Control method for energy-storage-free photovoltaic virtual synchronous generator cluster

Abstract

The invention relates to the technical field of electric power automation, in particular to a control method for an energy-storage-free photovoltaic virtual synchronous generator cluster, which comprises the following steps of: calculating an active standby capacity distribution coefficient according to the maximum output active power and the total expected active standby capacity of the energy-storage-free photovoltaic virtual synchronous generator cluster; calculating the active standby capacity of each PV-VSG according to the active standby capacity distribution coefficient and the maximum output active power of each PV-VSG; according to the active standby capacity of each PV-VSG, calculating an active frequency modulation coefficient of each PV-VSG; calculating an output active power reference value of each PV-VSG according to the active standby capacity and the maximum output active power of each PV-VSG; and based on the active frequency modulation coefficient and the output active power reference value of each PV-VSG, controlling the non-energy storage type photovoltaic virtual synchronous generator cluster. Through the control method, the active standby capacity of each PV-VSG can be dynamically allocated, and inertia and primary frequency modulation support of a power grid can be effectively realized.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power automation, and in particular to a control method for a photovoltaic virtual synchronous generator cluster without energy storage. Background Art

[0002] In recent years, the scale of photovoltaic power generation in the power system has developed rapidly, and the penetration rate has increased significantly. Photovoltaic power generation systems not only have the responsibility of supplying clean energy, but also have to participate in the frequency regulation of the power system to a certain extent and bear the responsibility for the safety and stability of the power system to a certain extent.

[0003] At present, the main technical solution to meet the requirements of photovoltaic power generation participating in power system frequency regulation and providing active reserve capacity for the power system is photovoltaic virtual synchronous generator (PV-VSG), which is mainly divided into two types: with energy storage and without energy storage. PV-VSG with energy storage uses the capacity of the energy storage system to achieve active reserve. The active reserve capacity of the PV-VSG cluster with energy storage is equivalent to the capacity of the energy storage system. The active reserve capacity is allocated according to the actual energy storage system capacity of each PV-VSG, and the physical meaning is simple and intuitive. PV-VSG without energy storage uses photovoltaic power reduction control (PRC) to achieve active reserve, and the active reserve capacity is dynamically allocated by the photovoltaic power reduction control parameters of each PV-VSG. At present, there is a lack of allocation and control methods for the active reserve capacity of PV-VSG clusters without energy storage. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a control method for a photovoltaic virtual synchronous generator cluster without energy storage, which dynamically allocates the active reserve capacity of each PV-VSG according to the real-time photovoltaic output and the total expected active reserve capacity of the photovoltaic virtual synchronous generator cluster without energy storage, effectively realizing the inertia and primary frequency regulation support of the power grid.

[0005] The present invention is achieved by adopting the following technical solutions:

[0006] A control method for a photovoltaic virtual synchronous generator cluster without energy storage, comprising the following steps:

[0007] Step S1. Calculate the active reserve capacity allocation coefficient k according to the maximum output active power of the non-storage photovoltaic virtual synchronous generator cluster and the total expected active reserve capacity;

[0008] Step S2. Calculate the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity allocation coefficient k and the maximum output active power of each photovoltaic virtual synchronous generator PV-VSG i ;

[0009] Step S3: Based on the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i , calculate the active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi ; According to the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i And the maximum output active power, calculate the output active power reference value P of each photovoltaic virtual synchronous generator PV-VSG Ni ;

[0010] Step S4. Based on the active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi And the output active power reference value P Ni , to control the photovoltaic virtual synchronous generator cluster without energy storage.

[0011] The calculation method of active reserve capacity allocation coefficient k is:

[0012]

[0013] In the formula, is the total expected active reserve capacity of the photovoltaic virtual synchronous generator cluster without energy storage, ΔP i ′ is the expected active reserve capacity of the ith photovoltaic virtual synchronous generator PV-VSG, P mppi is the maximum output active power that can be generated by the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, ..., n, n is the number of photovoltaic virtual synchronous generators PV-VSG in the photovoltaic virtual synchronous generator cluster without energy storage.

[0014] Active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i The calculation method is:

[0015] ΔP i =kP mppi

[0016] In the formula, ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, ..., n; P mppi is the maximum output active power that the i-th photovoltaic virtual synchronous generator PV-VSG can generate; k is the active reserve capacity allocation coefficient.

[0017] Active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi The calculation method is:

[0018]

[0019] In the formula, fN is the rated operating frequency of the power system, f min is the lower frequency limit that the non-storage photovoltaic virtual synchronous generator cluster can respond to in one frequency regulation; ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG.

[0020] Active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi The specific calculation method is:

[0021]

[0022] In the formula, is the total expected active reserve capacity of the photovoltaic virtual synchronous generator cluster without energy storage, P mppi is the maximum output active power that can be generated by the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, ..., n, n is the number of photovoltaic virtual synchronous generators PV-VSG in the photovoltaic virtual synchronous generator cluster without energy storage; f N is the rated operating frequency of the power system, f min It is the lower limit of the frequency that can be responded to by the primary frequency regulation of the photovoltaic virtual synchronous generator PV-VSG cluster without energy storage.

[0023] The output active power reference value P of each photovoltaic virtual synchronous generator PV-VSG Ni The calculation method is:

[0024] P Ni =P mppi -ΔP i

[0025] Where P Ni At rated frequency f N The active power reference value output by the next ith photovoltaic virtual synchronous generator PV-VSG when it has active standby; P mppi is the maximum output active power that the i-th photovoltaic virtual synchronous generator PV-VSG can generate, i = 1, 2, ..., n; ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG.

[0026] The step S1 also includes step S0: determining the maximum output active power that can be generated by each photovoltaic virtual synchronous generator PV-VSG of the n photovoltaic virtual synchronous generator clusters without energy storage and its photovoltaic array port voltage according to the proposed maximum power value estimation of the photovoltaic system; detecting whether the maximum output active power changes, if so, returning to execute S0; if not, entering step S1.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The present invention dynamically allocates the active reserve capacity and active frequency modulation coefficient of each photovoltaic virtual synchronous generator PV-VSG through the real-time photovoltaic output and the total expected active reserve capacity of the non-storage photovoltaic virtual synchronous generator cluster. When the system frequency fluctuates, it can not only provide inertial support for the frequency of the power grid, but also increase the active power in proportion to the maximum active power emitted by each photovoltaic virtual synchronous generator PV-VSG in real time to provide primary frequency modulation support to the power grid, thereby effectively realizing the inertia and primary frequency modulation support for the power grid.

[0029] 2. The present invention selects the two parameters of active reserve capacity and active frequency modulation coefficient to achieve the maximum output active power P mppi A larger photovoltaic virtual synchronous generator PV-VSG provides more active power generation when the grid frequency fluctuates, that is, it provides more primary frequency regulation support. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, wherein:

[0031] Figure 1 It is a schematic diagram of the process of the present invention;

[0032] Figure 2 It is a structural schematic diagram of a photovoltaic virtual synchronous generator cluster without energy storage in the present invention;

[0033] Figure 3 This is a schematic diagram of photovoltaic power reduction control in the present invention;

[0034] Figure 4 is the active power P of the i-th PV-VSG in the present invention xi With frequency f x relationship;

[0035] Figure 5 The topological structure of two active standby photovoltaic virtual synchronous generators in parallel in the present invention;

[0036] Figure 6 This is a simulation waveform diagram of the power grid frequency dropping by 0.05Hz in the present invention;

[0037] Figure 7 This is a simulation waveform diagram of the power grid frequency rising by 0.05 Hz in the present invention. DETAILED DESCRIPTION

[0038] Example 1

[0039] As a basic implementation mode of the present invention, the present invention includes a control method for a photovoltaic virtual synchronous generator cluster without energy storage, including the following steps:

[0040] Step S1. Calculate the active reserve capacity allocation coefficient according to the maximum output active power of the non-energy storage photovoltaic virtual synchronous generator cluster and the total expected active reserve capacity.

[0041] Step S2: Calculate the active reserve capacity of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity allocation coefficient and the maximum output active power of each photovoltaic virtual synchronous generator PV-VSG.

[0042] Step S3. Calculate the active frequency modulation coefficient of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity of each photovoltaic virtual synchronous generator PV-VSG; calculate the output active power reference value of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity and maximum output active power of each photovoltaic virtual synchronous generator PV-VSG.

[0043] Step S4: Based on the active frequency modulation coefficient and output active power reference value of each photovoltaic virtual synchronous generator PV-VSG, the photovoltaic virtual synchronous generator cluster without energy storage is controlled.

[0044] Example 2

[0045] As a preferred embodiment of the present invention, the present invention includes a control method for a photovoltaic virtual synchronous generator cluster without energy storage, comprising the following steps:

[0046] Step S1. Calculate the active reserve capacity allocation coefficient k according to the maximum output active power of the non-storage photovoltaic virtual synchronous generator cluster and the total expected active reserve capacity:

[0047]

[0048] In the formula, is the total expected active reserve capacity of the photovoltaic virtual synchronous generator cluster without energy storage, ΔP i ′ is the expected active reserve capacity of the ith photovoltaic virtual synchronous generator PV-VSG, P mppi is the maximum output active power that can be generated by the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, ..., n, n is the number of photovoltaic virtual synchronous generators PV-VSG in the photovoltaic virtual synchronous generator cluster without energy storage.

[0049] Step S2. Calculate the active reserve capacity of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity allocation coefficient and the maximum output active power of each photovoltaic virtual synchronous generator PV-VSG:

[0050] ΔP i =kP mppi

[0051] In the formula, ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, …, n.

[0052] Step S3. Calculate the active frequency modulation coefficient of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity of each photovoltaic virtual synchronous generator PV-VSG and the power-frequency characteristic equation of the virtual synchronous generator:

[0053]

[0054] In the formula, f N is the rated operating frequency of the power system, f min k is the lower limit of the frequency that the non-storage photovoltaic virtual synchronous generator cluster can respond to in one frequency regulation; fi is the active frequency regulation coefficient of the i-th photovoltaic virtual synchronous generator PV-VSG.

[0055] According to the active reserve capacity and the maximum output active power of each photovoltaic virtual synchronous generator PV-VSG, the output active power reference value of each photovoltaic virtual synchronous generator PV-VSG is calculated.

[0056] Step S4: Based on the active frequency modulation coefficient and output active power reference value of each photovoltaic virtual synchronous generator PV-VSG, the photovoltaic virtual synchronous generator cluster without energy storage is controlled.

[0057] Example 3

[0058] As another preferred embodiment of the present invention, the present invention includes a control method for a photovoltaic virtual synchronous generator cluster without energy storage, comprising the following steps:

[0059] Step S 0. According to the proposed maximum power value estimation of the photovoltaic system, the maximum output active power that each photovoltaic virtual synchronous generator PV-VSG of the n photovoltaic virtual synchronous generator clusters without energy storage can generate and its photovoltaic array port voltage are determined; detect whether the maximum output active power changes, if so, return to execute S0; if not, enter step S1.

[0060] Step S1. Calculate the active reserve capacity allocation coefficient according to the maximum output active power of the non-energy storage photovoltaic virtual synchronous generator cluster and the total expected active reserve capacity.

[0061] Step S2: Calculate the active reserve capacity of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity allocation coefficient and the maximum output active power of each photovoltaic virtual synchronous generator PV-VSG.

[0062] Step S3. Calculate the active frequency modulation coefficient of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity of each photovoltaic virtual synchronous generator PV-VSG. Calculate the output active power reference value of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity and maximum output active power of each photovoltaic virtual synchronous generator PV-VSG.

[0063] Step S4: Based on the active frequency modulation coefficient and output active power reference value of each photovoltaic virtual synchronous generator PV-VSG, the photovoltaic virtual synchronous generator cluster without energy storage is controlled.

[0064] Example 4

[0065] As the best embodiment of the present invention, the present invention includes a control method for a photovoltaic virtual synchronous generator cluster without energy storage. The structure of the photovoltaic virtual synchronous generator cluster without energy storage can be as shown in the attached manual. Figure 2 As shown in the figure, the non-storage photovoltaic virtual synchronous generator cluster consists of photovoltaic array i (i = 1 ~ n), DC-DC converter i (i = 1 ~ n), DC / AC converter i (i = 1 ~ n) and distribution network. Among them, the DC-DC converter is controlled by photovoltaic power reduction control (Power Reserve Control, PRC), and the DC / AC converter is controlled by virtual synchronous generator (Virtual Synchronous Generator, VSG).

[0066] Photovoltaic Maximum Power Point Tracking (MPPT) is an automatic optimization process for the maximum power point A of the photovoltaic system, while photovoltaic power reserve control (PRC) can make the photovoltaic system work at a position away from the maximum power point. Figure 3 Instructions attached Figure 3 In, P mppi Under MPPT control, at rated frequency f N The maximum active output power of the next ith photovoltaic virtual synchronous generator PV-VSG; U mppi At rated frequency f NThe maximum output power P of the next photovoltaic virtual synchronous generator PV-VSG mppi When the photovoltaic array outputs voltage; P Ni At rated frequency f N The active power reference value output by the next ith photovoltaic virtual synchronous generator PV-VSG when it has active standby; U Ni At rated frequency f N The active power output of the next ith PV-VSG is P Ni When the photovoltaic array outputs voltage; ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG.

[0067] Based on this, refer to the instructions for Figure 1 , the control method of the present invention comprises the following steps:

[0068] Step S 0. According to the proposed maximum power point estimate (MPPE) of the photovoltaic system, the maximum output active power P that each photovoltaic virtual synchronous generator PV-VSG of the n photovoltaic virtual synchronous generator cluster without energy storage can generate is determined. mppi Its PV array terminal voltage U mppi . Check whether the maximum output active power changes. If it does, return to execute S0; if not, continue to run and enter step S1.

[0069] Step S1. Calculate the active reserve capacity allocation coefficient k according to the maximum output active power of the non-storage photovoltaic virtual synchronous generator cluster and the total expected active reserve capacity:

[0070]

[0071] In the formula, is the total expected active reserve capacity of the photovoltaic virtual synchronous generator cluster without energy storage, ΔP i ′ is the expected active reserve capacity of the ith photovoltaic virtual synchronous generator PV-VSG, P mppi is the maximum output active power that can be generated by the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, ..., n, n is the number of photovoltaic virtual synchronous generators PV-VSG in the photovoltaic virtual synchronous generator cluster without energy storage.

[0072] Step S2. According to the active reserve capacity allocation coefficient k and the maximum output active power P of each photovoltaic virtual synchronous generator PV-VSG mppi , calculate the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i :

[0073] ΔP i =kP mppi

[0074] In the formula, ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, …, n.

[0075] Step S3: Based on the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i , calculate the active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi According to the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i And the maximum output active power P mppi , calculate the output active power reference value P of each photovoltaic virtual synchronous generator PV-VSG Ni .

[0076] The power-frequency characteristic of the i-th virtual synchronous generator is its output power P xi With frequency f x The relationship between x The actual operating frequency of the power system, as shown in the attached manual. Figure 4 As shown, the frequency f of the i-th virtual synchronous generator is x And the output active power P xi The active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi The calculation method is:

[0077]

[0078] In the formula, f N is the rated operating frequency of the power system, f min k is the lower limit of the frequency that the primary frequency regulation of the PV-VSG cluster without energy storage can respond to; fi is the active frequency modulation coefficient of the i-th photovoltaic virtual synchronous generator PV-VSG. The negative sign reflects the droop characteristic, indicating that the output power of PV-VSG decreases with increasing frequency and increases with decreasing frequency.

[0079] Furthermore, by combining the expression of active reserve capacity allocation coefficient and the expression of active reserve capacity, the active frequency modulation coefficient k can be obtained: fi The expression is:

[0080]

[0081] The calculation method of the output active power reference value of each photovoltaic virtual synchronous generator PV-VSG is:

[0082] P Ni =P mppi -ΔP i

[0083] Where P Ni At rated frequency f N The active power reference value output by the i-th photovoltaic virtual synchronous generator PV-VSG when it has active standby.

[0084] Step S4. Based on the active frequency modulation coefficient and output active power reference value of each photovoltaic virtual synchronous generator PV-VSG, the non-energy storage photovoltaic virtual synchronous generator cluster is controlled, that is, the operation of each photovoltaic virtual synchronous generator PV-VSG is controlled by the virtual synchronous generator (VSG).

[0085] Refer to the instruction manual Figure 4 , the output power P of the i-th PV-VSG xi The constraints are:

[0086] 0<P xi ≤P mppi

[0087] The output active power P of the i-th PV-VSG with active reserve xi for:

[0088] P xi =P Ni +k fi (f N -f x )

[0089] Combined with active frequency modulation coefficient k fi From the expression, we can know that the active frequency modulation coefficient k of the i-th PV-VSG fi Its active reserve capacity ΔP i It is proportional to the maximum output active power P that can be emitted under MPPT control. mppi Therefore, the control strategy proposed in the present invention realizes the control target of dynamically allocating active reserve capacity according to the real-time photovoltaic output optimization.

[0090] Example 5

[0091] As a specific embodiment of the present invention, the present invention includes a control method for a photovoltaic virtual synchronous generator cluster without energy storage. Figure 2 The topological structure of the corresponding simulation model is established in Matlab / Simulink as shown in the attached manual. Figure 5 As shown, the main parameters of the two PV-VSG simulation systems are shown in Table 1.

[0092] Table 1

[0093]

[0094] Table 1 Maximum output active power P mppi It is obtained through the MPPE link based on the external environment at this time. At this time, the system's expected active reserve capacity is set The system is the lower frequency limit f that the PV-VSG cluster without energy storage can respond to in one frequency regulation min =49.9Hz.

[0095] According to the expression of active reserve capacity allocation coefficient k, k = 0.1 can be calculated; according to the active reserve capacity ΔP i The expression can be calculated to get ΔP1 = 2kW, ΔP2 = 4kW; according to the active frequency modulation coefficient k fi The expression for k can be calculated f1 =20kW / Hz, k f2 =40kW / Hz; according to the output active power reference value P Ni The expression for P is calculated N1 =18kW, P N2 =36kW.

[0096] According to the calculated active frequency modulation coefficient and output active power reference value of the two PV-VSGs, the photovoltaic virtual synchronous generator cluster without energy storage is controlled through the virtual synchronous generator (VSG) control strategy.

[0097] Working condition I: system frequency drops by 0.05Hz

[0098] Simulation as the instruction manual Figure 6 As shown in the figure, the simulation time is 2s. At 1s, the grid frequency suddenly drops from 50.0Hz to 49.95Hz, as shown in the figure. Figure 6 As shown in (a), due to the effect of inertia, the system frequency drop curve is relatively smooth; when it is checked that the system frequency drops beyond the dead zone, the two PV-VSG photovoltaic systems release the standby active power, the active standby capacity of PV-VSG1 drops from 2kW to 1kW, and the active standby capacity of PV-VSG2 drops from 4kW to 2kW. The active standby rates of the two PV-VSGs drop from 10% to 5%, and the active standby capacity is still optimized according to the real-time output of each PV-VSG photovoltaic; the active output of PV-VSG1 increases from 18kW to 19kW, and the active output of PV-VSG2 increases from 36kW to 38kW. The active power increase is optimized according to the real-time output of each PV-VSG photovoltaic, thereby increasing the photovoltaic output active power and participating in the primary frequency regulation of the power grid. The output power is shown in Figure 6 (b) and (c) are shown in the pre-set configuration.

[0099] Working condition II: System frequency rises by 0.05Hz

[0100] Simulation as the instruction manual Figure 7 As shown in the figure, the simulation time is 2s. At 1s, the grid frequency suddenly rises from 50.0Hz to 50.05Hz. Figure 7 As shown in (a), due to the effect of inertia, the system frequency rise line is relatively smooth; when the system frequency rises, the active reserve capacity of PV-VSG1 increases from 2kW to 3kW, and the active reserve capacity of PV-VSG2 increases from 4kW to 6kW. The active reserve rates of both PV-VSGs increase from 10% to 15%, and the active reserve capacity is still optimized according to the real-time output of each PV-VSG photovoltaic power plant; the active output of PV-VSG1 decreases from 18kW to 17kW, and the active output of PV-VSG2 decreases from 36kW to 34kW. The active reduction is optimized according to the real-time output of each PV-VSG photovoltaic power plant, thereby reducing the photovoltaic output active power and participating in the primary frequency regulation of the power grid. The output power is shown in Figure 7 (b) and (c) are shown in the pre-set configuration.

[0101] From the above simulation results, it can be concluded that when the active reserve capacity of the two PV-VSGs is dynamically optimized and allocated according to the real-time output of photovoltaic power, when the system frequency drops or rises by 0.05Hz, the active reserve capacity of the two PV-VSGs decreases or increases by 1kW and 2kW, which is still dynamically optimized and allocated according to the real-time output of photovoltaic power; the active power increased or decreased by the two PV-VSGs is 1kW and 2kW respectively, which is also dynamically optimized and allocated according to the real-time output of photovoltaic power. It can well realize the optimal allocation of active power and thus realize the primary frequency regulation function of the system, verifying the effectiveness of the proposed example of optimal allocation of active reserve capacity of PV-VSG cluster without energy storage based on photovoltaic output.

[0102] In summary, after reading the present invention document, ordinary technicians in this field can make various other corresponding transformation schemes based on the technical scheme and technical concept of the present invention without creative mental labor, which all fall within the scope of protection of the present invention.

Claims

1. A control method for a photovoltaic virtual synchronous generator cluster without energy storage, characterized in that: The following steps are involved: Step S1. Calculate the active reserve capacity allocation coefficient k according to the maximum output active power of the non-storage photovoltaic virtual synchronous generator cluster and the total expected active reserve capacity; Step S2. Calculate the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG according to the active reserve capacity allocation coefficient k and the maximum output active power of each photovoltaic virtual synchronous generator PV-VSG i ; Step S3: Based on the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i , calculate the active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi ; According to the active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i And the maximum output active power, calculate the output active power reference value P of each photovoltaic virtual synchronous generator PV-VSG Ni ; Step S4. Based on the active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi And the output active power reference value P Ni , to control the photovoltaic virtual synchronous generator cluster without energy storage.

2. A control method for a photovoltaic virtual synchronous generator cluster without energy storage according to claim 1, characterized in that: The calculation method of active reserve capacity allocation coefficient k is: In the formula, is the total expected active reserve capacity of the photovoltaic virtual synchronous generator cluster without energy storage, ΔP i ′ is the expected active reserve capacity of the ith photovoltaic virtual synchronous generator PV-VSG, P mppi is the maximum output active power that can be generated by the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, ..., n, n is the number of photovoltaic virtual synchronous generators PV-VSG in the photovoltaic virtual synchronous generator cluster without energy storage.

3. A control method for a photovoltaic virtual synchronous generator cluster without energy storage according to claim 1, characterized in that: Active reserve capacity ΔP of each photovoltaic virtual synchronous generator PV-VSG i The calculation method is: ΔP i =kP mppi Where ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, ..., n; P mppi is the maximum output active power that the i-th photovoltaic virtual synchronous generator PV-VSG can generate; k is the active reserve capacity allocation coefficient.

4. A control method for a photovoltaic virtual synchronous generator cluster without energy storage according to claim 1, characterized in that: Active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi The calculation method is: In the formula, f N is the rated operating frequency of the power system, f min is the lower frequency limit that the non-storage photovoltaic virtual synchronous generator cluster can respond to in one frequency regulation; ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG.

5. A control method for a photovoltaic virtual synchronous generator cluster without energy storage according to claim 4, characterized in that: Active frequency modulation coefficient k of each photovoltaic virtual synchronous generator PV-VSG fi The specific calculation method is: In the formula, is the total expected active reserve capacity of the photovoltaic virtual synchronous generator cluster without energy storage, P mppi is the maximum output active power that can be generated by the i-th photovoltaic virtual synchronous generator PV-VSG, i = 1, 2, ..., n, n is the number of photovoltaic virtual synchronous generators PV-VSG in the photovoltaic virtual synchronous generator cluster without energy storage; f N is the rated operating frequency of the power system, f min It is the lower limit of the frequency that can be responded to by the primary frequency regulation of the photovoltaic virtual synchronous generator PV-VSG cluster without energy storage.

6. A control method for a photovoltaic virtual synchronous generator cluster without energy storage according to claim 1, characterized in that: The output active power reference value P of each photovoltaic virtual synchronous generator PV-VSG Ni The calculation method is: P Ni =P mppi -ΔP i Where P Ni At rated frequency f N The active power reference value output by the next ith photovoltaic virtual synchronous generator PV-VSG when it has active standby; P mppi is the maximum output active power that the i-th photovoltaic virtual synchronous generator PV-VSG can generate, i = 1, 2, ..., n; ΔP i is the active reserve capacity of the i-th photovoltaic virtual synchronous generator PV-VSG.

7. A control method for a photovoltaic virtual synchronous generator cluster without energy storage according to any one of claims 1 to 6, characterized in that: The step S1 also includes step S0: determining the maximum output active power that can be generated by each photovoltaic virtual synchronous generator PV-VSG of the n photovoltaic virtual synchronous generator clusters without energy storage and its photovoltaic array port voltage according to the proposed maximum power value estimation of the photovoltaic system; detecting whether the maximum output active power changes, if so, returning to execute S0; if not, entering step S1.

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