A method for coordinating fault ride-through of multiple photovoltaic power sources

Abstract

This invention discloses a multi-photovoltaic power source fault ride-through coordination method belonging to the field of multi-photovoltaic power source technology. It includes the following steps: Step 1: Calculate the initial current command and update the operating status; Step 2: Calculate the reactive current deviation, then proceed to Step 3; Step 3: Iteratively update the reactive current deviation and the average operating status of the state variables, then proceed to Step 4; Step 4: Determine whether the average reactive current deviation is less than or equal to 0. If not, update the current command and operating status, and proceed to Step 2; if yes, proceed to Step 5; Step 5: Determine whether the maximum phase voltage is greater than or equal to 1.1 times the rated value. If not, end the process; if yes, proceed to Step 6; Step 6: Iteratively obtain the average voltage deviation, update the negative-sequence reactive current command, and proceed to Step 7; Step 7: Update the positive-sequence reactive current command, and proceed to Step 5. This invention is less affected by changes in network topology and has scalability.

Description

Technical Field

[0001] This invention relates to the field of multi-photovoltaic power source technology, and in particular to a multi-photovoltaic power source fault ride-through coordination method. Background Technology

[0002] As the proportion of photovoltaic (PV) power generation resources continues to increase, its grid connection and disconnection have a significant impact on grid stability. Fault ride-through strategies aim to improve the resilience of inverters during grid faults, maintain continuous grid connection during fault periods, and inject a certain amount of reactive power into the grid according to a predetermined plan. However, limited by the capacity of PV inverters, the increased reactive power generation from PV will inevitably lead to a reduction in active power output, potentially threatening system frequency stability. Furthermore, in the event of asymmetrical grid faults, since grid voltage and current typically contain positive and negative sequence components, PV power supplies based on inverter control structures may experience voltage and current exceeding limits and power oscillations. In severe cases, this can lead to cascading tripping of such equipment, disrupting grid stability. Therefore, improving the fault ride-through capability of PV is of great significance for enhancing the stability and reliability of new energy power systems.

[0003] Traditional low-voltage ride-through strategies have a relatively singular control objective and only specify the calculation methods for positive-sequence active and reactive currents, failing to fully leverage the inverter's flexible adjustment advantages. When used for asymmetrical fault ride-through, renewable energy power plants face a significant risk of grid disconnection. With further research, some scholars have proposed fault ride-through strategies that can achieve multi-objective coordinated control. However, these strategies still suffer from difficulties in suppressing voltage and current over-limit risks and weak frequency support capabilities. Furthermore, due to differences in inverter capacity, constraints, and instantaneous operating points, fault ride-through strategies applicable to a single photovoltaic power source cannot guarantee that the entire power plant operates at its optimal point, leaving grid-connected photovoltaic power plants still facing a certain risk of grid disconnection. For renewable energy grids with a high proportion of photovoltaic power, there is currently a lack of fault ride-through strategies that can achieve coordinated operation of multiple photovoltaic power sources. Therefore, it is necessary to propose a multi-photovoltaic power source fault ride-through coordination method based on a consensus algorithm to address these issues. Summary of the Invention

[0004] The purpose of this invention is to propose a multi-photovoltaic power source fault ride-through coordination method, characterized by the following steps:

[0005] Step 1: Calculate the initial current command based on the voltage drop depth and the photovoltaic system's own operating status, and update the operating status;

[0006] Step 2: Calculate the reactive current deviation i based on the current actual reactive current output and the standard required reactive current. need Then proceed to step 3;

[0007] Step 3: Iteratively update the reactive current deviation and operating state mean of the state variables according to the discrete consistency formula. After the iteration is completed, proceed to step 4.

[0008] Step 4: Determine if the average reactive current deviation is less than or equal to 0. If not, update the current command and operating status, and proceed to step 2; if yes, proceed to step 5.

[0009] Step 5: Determine whether the maximum phase voltage is greater than or equal to 1.1 times the rated value. If not, end the process; otherwise, proceed to step 6.

[0010] Step 6: Enter the discrete consistency process, iterate to obtain the average voltage deviation, update the negative sequence reactive current command, and then go to step 7;

[0011] Step 7: Update the positive sequence reactive current command according to the current limiting requirements, and then go to step 5.

[0012] The discrete consistency formula in step 3 is as follows:

[0013]

[0014] In the formula: x i For consistent state variables; k is the number of iterations; w ij The elements in the i-th row and j-th column of the weight matrix W are determined by the topology of the communication network; i = 1, 2, 3, ..., n; j = 1, 2, 3, ..., n.

[0015] The criterion for completing the iteration in step 3 is: the deviation between two consecutive sets of iteration values ​​satisfies...

[0016] |x i,k+1 -x i,k |<10 -2

[0017] In the formula: x i,k+1 Let x be the iteration value of the consistent state variable in this iteration. i,k This is the iteration value of the consistent state variable from the previous iteration.

[0018] The formula for updating the current command in step 4 is as follows:

[0019]

[0020]

[0021] In the formula, i q,new For the updated reactive current command, i q For the reactive current command before the update, Δi avg M represents the global average value of the reactive current deviation, and M represents the current operating mode of this node. avgi is the global average value of the operating mode. d,new This is the updated active current command.

[0022] The formula for obtaining the average voltage deviation in step 6 is as follows:

[0023]

[0024] In the formula, Δv i,k+1 The average voltage deviation obtained in this iteration is Δv. j,k Let w be the average voltage deviation obtained from the previous iteration at other nodes, N be the number of nodes in the system, and w be the average voltage deviation obtained from the previous iteration at other nodes. ij Let v be the element in the i-th row and j-th column of the weight matrix W. i,k+1 v is the maximum phase voltage at node i during this iteration. i,k This represents the maximum phase voltage of node i during the previous iteration.

[0025] The formula for updating the negative-sequence reactive current command in step 6 is as follows:

[0026]

[0027] In the formula, This is the negative-sequence reactive current command obtained in this iteration. The negative-sequence reactive current command obtained from the previous iteration, μ is a constant coefficient, and Δv i,k+1 This represents the average voltage deviation obtained in this iteration.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. This invention only needs to interact with its neighboring nodes, is less affected by changes in network topology, and has scalability.

[0030] 2. By coordinating active and reactive currents, while raising the voltage, a certain amount of active power output can be retained, reducing the risk of photovoltaic power sources disconnecting from the grid due to frequency exceeding limits.

[0031] 3. By coordinating the positive and negative sequence reactive currents, the voltage of the faulty phase can be increased while the voltage of the non-faulty phase can be prevented from overvoltage, and the phase current can be limited to the safe operating range.

[0032] 4. This invention can achieve coordinated control of multiple photovoltaic power sources, which can improve the photovoltaic fault ride-through capability while providing a certain voltage and frequency support to the power grid. Attached Figure Description

[0033] Figure 1 This is a simulation system diagram containing a photovoltaic power source connected to the grid;

[0034] Figure 2 This is a diagram showing the coordination of positive and negative sequence reactive currents.

[0035] Figure 3 This is a flowchart of the multi-photovoltaic power source fault ride-through coordination method of the present invention;

[0036] Figure 4 The three-phase voltage at the grid connection point in scenario one;

[0037] Figure 5 The three-phase voltage amplitude at the grid connection point in scenario one;

[0038] Figure 6 The positive and negative sequence voltage amplitudes at the grid connection point in scenario one;

[0039] Figure 7 The dq current value is for photovoltaic 1 in scenario one;

[0040] Figure 8 The dq current value is for photovoltaic 2 in scenario one;

[0041] Figure 9 The dq current value is for photovoltaic 3 in scenario one;

[0042] Figure 10 The dq current value is for photovoltaic 4 in scenario one;

[0043] Figure 11 This represents the power output value of Photovoltaic 1 in Scenario 1;

[0044] Figure 12 This represents the power output value of Photovoltaic 2 in Scenario 1.

[0045] Figure 13 This represents the power output value of Photovoltaic 3 in Scenario 1;

[0046] Figure 14 This represents the power output value of Photovoltaic 4 in Scenario 1.

[0047] Figure 15 The three-phase voltage at the grid connection point for scenario two;

[0048] Figure 16 The three-phase voltage amplitude at the grid connection point in scenario two;

[0049] Figure 17 The positive and negative sequence voltage amplitudes at the grid connection point in scenario two;

[0050] Figure 18 The dq current value is for photovoltaic 1 in scenario two;

[0051] Figure 19 The dq current value is for photovoltaic 2 in scenario two;

[0052] Figure 20 The dq current value is for photovoltaic 3 in scenario two;

[0053] Figure 21The dq current value is for photovoltaic 4 in scenario two;

[0054] Figure 22 The three-phase current values ​​are for Photovoltaic 1 in Scenario 2;

[0055] Figure 23 The three-phase current values ​​are for Photovoltaic 2 in Scenario 2;

[0056] Figure 24 The three-phase current values ​​are for photovoltaic module 3 in scenario two.

[0057] Figure 25 The three-phase current values ​​are for photovoltaic 4 in scenario two. Detailed Implementation

[0058] This invention proposes a multi-photovoltaic power source fault ride-through coordination method, which will be further described below with reference to the accompanying drawings and specific embodiments.

[0059] Figure 1 A simulation diagram of a grid-connected photovoltaic (PV) power supply system is provided. The output characteristics of the PV power supply under asymmetrical voltage dips are analyzed, and control objectives for the PV power supply under asymmetrical voltage dips are set. Details are as follows:

[0060] Under asymmetrical voltage drop, the output voltage of the photovoltaic inverter in the αβ coordinate system can be expressed as:

[0061]

[0062] In the formula: v + and v - Indicates positive and negative sequence voltages; V + and V - This represents the positive-sequence and negative-sequence voltage amplitudes. Similarly, the output current of a photovoltaic inverter can be expressed as:

[0063]

[0064] In the formula: i + and i - This indicates the positive-sequence and negative-sequence currents output by the inverter; and These are the amplitudes of the positive-sequence active and reactive current components and the negative-sequence active and reactive current components, respectively.

[0065] Control objectives of photovoltaic power sources under asymmetrical voltage sag:

[0066] 1. Active power output

[0067] When a high-proportion photovoltaic (PV) system experiences a fault, the traditional low-voltage ride-through strategy prioritizes voltage support, leading to a significant loss of active power and a corresponding decrease in frequency. To address this issue, this invention improves the reactive current calculation formula specified in the traditional strategy by considering the relationship between active and reactive power output from PV systems. Simultaneously, to fully utilize the capacity of the PV inverter, the invention prioritizes utilizing the idle capacity generated due to the randomness and intermittency of PV power output to support reactive power during the initial stage of a fault, thereby enhancing the active power output capability of the PV power supply during the fault period. The following section explains the coordination approach between active and reactive currents and the improvement to the reactive current calculation formula.

[0068] To improve the active power output capability of the photovoltaic power source during faults, this embodiment sets the maximum value of the reactive power reference current to 0.8I. N During a fault, reactive power output is still prioritized. This ensures voltage support while avoiding excessive reduction in active power. The improved method for calculating the reactive current reference value is as follows:

[0069]

[0070] In the formula, i q,ref This is the reference value for reactive current; I N U is the rated output current of the photovoltaic power source; U is the ratio of the actual voltage at the grid connection point of the photovoltaic power source to the rated voltage.

[0071] 2. Dynamic voltage support

[0072] Most power grid specifications do not specify requirements for negative-sequence current injection during asymmetrical faults; balanced positive-sequence control is a widely used strategy in industrial applications. However, under unbalanced voltage dips, injecting only positive-sequence reactive power may raise the voltage of the faulty phase while potentially causing overvoltage in the non-faulty phases, which could lead to grid disconnection of the photovoltaic power source in severe cases. In such situations, injecting appropriate negative-sequence current can limit overvoltage in the non-faulty phases. Therefore, to achieve dynamic voltage support, photovoltaic systems can consider injecting a certain amount of negative-sequence reactive current alongside positive-sequence reactive current into the grid.

[0073] 3. Current limiting

[0074] To ensure that the improved control strategy during fault ride-through does not cause the photovoltaic grid to disconnect due to overcurrent, the output current amplitude needs to be limited. After performing an inverse Clark transform on the photovoltaic inverter's output current formula, the three-phase current output by the photovoltaic power supply can be expressed as:

[0075]

[0076] Among them, I pL I pS I qL and I qS As an intermediate variable:

[0077]

[0078] In the formula: γ represents the phase difference between the positive and negative sequence currents. Under fault conditions, the maximum phase current limiting the output of the photovoltaic inverter is I. lim Then the three-phase currents must satisfy:

[0079] max(I a ,I b ,I c )≤I lim

[0080] To achieve the proposed control objective, a consensus algorithm and a fault ride-through strategy are combined. Adjacent photovoltaic systems exchange voltage deviation information, reactive current deviation information, and operating status information through a communication network. Then, a consensus algorithm is used to iteratively update the average value of the exchanged information, thereby obtaining the current command required by each power source.

[0081] Methods for coordinating active and reactive currents:

[0082] Under asymmetrical fault conditions, the average active power output of the photovoltaic power source can be expressed as:

[0083]

[0084] To simplify control, the negative-sequence active current is controlled to 0. Assume the active current command of the photovoltaic power source before the fault is... Positive sequence voltage is After the fault, the positive sequence voltage drops to As shown in the following formula, in order to keep the output active power constant, the active current should be adjusted to...

[0085]

[0086] Because power electronic devices have poor overcurrent tolerance, the output current of photovoltaic inverters is generally required to not exceed 1.25 times the rated current. By setting the current limit to 1 p.u., the initial active current reference value can be derived. for:

[0087]

[0088] In determining Then, the maximum reactive current i that the photovoltaic inverter can output at this time can be derived. q,max for:

[0089]

[0090] To fully utilize the capacity of the photovoltaic inverter, the initial reactive current i of each power source is controlled during the initial stage of a fault.q_ini =i q,max The reactive current required by the power grid standard is i. q,ref At this time, the reactive current of some power sources in the station still does not meet the grid standard requirements, and the reactive current deviation is:

[0091] i q,need =i q,ref -i q

[0092] After completing the above calculations, it is also necessary to determine the operating status of the photovoltaic power source. Let M represent the operating status of the photovoltaic system, and its formula is as follows:

[0093]

[0094] When the maximum reactive current i that the photovoltaic power source can output q,max When the reactive power output of the photovoltaic system is ≥0.8, it has reached its limit, M=1; when the maximum reactive current i that the photovoltaic system can output is... q,max If M < 0.8, it indicates that the photovoltaic system still has room to release reactive power, and M = 0.

[0095] After local calculations are completed, a consensus process begins, where adjacent photovoltaic (PV) power sources exchange reactive current deviation and operational mode iteration information. After several iterations, the state variables will converge to the average of their initial values, which is then fed to the local controller of the PV power source. Assume N is the total number of PV power sources in the site, and the global average value of the reactive current deviation Δi... q,avg It will converge uniformly to Global average value M of the operating mode avg It will converge uniformly to The convergence criterion is:

[0096] |x i,k+1 -x i,k |<10 -2

[0097] After obtaining the global average, if Δi q,avg If Δi is less than or equal to 0, it indicates that the voltage support provided by the substation meets the grid standard requirements; if Δi q,avg If the value is greater than 0, the reactive power generated by the photovoltaic power generation (M=0) will be used to balance the reactive current deviation within the power station. Based on the principle of evenly distributing the increased power generation, the current command update formula is:

[0098]

[0099]

[0100] will i q,needThe sum is evenly distributed among the photovoltaic power sources where M=0. If the reactive power margin of this photovoltaic power source is less than the required additional reactive power, its output is controlled to the maximum reactive current, and M becomes 1. The missing reactive power difference will be added to the other photovoltaic power sources where M is still 0 in the next calculation cycle.

[0101] Methods for coordinating positive and negative sequence reactive currents:

[0102] 1) Dynamic voltage support

[0103] The maximum three-phase voltage V after the fault max ={v a ,v b ,v c Considering that it should be controlled within 1.1 times the rated value, the initial voltage deviation can be obtained as follows:

[0104] Δv0=v max -1.1U n

[0105] Each photovoltaic power source obtains the voltage deviation at adjacent photovoltaic locations through communication, and derives the global average voltage deviation formula:

[0106]

[0107] In the formula, Δv i,k+1 The average voltage deviation obtained in this iteration is Δv. j,k Let w be the average voltage deviation obtained from the previous iteration at other nodes, N be the number of nodes in the system, and w be the average voltage deviation obtained from the previous iteration at other nodes. ij Let v be the element in the i-th row and j-th column of the weight matrix W. i,k+1 v is the maximum phase voltage at node i during this iteration. i,k Let be the maximum phase voltage at node i during the previous iteration. Based on the voltage deviation, the command formula for the negative sequence reactive current can be obtained:

[0108]

[0109] In the formula, This is the negative-sequence reactive current command obtained in this iteration. The negative-sequence reactive current command obtained from the previous iteration, μ is a constant coefficient, and Δv i,k+1 This represents the average voltage deviation obtained in this iteration. The above formula links the maximum phase voltage with the negative sequence reactive current, and the voltage deviation Δv directly affects the change in the negative sequence reactive current command.

[0110] 2) Current limiting

[0111] Due to the limitation of the maximum phase current, the positive and negative sequence reactive currents need to be coordinated. To fully utilize the inverter capacity, after calculating the negative sequence reactive current, it is necessary to... Figure 2The black solid line in the middle shows the distribution of positive and negative sequence reactive current.

[0112] Multi-PV Fault Ride Control Process:

[0113] The multi-photovoltaic fault ride-through control process based on consensus algorithm is as follows: Figure 3 As shown, the specific steps are as follows.

[0114] Step 1: Calculate the initial current command based on the voltage drop depth and the photovoltaic system's own operating status, and update the operating status.

[0115] Step 2: The local controller of the photovoltaic system calculates the reactive current deviation i based on the actual reactive current output and the standard required reactive current. need .

[0116] Step 3: After completing the local reactive current deviation calculation, enter the discrete consistency process, update the state variables reactive current deviation and operating status, and the iteration is completed when the deviation of two consecutive sets of iterative values ​​meets the convergence criterion.

[0117] Step 4: Determine whether the average reactive current deviation meets the standard requirements. If it does not, update the current command and operating status, and proceed to step 2; if it does, proceed to step 5.

[0118] Step 5: Determine if the maximum phase voltage meets the requirements. If it does, end the process; otherwise, proceed to step 6.

[0119] Step 6: Enter the discrete consistency process and update the negative sequence reactive current command.

[0120] Step 7: Update the positive sequence reactive current command according to the current limiting requirements, and return to step 5.

[0121] To verify the effectiveness of the proposed control strategy under different operating scenarios, a system was built based on Matlab / Simulink. Figure 1 The simulation system shown includes a photovoltaic power source connected to the grid. The initial active currents of the four photovoltaic cells are 1 p.u., 0 p.u., 0.5 pu and 0.8 pu, respectively. The specific parameter settings are shown in Table 1.

[0122] Table 1 Simulation parameter settings

[0123]

[0124] Two calculation examples were designed by changing the voltage drop of the grid-side bus, as shown in Table 2.

[0125] Table 2 Simulation Example Settings

[0126]

[0127] In the simulation, an asymmetrical voltage drop was set to occur at 0.1s, and the fault was cleared at 0.4s. To compare the control effects of the traditional low-voltage ride-through strategy with the proposed method, the photovoltaic system was set to use a reactive power priority and negative sequence current elimination control mode (traditional low-voltage ride-through control strategy) from 0.1 to 0.25s, and the control strategy was switched to the fault ride-through strategy of this invention at 0.25s.

[0128] In the simulation, the communication period between photovoltaic power sources is set to 2ms. Figure 1 The weight matrix of the communication topology in the diagram can be represented as:

[0129]

[0130] Scenario 1: Severe voltage drop and non-faulty phases are not overvoltaged

[0131] At 0.1s, a severe asymmetrical voltage drop (V) occurred on the grid-side bus. + =0.54pu, V - =0.2pu). By Figures 4 to 14 It can be seen that when using the traditional low-voltage ride-through control strategy (during the period of 0.1 to 0.25 seconds), due to the severe voltage drop, reactive power is prioritized for output, and the reference value of the positive-sequence active current of all photovoltaic cells is... The reactive current drops to 0 p.u., and the average output active power is zero. When using the control strategy of this invention (during 0.25 to 0.4 s), since the maximum reactive current demand is limited to 0.8 p.u., the positive sequence active current reference values ​​of PV1, PV3 and PV4 are... The voltage eventually stabilized around 0.6 pu, with an average active power of 0.336 pu. Using the proposed control strategy, the positive-sequence voltage only decreased slightly, from 0.54 pu to 0.52 pu, while the active power output of the photovoltaic power station increased from 0 kW to 504.3 kW. Therefore, the control algorithm of this invention, while ensuring voltage support, also has good frequency support capability, significantly improving the fault ride-through capability of photovoltaic systems.

[0132] Scenario 2: Voltage drop is not severe and overvoltage is not on the faulty phase.

[0133] At 0.1s, a slight asymmetrical voltage drop (V) occurred on the grid-side bus. + =0.73pu, V - =0.26pu). By Figures 18-21It is known that when using the traditional control strategy, the idle capacity of the photovoltaic inverter is not fully utilized; however, when using the strategy of this invention, the idle capacity of PV2 and PV3 is used first in the early stage of the fault. Since the reactive current output of PV2 and PV3 is 1.8pu, which is less than the total reactive current requirement of 2.24pu in the power station, PV1 and PV4 each generate an additional 0.22pu of reactive current to ensure that the reactive current output of the power station meets the standard requirements.

[0134] Figures 15-17 The graph compares the voltage improvement effects under two control methods. The positive and negative sequence reactive current coordination strategy of this invention is activated at 0.3s. By coordinating the positive and negative sequence reactive current output by the photovoltaic power source, this strategy reduces the maximum phase voltage at the grid connection point from 1.21pu to 1.1pu and the negative sequence voltage from 0.26pu to 0.22pu after a 50ms delay, thus reducing the risk of the photovoltaic power source disconnecting from the grid due to voltage exceeding limits. Simultaneously, [the following text appears to be a separate, unrelated sentence fragment: "...by..."] Figures 22-25 As can be seen, the maximum phase current output by photovoltaic power sources is limited to within 1 p.u. Therefore, photovoltaic power sources can safely and stably achieve fault ride-through.

[0135] This embodiment combines consensus theory and fault ride-through control to address the weak frequency support and voltage / current limit exceedance issues inherent in traditional low-voltage ride-through strategies using a distributed approach. It only requires interaction with adjacent nodes, is minimally affected by changes in network topology, and exhibits scalability. By coordinating active and reactive currents, it can raise the voltage while retaining a certain amount of active power output, reducing the risk of photovoltaic power sources disconnecting from the grid due to frequency limit exceedances. By coordinating positive and negative sequence reactive currents, it can raise the voltage of the faulty phase while preventing overvoltage in non-faulty phases and limiting phase currents to safe operating areas. It enables coordinated control of multiple photovoltaic power sources, improving photovoltaic fault ride-through capability while providing a certain level of voltage and frequency support to the grid.

Claims

1. A method for coordinating fault ride-through of multiple photovoltaic power sources, characterized in that, Includes the following steps: Step 1: Calculate the initial current command based on the voltage drop depth and the photovoltaic system's own operating status, and update the operating status; Step 2: Calculate the reactive current deviation i based on the current actual reactive current output and the standard required reactive current. need Then proceed to step 3; Step 3: Iteratively update the reactive current deviation and operating state mean of the state variables according to the discrete consistency formula. After the iteration is completed, proceed to step 4. Step 4: Determine if the average reactive current deviation is less than or equal to 0. If not, update the current command and operating status, and proceed to step 2; if yes, proceed to step 5. Step 5: Determine whether the maximum phase voltage is greater than or equal to 1.1 times the rated value. If not, end the process; otherwise, proceed to step 6. Step 6: Enter the discrete consistency process, iterate to obtain the average voltage deviation, update the negative sequence reactive current command, and then go to step 7; The formula for obtaining the average voltage deviation in step 6 is as follows: In the formula, Δv i,k+1 The average voltage deviation obtained in this iteration is Δv. j,k Let w be the average voltage deviation obtained from the previous iteration at other nodes, N be the number of nodes in the system, and w be the average voltage deviation obtained from the previous iteration at other nodes. ij Let v be the element in the i-th row and j-th column of the weight matrix W. i,k+1 v is the maximum phase voltage at node i during this iteration. i,k This represents the maximum phase voltage of node i during the previous iteration; The formula for updating the negative-sequence reactive current command in step 6 is as follows: In the formula, This is the negative-sequence reactive current command obtained in this iteration. The negative-sequence reactive current command obtained from the previous iteration, μ is a constant coefficient, and Δv i,k+1 This represents the average voltage deviation obtained in this iteration; Step 7: Update the positive sequence reactive current command according to the current limiting requirements, and then go to step 5.

2. The multi-photovoltaic power source fault ride-through coordination method according to claim 1, characterized in that, The discrete consistency formula in step 3 is as follows: In the formula: x i For consistent state variables; k is the number of iterations; w ij The elements in the i-th row and j-th column of the weight matrix W are determined by the topology of the communication network; i = 1, 2, 3, ..., n; j = 1, 2, 3, ..., n.

3. The multi-photovoltaic power source fault ride-through coordination method according to claim 1, characterized in that, The criterion for completing the iteration in step 3 is: the deviation between two consecutive sets of iteration values ​​satisfies... |x i,k+1 -x i,k |<10 -2 In the formula: x i,k+1 Let x be the iteration value of the consistent state variable in this iteration. i,k This is the iteration value of the consistent state variable from the previous iteration.

4. The multi-photovoltaic power source fault ride-through coordination method according to claim 1, characterized in that, The formula for updating the current command in step 4 is as follows: In the formula, i q,new For the updated reactive current command, i q For the reactive current command before the update, Δi avg M represents the global average value of the reactive current deviation, and M represents the current operating mode of the node. avg i is the global average value of the operating mode. d,new This is the updated active current command.

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