effectively, improve the frequency response capability and safety and stability of the entire power system, and provide more flexible and reliable support for the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0045] Figure 1 A flow chart of a method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation provided by an embodiment of the present invention.

[0046] Figure 2 A dual-machine test system diagram of a distributed photovoltaic power generation steady-state transient frequency coordination control method provided by an embodiment of the present invention.

[0047] Figure 3 A membership function diagram of a fuzzy controller I for a control method for steady-state transient frequency coordination of distributed photovoltaic power generation provided by an embodiment of the present invention.

[0048] Figure 4 A membership function diagram of a fuzzy controller II for a control method for steady-state transient frequency coordination of distributed photovoltaic power generation provided by an embodiment of the present invention.

[0049] Figure 5 A membership function diagram of a fuzzy controller III for a control method for steady-state transient frequency coordination of distributed photovoltaic power generation provided by an embodiment of the present invention.

[0050] Figure 6 A frequency response diagram of a system under different control conditions of a distributed photovoltaic power generation steady-state transient frequency coordination control method provided by an embodiment of the present invention.

[0051] Figure 7 A power output curve diagram under different control systems of a distributed photovoltaic power generation steady-state transient frequency coordination control method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0053] Example 1, reference Figure 1 , is an embodiment of the present invention, which provides a control method for steady-state transient frequency coordination of distributed photovoltaic power generation, including:

[0054] S1: Real-time monitoring of light radiation, frequency deviation and frequency change rate of distributed photovoltaic phase-locked loop tracking.

[0055] It should be noted that the light radiation includes the use of monitoring equipment to obtain data and data processing units;

[0056] The monitoring equipment uses a radiometric sensor to sense the real-time light radiation in the photovoltaic power generation area;

[0057] The data processing unit converts the sensed light radiance into a numerical value of the control strategy.

[0058] Furthermore, the radiometric sensor includes a photodiode and a photocell, which converts the optical signal into an electrical signal, which is expressed as:

[0059]

[0060] in, represents the light radiation of the i-th distributed photovoltaic at time t, represents the rate of change of the light radiation of the i-th distributed photovoltaic at time t, represents the rate of change of the light radiation of the i-th distributed photovoltaic at time t-1, Δt 1 Indicates the time interval for sampling the rate of change of light radiance.

[0061] S2: The measured light radiance, frequency and data calculated by the frequency deviation and frequency change rate calculation unit are used as input quantities of the multi-controller.

[0062] It should be noted that the frequency deviation tracked by the distributed photovoltaic phase-locked loop includes a frequency measurement unit and a frequency deviation calculation unit;

[0063] Frequency measurement unit, used to measure the real-time frequency of distributed photovoltaic phase-locked loop tracking;

[0064] The frequency calculation unit is used to calculate the deviation between the measured frequency and the rated frequency, expressed as:

[0065] Δf(t)=f pll (t)-f N

[0066] Among them, Δf(t) represents the frequency deviation of the system at time t, f pll (t) represents the tracking frequency of the distributed photovoltaic phase-locked loop at time t, f N Indicates the rated power of the system.

[0067] Furthermore, the rate of change is expressed as:

[0068] df(t)=(Δf(t)-f(t-Δt 2 )) / Δt 2

[0069] Among them, df(t) represents the frequency change rate of the distributed photovoltaic phase-locked loop tracking at time t, Δf(t) represents the frequency deviation of the system at time t, and f(t-Δt 2 ) represents the system t-Δt 2 Frequency deviation at time t, Δt 2 Indicates the time interval for frequency sampling.

[0070] S3: The output powers of multiple controllers are weighted, defuzzified, and then smoothly connected to output the active power adjustment instructions of distributed photovoltaics.

[0071] It should be noted that the multiple controller consists of three fuzzy controllers, namely, fuzzy controller I, fuzzy controller II and fuzzy controller III;

[0072] In fuzzy controller I, the fuzzy rules corresponding to the scenario are expressed as follows: when the frequency changes in the direction of small, the system load exceeds the generator output and changes in the direction of large, that is, the output of distributed photovoltaics should be increased; when the light radiation changes in the direction of small, the upper limit of the output of distributed photovoltaics changes in the direction of small, that is, the output of distributed photovoltaics should be reduced. The fuzzy rules and membership functions of fuzzy control I are determined by the scenario;

[0073] In fuzzy controller II, the fuzzy rule corresponding to the scenario is expressed as follows: when the rate of change of light radiation is negative, the light radiation decreases; according to the fuzzy rule of fuzzy controller I, the output of distributed photovoltaics decreases, causing power fluctuations in the power grid. In order to maintain the power balance of the system, it is necessary to add fuzzy rule II to slightly increase the output of distributed photovoltaics, avoiding the sudden change of photovoltaic output due to the sudden change of light radiation, which is similar to adding "inertia" to the change of light radiation affecting photovoltaic output; the impact of frequency on distributed photovoltaic output is the same as fuzzy controller I, and the fuzzy rules and membership functions of fuzzy control II are determined by the scenario;

[0074] In fuzzy controller III, the fuzzy rule corresponding scenario is expressed as follows: when the grid load decreases and the frequency change rate is a large positive value, according to the fuzzy rules of fuzzy controllers I and II, after a period of time, the output of distributed photovoltaics decreases, the response time is slow, and the grid frequency increases. In order to maintain the transient frequency stability of the grid and maintain power balance, it is necessary to add fuzzy rules III to quickly increase the output of distributed photovoltaics and suppress the unbalanced power caused by load changes, simulating the "inertia" of virtual inertia control; the impact of light radiation on distributed photovoltaic output is the same as fuzzy controller I, and the fuzzy rules and membership functions of fuzzy control III are determined by the scenario.

[0075] Furthermore, the active power adjustment instruction of the distributed photovoltaic includes defuzzifying the fuzzy controllers I to III, which is expressed as:

[0076]

[0077] i=1,2,3

[0078] k 1 +k 2 +k 3 =1

[0079] Among them, γ represents the total active power output of the photovoltaic controller, k i represents the weight coefficient of fuzzy controller i, γ i represents the photovoltaic active power output of fuzzy controller i.

[0080] Furthermore, in order to ensure the continuity of distributed photovoltaic output, a straight line is used for smooth connection, and the final continuous output of distributed photovoltaic is expressed as:

[0081]

[0082] Among them, P PV (t) represents the final continuous output power control value of distributed photovoltaic, Δt 3 represents the interval value of sampling time, γ(t j ) represents the total active power output coefficient of the photovoltaic controller at time j, γ(t j+1 ) represents the total active power output coefficient of the photovoltaic controller at time j+1, (tt j ) represents the time difference between the current time and time j, ρ represents the backup coefficient, which is 0.9, P rated Indicates the active power reference value of the system.

[0083] The above is a schematic scheme of a control method for steady-state transient frequency coordination of a distributed photovoltaic power generation in this embodiment. It should be noted that the technical scheme of the system of the control method for steady-state transient frequency coordination of a distributed photovoltaic power generation is the same as the technical scheme of the control method for steady-state transient frequency coordination of a distributed photovoltaic power generation described above. The details of the technical scheme of the control system for steady-state transient frequency coordination of a distributed photovoltaic power generation in this embodiment that are not described in detail can all be referred to the description of the technical scheme of the control method for steady-state transient frequency coordination of a distributed photovoltaic power generation described above.

[0084] In this embodiment, a control system for steady-state transient frequency coordination of distributed photovoltaic power generation is characterized by comprising: a monitoring module, a calculation module and a control module;

[0085] The monitoring module monitors the light radiation, the frequency deviation and the frequency change rate of the distributed photovoltaic phase-locked loop tracking in real time;

[0086] The calculation module uses the measured light radiance, frequency and data calculated by the frequency deviation and frequency change rate calculation unit as input quantities of the multi-controller;

[0087] The control module weights and defuzzifies the output powers of multiple controllers, performs smooth connection, and outputs an active power adjustment instruction for distributed photovoltaics.

[0088] This embodiment further provides a computing device, which is applicable to a method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation, including:

[0089] A memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement a control method for steady-state transient frequency coordination of distributed photovoltaic power generation as proposed in the above embodiment.

[0090] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, a control method for steady-state transient frequency coordination of distributed photovoltaic power generation is implemented as proposed in the above embodiment.

[0091] The storage medium proposed in this embodiment and the control method for steady-state transient frequency coordination of distributed photovoltaic power generation proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0092] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0093] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0094] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0095] Example 2, reference Figure 2-Figure 7 , is an embodiment of the present invention. This embodiment provides a control method for steady-state transient frequency coordination of distributed photovoltaic power generation. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0096] Build as Figure 2 The dual-machine system shown does not consider the influence of light radiation, reserves 10% of the reserve, and examines the system frequency characteristics under droop control, virtual inertia droop control and fuzzy control strategies. Among them, PV is distributed photovoltaic, SG is synchronous generator, the system power reference value is 100kW, and the active power consumed by load 1 and load 2 is 150kW and 20kW respectively.

[0097] The main parameters of the dual-machine system are shown in Table 1 and Table 2.

[0098] Table 1 Distributed photovoltaic PV simulation parameters

[0099]

[0100] Table 2 Simulation parameters of synchronous generator SG

[0101]

[0102] The fuzzy rules and membership functions of fuzzy control I are shown in Table 3 and Figure 3 shown.

[0103] Table 3 Fuzzy rules of fuzzy controller I

[0104]

[0105] The fuzzy rules and membership functions of fuzzy controller II are shown in Table 4 and Figure 4 shown.

[0106] Table 4 Fuzzy rules of fuzzy controller II

[0107]

[0108] The fuzzy rules and membership functions of fuzzy controller III are shown in Table 5 and Figure 5 shown.

[0109] Table 5 Fuzzy rules of fuzzy controller III

[0110]

[0111] Table 3, Table 4, Table 5, Figure 3 , Figure 4 as well as Figure 5 middle:

[0112] NB (Negative Big): A value very close to 1 but less than 1, used to indicate a very large but still negative quantity.

[0113] NM (Negative Medium): A value close to 0.5 but less than 0.5, used to indicate that a quantity is in a medium but negative state.

[0114] NS (Negative Small): A value very close to 0 but slightly greater than 0, used to indicate a very small but still negative quantity.

[0115] PB (Positive Big): A value very close to 1 (completely positive), used to indicate a very large or very positive state.

[0116] PM (Positive Medium): A value close to 0.5, used to indicate that a quantity is in a medium or neutral state.

[0117] PS (Positive Small): A value very close to 0, used to indicate a state where a quantity is very small or almost non-existent.

[0118] ZO (Zero): A point with a value of 0, used to represent a state where a quantity does not exist at all or is completely inactive.

[0119] According to fuzzy rules I and III, when the light radiation is very high or very low, it will become the main factor controlling the photovoltaic output. At this time, the photovoltaic output has little to do with the system frequency. Therefore, the light radiation is taken as 600W / m 2 and 1000W / m 2 The former doubles the rated active power to 100kW, which is convenient for comparing the frequency regulation capability with the other two control strategies, so as to intuitively reflect the frequency regulation capability of the fuzzy control system. The latter takes a rated active power of 50kW, which is consistent with the other two control strategies, reflecting the fact that the fuzzy control is insensitive to frequency under sufficient light conditions.

[0120] At t = 5s, load 2 is added, and the grid frequency, photovoltaic power output power and synchronous generator output power are obtained as follows: Figure 6 , Figure 7 shown.

[0121] Depend on Figure 6 , Figure 7 It can be seen that:

[0122] When photovoltaic power generation uses a light radiation of 600W / m 2 When fuzzy control is used, on the one hand, at the moment of power surge, the frequency suddenly drops, and the fuzzy controller III adds more active power than the traditional virtual inertia droop control to suppress the frequency drop. The lowest frequency point is higher than the traditional droop control and virtual inertia droop control, and the transient characteristics are optimal. On the other hand, in steady state, the system frequency is lower due to the newly added load. The fuzzy controllers I and II control the photovoltaic and synchronous generators to output more active power than the traditional droop control and virtual inertia droop control. Therefore, the steady-state frequency deviation is smaller than the traditional droop control and virtual inertia droop control, and the steady-state characteristics are also optimal.

[0123] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation, characterized by: include: Real-time monitoring of light radiation, frequency deviation and frequency change rate of distributed photovoltaic phase-locked loop tracking; The measured light irradiance, frequency and data calculated by the frequency deviation and frequency change rate calculation unit are used as input quantities of the multi-controller; The output powers of multiple controllers are weighted, defuzzified, and smoothly connected to output the active power adjustment instructions of distributed photovoltaics.

2. A method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation according to claim 1, characterized in that: The light radiance includes obtaining data using monitoring equipment and a data processing unit; The monitoring device uses a radiometric sensor to sense the real-time light radiation of the photovoltaic power generation area; The data processing unit converts the sensed light radiance into a numerical value of a control strategy.

3. A method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation as claimed in claim 2, characterized in that: The radiometric sensor includes a photodiode and a photocell, which converts the optical signal into an electrical signal, which is expressed as: in, represents the light radiation of the i-th distributed photovoltaic at time t, represents the rate of change of the light radiation of the i-th distributed photovoltaic at time t, It represents the rate of change of the light radiance of the i-th distributed photovoltaic at time t-1, and Δt1 represents the time interval for sampling the rate of change of the light radiance.

4. A method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation as claimed in claim 3, characterized in that: The frequency deviation tracked by the distributed photovoltaic phase-locked loop includes a frequency measurement unit and a frequency deviation calculation unit; The frequency measurement unit is used to measure the real-time frequency of distributed photovoltaic phase-locked loop tracking; The frequency deviation calculation unit is used to calculate the deviation between the measured frequency and the rated frequency, which is expressed as: Δf(t)=f pll (t)-f N Among them, Δf(t) represents the frequency deviation of the system at time t, f pll (t) represents the tracking frequency of the distributed photovoltaic phase-locked loop at time t, f N Indicates the rated power of the system.

5. A method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation as claimed in claim 4, characterized in that: The frequency change rate is expressed as: df(t)=(Δf(t)-f(t-Δt2)) / Δt2 Among them, df(t) represents the frequency change rate of the distributed photovoltaic phase-locked loop tracking at time t, Δf(t) represents the frequency deviation of the system at time t, f(t-Δt2) represents the frequency deviation of the system at time t-Δt2, and Δt2 represents the time interval of frequency sampling.

6. A method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation as claimed in claim 5, characterized in that: The multi-controller comprises three fuzzy controllers: fuzzy controller I, fuzzy controller II and fuzzy controller III; In the fuzzy controller I, when the frequency changes in a small direction, the system load exceeds the generator output, which means that the output of distributed photovoltaics should be increased; when the light radiation changes in a small direction, the upper limit of the output of distributed photovoltaics changes in a small direction, which means that the output of distributed photovoltaics should be reduced; The fuzzy controller II, when the rate of change of the light radiance is negative, the light radiance decreases; According to fuzzy controller I, the output of distributed photovoltaics decreases, causing power fluctuations in the power grid; The fuzzy controller III, when the grid load decreases and the frequency change rate is positive, according to the fuzzy controllers I and II, the output of the distributed photovoltaic decreases, the response time is slow, and the grid frequency increases.

7. A method for controlling steady-state transient frequency coordination of distributed photovoltaic power generation according to claim 6, characterized in that: The distributed photovoltaic active power adjustment instruction includes defuzzifying fuzzy controllers I to III, which is expressed as: i＝1,2,3 k1+k2+k3=1 Among them, γ represents the total active power output of the photovoltaic controller, k i represents the weight coefficient of fuzzy controller i, γ i represents the photovoltaic active power output of fuzzy controller i; The final continuous output of distributed photovoltaics is expressed as: Among them, P PV (t) represents the final continuous output power control value of distributed photovoltaic, Δt3 represents the interval value of sampling time, γ(t j ) represents the total active power output coefficient of the photovoltaic controller at time j, γ(t j+1 ) represents the total active power output coefficient of the photovoltaic controller at time j+1, (tt j ) represents the time difference between the current time and time j, ρ represents the backup coefficient, which is 0.9, P rated Indicates the active power reference value of the system.

8. A system based on a distributed photovoltaic power generation steady-state transient frequency coordination control method according to any one of claims 1 to 7, characterized in that: include: Monitoring module, calculation module and control module; The monitoring module monitors the light radiation, the frequency deviation and the frequency change rate of the distributed photovoltaic phase-locked loop tracking in real time; The calculation module uses the measured light radiance, frequency and data calculated by the frequency deviation and frequency change rate calculation unit as input quantities of the multi-controller; The control module weights and defuzzifies the output powers of multiple controllers, performs smooth connection, and outputs an active power adjustment instruction for distributed photovoltaics.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a distributed photovoltaic power generation steady-state transient frequency coordination control method according to any one of claims 1 to 7 are implemented.

10. 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 a distributed photovoltaic power generation steady-state transient frequency coordination control method according to any one of claims 1 to 7 are implemented.

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