Distribution network real-time voltage control method based on fair excitation strategy

Abstract

The invention relates to a distribution network real-time voltage control method based on a fair excitation strategy. The method comprises the following steps: step 1, establishing a voltage regulation optimization comprehensive objective function with minimum network loss and voltage deviation of a distribution network; step 2, establishing a reactive power-voltage optimization control model of the variable coefficient of the photovoltaic inverter; step 3, establishing an active power-voltage reduction model of the photovoltaic inverter; 4, providing a fair incentive strategy; step 5, calculating the voltage and voltage deviation of the power distribution network by using the obtained electrical parameters of the power distribution network according to the reactive power required to be output by each photovoltaic inverter and the reduced active power obtained in the step 4, and substituting a calculation formula and a result into the target function established in the step 1; step 6, giving out constraint conditions of the voltage regulation optimization comprehensive objective function; and 7, solving a voltage fairness optimal strategy by using a particle swarm algorithm. According to the method, the fairness of active power reduction of each photovoltaic inverter can be guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of distribution network operation and analysis technology, and relates to a distribution network real-time voltage control method, in particular to a distribution network real-time voltage control method based on a fair incentive strategy. Background Art

[0002] At present, the number of household photovoltaic grid-connected to my country's medium and low voltage distribution networks is growing rapidly, and the grid-connected capacity is also increasing. Although the increase in photovoltaic penetration can alleviate the rapid depletion of fossil fuels and reduce carbon emissions from traditional power plants, it has created major technical challenges for the operation and control of distribution networks. A high proportion of photovoltaic access to the grid will cause power flow reverse transmission and voltage over-limit; at the same time, due to the strong uncertainty and volatility of photovoltaic output, node voltage fluctuations are frequent.

[0003] Traditional voltage regulation equipment, such as on-load tap-changing transformers and smart capacitors, can greatly adjust the voltage, but cannot suppress the rapid fluctuation of voltage. The voltage regulation process is slow, usually taking several hours or even days. Photovoltaic inverters are power electronic devices with high response speed and flexible reactive injection range. The response time is usually a few minutes or even seconds, which can effectively solve the problem of voltage fluctuation. Since photovoltaic inverters generally use maximum power point tracking power grid connection, the reactive voltage regulation ability is limited. When the power grid has a large voltage limit, it no longer has a significant regulation effect. At the same time, the resistance R in the distribution network is significantly greater than X. Reducing photovoltaic grid-connected power is a very simple and effective method to suppress network overvoltage, and can help reduce the active power flow in the line under overvoltage conditions, thereby reducing network losses. However, it is difficult to coordinate the active power reduction of different nodes, and it is difficult to balance fairness when executing reduction and compensation, and it is also difficult to explain the rationality of power reduction. Therefore, how to ensure the fairness of reactive power output and active power reduction of multiple photovoltaic inverters in the substation is an urgent problem to be solved.

[0004] In order to solve the above problems, the present invention proposes a real-time voltage control method for a distribution network based on a fair incentive strategy.

[0005] After searching, no prior art documents identical or similar to the present invention were found. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a real-time voltage control method for a distribution network based on a fair incentive strategy, which can ensure effective voltage control and equality of photovoltaic power reduction at each node.

[0007] The present invention solves the practical problem by adopting the following technical solutions:

[0008] A real-time voltage control method for a distribution network based on a fair incentive strategy comprises the following steps:

[0009] Step 1: Establish a comprehensive objective function for optimizing voltage regulation with minimum network loss and voltage deviation in the distribution network;

[0010] Step 2: Based on the comprehensive objective function established in step 1, a variable coefficient reactive-voltage optimization control model of the photovoltaic inverter is established;

[0011] Step 3: Based on the comprehensive objective function established in step 1, an active power-voltage reduction model of the photovoltaic inverter is established;

[0012] Step 4: Based on the reactive power-voltage optimization control model with variable coefficient of photovoltaic inverter established in step 2 and the active power-voltage reduction model of photovoltaic inverter established in step 3, a fair incentive strategy is proposed;

[0013] Step 5: According to the reactive power to be output by each photovoltaic inverter and the active power to be reduced obtained in step 4, the voltage and voltage deviation of the distribution network are calculated using the obtained electrical parameters of the distribution network, and the calculation formula and result are substituted into the objective function established in step 1;

[0014] Step 6: Give the constraint conditions of the voltage regulation optimization comprehensive objective function established in step 1;

[0015] Step 7: Based on the comprehensive objective function established in step 1 and the constraints given in step 6, the particle swarm algorithm is used to solve the optimal voltage fairness strategy.

[0016] Moreover, the specific steps of step 1 include:

[0017] (1) Establish a comprehensive objective function for optimizing voltage regulation with minimum distribution network loss and voltage deviation, and the constraint objective is the distribution network loss P Loss Minimum, each node voltage deviation value U DV Minimum:

[0018]

[0019] In the formula, i and j represent the starting and ending nodes of the line, N represents the number of system nodes, and U i , U j Indicates the voltage at the beginning and end of the line; cosθ ij represents the node voltage phase angle cosine, g ij Indicates line conductance; U N Indicates the node voltage rating; U max , U min Indicates the maximum and minimum values ​​of the node voltage.

[0020] (2) Assign weights to the above two objective functions respectively and form a comprehensive objective function f:

[0021] minf=α1P Loss +α2U DV (3)

[0022] α1+α2=1(4)

[0023] In the formula, α1 and α2 are weight coefficients, which can be selected according to the needs of distribution network optimization.

[0024] Moreover, the specific method of step 2 is:

[0025] The relationship between the reactive power and active power output of the photovoltaic inverter can be expressed as:

[0026]

[0027] Where: Q PV is the reactive power output by the photovoltaic inverter; S PV is the apparent power of the photovoltaic inverter; P PV is the active power of the photovoltaic inverter;

[0028] In the traditional constant coefficient voltage-reactive power droop control VVDC mode, the reactive power target value of the photovoltaic power station is calculated according to formula (6):

[0029] Q obj =Q0+K qv (U ref -U meas ) meas <U L or U meas >U H (6)

[0030] Where: Q obj is the reactive power target value of distributed photovoltaic, in per unit value; Q0 is the voltage of distributed photovoltaic grid connection point, U meas The corresponding work power is in per unit value; K qv is the reactive voltage droop control coefficient; U ref is the grid connection point voltage reference value, unit is per unit value; U H is the upper limit of the dead zone voltage; U L is the lower limit of the dead zone voltage.

[0031] In the variable coefficient VVDC mode, the droop coefficient should be proportional to its reactive power capacity:

[0032]

[0033] Where: Q i t maxis the maximum reactive power that the i-th PV inverter can provide at time t; n is the number of PV inverters in the area; α is set according to the reactive power demand.

[0034] Moreover, the specific method of step 3 is:

[0035] If the voltage U meas Lower than the upper limit of the allowable voltage U up When the photovoltaic power generation is connected to the grid according to the maximum power point tracking MPPT power; if the voltage of the grid-connected node exceeds the upper limit of the allowable voltage, the photovoltaic power generation will no longer be connected to the grid according to the MPPT power, but the photovoltaic grid-connected active power will be cut off according to the predetermined voltage-active power curve;

[0036] Calculate the active power reduction amount P according to the following formula: R .

[0037]

[0038] Where: β is the proportional coefficient, which can be set according to actual conditions.

[0039] Moreover, the specific method of step 4 is:

[0040] Ensure that the ratio of reactive power to active power output of each photovoltaic inverter is consistent. The consistency of the ratio of reactive power to active power is calculated according to the following formula:

[0041]

[0042] In the formula, S PVi and S PVj are the apparent powers of the i-th and j-th PV inverters respectively; Q PVi and Q PVj are the reactive powers output by the i-th and j-th PV inverters respectively; and are the active power cut by the i-th and j-th PV inverters respectively; and are the maximum active powers of the i-th and j-th PV inverters respectively.

[0043] Moreover, the specific steps of step 5 include:

[0044] (1) Obtain the electrical parameters of the distribution network, including topology, line length and unit length impedance, node load and photovoltaic capacity;

[0045] (2) Establish a voltage deviation calculation model to calculate the voltage deviation before and after photovoltaic access:

[0046] Now assume that the voltage of node i before connecting to distributed photovoltaic is U i0 , the voltage after connecting to distributed photovoltaic is Ui1 ,but

[0047]

[0048] Where P and Q are the active and reactive power generated by the photovoltaic power source respectively; P L and Q L are the local active and reactive loads of the grid-connected point respectively; R and X are the line resistance and reactance.

[0049] The second term on the right side of the equal sign in formula (10) is much smaller than the first term, so after ignoring the second term, the voltage change at the grid connection point can be approximately expressed as:

[0050]

[0051] Furthermore, the constraints of step 6 include:

[0052] 1) AC power flow equation constraints

[0053]

[0054] Where: P Gi and Q Gi are the active power and reactive power injected by node i respectively; P Li and Q Li are the active power and reactive power of the load at node i respectively; δ ij is the phase difference between the voltage vectors at node i and node j; G ij and B ij are the conductance and susceptance of the line between node i and node j respectively; n is the total number of nodes in the power grid.

[0055] 2) Voltage and current scenario constraints

[0056] U i,min ≤U i ≤U i,max (13)

[0057] I i,min ≤I i ≤I i,max (14)

[0058] Where: U i,max , U i,min Respectively represent the upper and lower limits of the voltage of the grid node i; I i,max ,I i,min They represent the upper and lower limits of the current at the grid node i respectively.

[0059] 3) Active and reactive power constraints of photovoltaic inverters

[0060]

[0061] Where: Q PV,min , Q PV,max Respectively represent the minimum and maximum reactive power of the photovoltaic inverter; P PV,min , P PV,max Indicates the minimum and maximum active power of the PV inverter.

[0062] Moreover, the specific steps of step 7 include:

[0063] (1) The population size of the voltage fairness optimal strategy is set. At the same time, the position information of the mth particle is composed of grid parameters, distributed photovoltaic parameters and load parameters, and the particle position and speed are initialized.

[0064] (2) Calculate the voltage deviation and network loss of the distribution network as the fitness value of the particle. Evaluate the fitness values ​​of all particles, select the global optimal position of the particle and the individual extreme point and save them separately;

[0065] (3) Determine the maximum number of iterations or convergence accuracy. If the requirements of formula (1) and formula (2) are met, the process ends. If the requirements are not met, update the position and velocity information of the particle and repeat steps (1) and (2).

[0066] (4) After the iteration, the active power reduction and output reactive power value of each photovoltaic inverter based on the fair incentive strategy are output.

[0067] Advantages and beneficial effects of the present invention:

[0068] The present invention proposes a real-time voltage control method for distribution network based on fair incentive strategy, which ensures effective voltage control and equality of photovoltaic power reduction at each node, making reactive output and active power reduction and incentive schemes easier to implement. Compared with traditional voltage regulation strategies, the present invention has a faster response speed and can continuously adjust the power output of photovoltaic inverters. For low-voltage distribution networks, the voltage regulation effect of the present invention is more significant than that of the simple reactive-voltage control mode. At present, the active-voltage control mode cannot guarantee the fairness of active power reduction of each photovoltaic inverter. The sampling fair incentive strategy of the present invention can solve this problem well. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a flow chart of the distribution network voltage control strategy based on fair incentives of the present invention. DETAILED DESCRIPTION

[0070] The following is a further description of the embodiments of the present invention:

[0071] A real-time voltage control method for distribution network based on fair incentive strategy, such as Figure 1As shown, the following steps are included:

[0072] Step 1: Establish a comprehensive objective function for optimizing voltage regulation with minimum network loss and voltage deviation in the distribution network;

[0073] The specific steps of step 1 include:

[0074] (1) Establish a comprehensive objective function for optimizing voltage regulation with minimum distribution network loss and voltage deviation, and the constraint objective is the distribution network loss P Loss Minimum, each node voltage deviation value U DV Minimum:

[0075]

[0076] In the formula, i and j represent the starting and ending nodes of the line, N represents the number of system nodes, and U i , U j Indicates the voltage at the beginning and end of the line; cosθ ij represents the node voltage phase angle cosine, g ij Indicates line conductance; U N Indicates the node voltage rating; U max , U min Indicates the maximum and minimum values ​​of the node voltage.

[0077] (2) To facilitate subsequent solution analysis, the above two objective functions are weighted respectively to form a comprehensive objective function f:

[0078] minf=α1P Loss +α2U DV (3)

[0079] α1+α2=1(4)

[0080] In the formula, α1 and α2 are weight coefficients, which can be selected according to the needs of distribution network optimization.

[0081] Step 2: Based on the comprehensive objective function established in step 1, a variable coefficient reactive-voltage optimization control model of the photovoltaic inverter is established;

[0082] The specific method of step 2 is:

[0083] The relationship between the reactive power and active power output of the photovoltaic inverter can be expressed as:

[0084]

[0085] Where: Q PV is the reactive power output by the photovoltaic inverter; S PV is the apparent power of the photovoltaic inverter; P PV is the active power of the photovoltaic inverter;

[0086] In the traditional fixed coefficient voltage-var (UQ) droop control (VVDC) mode, the reactive power target value of the photovoltaic power station is calculated according to formula (6):

[0087] Q obj =Q0+K qv (U ref -U meas ) meas <U L or U meas >U H (6)

[0088] Where: Q obj is the reactive power target value of distributed photovoltaic, in per unit value (pu); Q0 is the voltage of distributed photovoltaic grid connection point, U meas The corresponding work power is expressed in per unit (pu); K qv is the reactive voltage droop control coefficient; U ref U is the grid connection point voltage reference value (rated voltage can be taken), unit is per unit value (pu); H is the upper limit of the dead zone voltage; U L It is the lower limit of the dead zone voltage.

[0089] In the variable coefficient VVDC mode, the droop coefficient should be proportional to its reactive power capacity:

[0090]

[0091] Where: is the maximum reactive power that the i-th PV inverter can provide at time t; n is the number of PV inverters in the area; α is set according to the reactive power demand.

[0092] The variable coefficient reactive-voltage optimization control model of the photovoltaic inverter calculates the total reactive power of the distribution network based on the difference between the voltage target value and the measured value. Since the optimization target in step 1 includes voltage deviation and network loss, the voltage value of the grid is required, which can be calculated based on the grid parameters and the photovoltaic active and reactive power.

[0093] Step 3: Based on the comprehensive objective function established in step 1, an active power-voltage reduction model of the photovoltaic inverter is established;

[0094] The specific method of step 3 is:

[0095] If the voltage U meas Lower than the upper limit of the allowable voltage U upWhen the photovoltaic power generation is connected to the grid according to the maximum power point tracking (MPPT) power; if the voltage of the grid-connected node exceeds the upper limit of the allowable voltage, the photovoltaic power generation is no longer connected to the grid according to the MPPT power, but the photovoltaic grid-connected active power is cut according to the predetermined voltage-active power curve; the active power reduction amount P can be calculated according to the following formula R .

[0096]

[0097] Where: β is the proportional coefficient, which can be set according to actual conditions.

[0098] The purpose of establishing the active power-voltage reduction model of the photovoltaic inverter is to calculate the active power reduction. Since the optimization objectives in step 1 include voltage deviation and network loss, the voltage value of the grid is required, which can be calculated based on the grid parameters and the photovoltaic active and reactive power.

[0099] Step 4: Based on the variable coefficient reactive-voltage optimization control model of the photovoltaic inverter established in step 2 and the active-voltage reduction model of the photovoltaic inverter established in step 3, a fair incentive strategy is proposed in order to fairly distribute the total reactive power and active power in steps 2 and 3 to each photovoltaic inverter;

[0100] The specific method of step 4 is:

[0101] Considering the voltage fairness of photovoltaic inverters, it is necessary to ensure that the ratio of reactive power to active power output of each photovoltaic inverter is consistent. The consistency of the ratio of reactive power to active power can be calculated according to the following formula:

[0102]

[0103] In the formula, S PVi and S PVj are the apparent powers of the i-th and j-th PV inverters respectively; Q PVi and Q PVj are the reactive powers output by the i-th and j-th PV inverters respectively; and are the active power cut by the i-th and j-th PV inverters respectively; and are the maximum active powers of the i-th and j-th PV inverters respectively.

[0104] Step 5: According to the reactive power to be output by each photovoltaic inverter and the active power to be reduced obtained in step 4, the voltage and voltage deviation of the distribution network are calculated using the obtained electrical parameters of the distribution network, and the calculation formula and result are substituted into the objective function established in step 1;

[0105] The specific steps of step 5 include:

[0106] (1) Obtain the electrical parameters of the distribution network, including topology, line length and unit length impedance, node load and photovoltaic capacity;

[0107] (2) Establish a voltage deviation calculation model to calculate the voltage deviation before and after photovoltaic access:

[0108] Now assume that the voltage of node i before connecting to distributed photovoltaic is U i0 , the voltage after connecting to distributed photovoltaic is U i1 ,but

[0109]

[0110] Where P and Q are the active and reactive power generated by the photovoltaic power source respectively; P L and Q L are the local active and reactive loads of the grid-connected point respectively; R and X are the line resistance and reactance.

[0111] The second term on the right side of the equal sign in formula (10) is much smaller than the first term, so after ignoring the second term, the voltage change at the grid connection point can be approximately expressed as:

[0112]

[0113] Step 6: Give the constraint conditions of the voltage regulation optimization comprehensive objective function established in step 1;

[0114] 1) AC power flow equation constraints

[0115]

[0116] Where: P Gi and Q Gi are the active power and reactive power injected by node i respectively; P Li and Q Li are the active power and reactive power of the load at node i respectively; δ ij is the phase difference between the voltage vectors at node i and node j; G ij and B ij are the conductance and susceptance of the line between node i and node j respectively; n is the total number of nodes in the power grid.

[0117] 2) Voltage and current scenario constraints

[0118] U imin ≤U i ≤U imax (13)

[0119] I i,min ≤I i ≤Ii,max (14)

[0120] Where: U i,max , U i,min Respectively represent the upper and lower limits of the voltage of the grid node i; I i,max ,I i,min They represent the upper and lower limits of the current at the grid node i respectively.

[0121] 3) Active and reactive power constraints of photovoltaic inverters

[0122]

[0123] Where: Q PV,min , Q PV,max Respectively represent the minimum and maximum reactive power of the photovoltaic inverter; P PV,min , P PV,max Indicates the minimum and maximum active power of the PV inverter.

[0124] Step 7: Based on the comprehensive objective function established in step 1 and the constraints given in step 6, the particle swarm algorithm is used to solve the voltage fairness optimal strategy;

[0125] The specific steps of step 7 include:

[0126] (1) The population size of the voltage fairness optimal strategy is set. At the same time, the position information of the mth particle is composed of grid parameters, distributed photovoltaic parameters and load parameters, and the particle position and speed are initialized.

[0127] (2) Calculate the voltage deviation and network loss of the distribution network as the fitness value of the particle. Evaluate the fitness values ​​of all particles, select the global optimal position of the particle and the individual extreme point and save them separately;

[0128] (3) Determine the maximum number of iterations or convergence accuracy. If the requirements of formula (1) and formula (2) are met, the process ends. If the requirements are not met, update the position and velocity information of the particle and repeat steps (1) and (2).

[0129] (4) After the iteration, the active power reduction and output reactive power value of each photovoltaic inverter based on the fair incentive strategy are output.

[0130] It should be emphasized that the embodiments of the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation modes. Any other implementation modes derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A real-time voltage control method for a distribution network based on a fair incentive strategy, characterized in that: The following steps are involved: Step 1: Establish a comprehensive objective function for optimizing voltage regulation with minimum network loss and voltage deviation in the distribution network; Step 2: Based on the comprehensive objective function established in step 1, a variable coefficient reactive-voltage optimization control model of the photovoltaic inverter is established; Step 3: Based on the comprehensive objective function established in step 1, an active power-voltage reduction model of the photovoltaic inverter is established; Step 4: Based on the reactive power-voltage optimization control model with variable coefficient of photovoltaic inverter established in step 2 and the active power-voltage reduction model of photovoltaic inverter established in step 3, a fair incentive strategy is proposed; Step 5: According to the reactive power to be output by each photovoltaic inverter and the active power to be reduced obtained in step 4, the voltage and voltage deviation of the distribution network are calculated using the obtained electrical parameters of the distribution network, and the calculation formula and result are substituted into the objective function established in step 1; Step 6: Give the constraint conditions of the voltage regulation optimization comprehensive objective function established in step 1; Step 7: Based on the comprehensive objective function established in step 1 and the constraints given in step 6, the particle swarm algorithm is used to solve the optimal voltage fairness strategy.

2. According to claim 1, a real-time voltage control method for a distribution network based on a fair incentive strategy is characterized in that: The specific steps of step 1 include: (1) Establish a comprehensive objective function for optimizing voltage regulation with minimum network loss and voltage deviation in the distribution network. The constraint target is the distribution network loss P Loss Minimum, each node voltage deviation value U DV Minimum: In the formula, i and j represent the starting and ending nodes of the line, N represents the number of system nodes, and U i , U j Indicates the voltage at the beginning and end of the line; cosθ ij represents the node voltage phase angle cosine, g ij Indicates line conductance; U N Indicates the node voltage rating; U max , U min Indicates the maximum and minimum values ​​of node voltage; (2) Assign weights to the above two objective functions respectively and form a comprehensive objective function f: minf=α1P Loss +α2U DV (3) α1+α2＝1(4) In the formula, α1 and α2 are weight coefficients, which can be selected according to the needs of distribution network optimization.

3. The method for real-time voltage control in a distribution network based on a fair incentive strategy according to claim 1 is characterized in that: The specific method of step 2 is: The relationship between the reactive power and active power output of the photovoltaic inverter can be expressed as: Where: Q PV is the reactive power output by the photovoltaic inverter; S PV is the apparent power of the photovoltaic inverter; P PV is the active power of the photovoltaic inverter; In the traditional constant coefficient voltage-reactive power droop control VVDC mode, the reactive power target value of the photovoltaic power station is calculated according to formula (6): Q obj = Q0 + K qv (U ref - U meas )U meas <U L or U meas >U H (6) Where: Q obj is the reactive power target value of distributed photovoltaic, in per unit value; Q0 is the voltage of distributed photovoltaic grid connection point, U meas The corresponding work power is in per unit value; K qv is the reactive voltage droop control coefficient; U ref is the grid connection point voltage reference value, unit is per unit value; U H is the upper limit of the dead zone voltage; U L is the lower limit of the dead zone voltage; In the variable coefficient VVDC mode, the droop coefficient should be proportional to its reactive power capacity: Where: is the maximum reactive power that the i-th PV inverter can provide at time t; n is the number of PV inverters in the area; α is set according to the reactive power demand.

4. The method for real-time voltage control in a distribution network based on a fair incentive strategy according to claim 1 is characterized in that: The specific method of step 3 is: If the voltage U meas Lower than the upper limit of the allowable voltage U up When the photovoltaic power generation is connected to the grid according to the maximum power point tracking MPPT power; if the voltage of the grid-connected node exceeds the upper limit of the allowable voltage, the photovoltaic power generation will no longer be connected to the grid according to the MPPT power, but the photovoltaic grid-connected active power will be cut off according to the predetermined voltage-active power curve; Calculate the active power reduction amount P according to the following formula: R ; Where: β is the proportional coefficient, which can be set according to actual conditions.

5. The method for real-time voltage control in a distribution network based on a fair incentive strategy according to claim 1 is characterized in that: The specific method of step 4 is: Ensure that the ratio of reactive power to active power output of each photovoltaic inverter is consistent. The consistency of the ratio of reactive power to active power is calculated according to the following formula: In the formula, S PVi and S PVj are the apparent powers of the i-th and j-th PV inverters respectively; Q PVi and Q PVj are the reactive powers output by the i-th and j-th PV inverters respectively; and are the active power cut by the i-th and j-th PV inverters respectively; and are the maximum active powers of the i-th and j-th PV inverters respectively.

6. The method for real-time voltage control in a distribution network based on a fair incentive strategy according to claim 1 is characterized in that: The specific steps of step 5 include: (1) Obtain the electrical parameters of the distribution network, including topology, line length and unit length impedance, node load and photovoltaic capacity; (2) Establish a voltage deviation calculation model to calculate the voltage deviation before and after photovoltaic access: Now assume that the voltage of node i before connecting to distributed photovoltaic is U i0 , the voltage after connecting to distributed photovoltaic is U i1 ,but Where P and Q are the active and reactive power generated by the photovoltaic power source respectively; P L and Q L are local active and reactive loads at the grid connection point, respectively; R and X are line resistance and reactance; The second term on the right side of the equal sign in formula (10) is much smaller than the first term, so after ignoring the second term, the voltage change at the grid connection point can be approximately expressed as:

7. The method for real-time voltage control in a distribution network based on a fair incentive strategy according to claim 1 is characterized in that: The constraints of step 6 include: 1) AC power flow equation constraints Where: P Gi and Q Gi are the active power and reactive power injected by node i respectively; P Li and Q Li are the active power and reactive power of the load at node i respectively; δ ij is the phase difference between the voltage vectors at node i and node j; G ij and B ij are the conductance and susceptance of the line between node i and node j respectively; n is the total number of nodes in the power grid; 2) Voltage and current scenario constraints IN i,min ≤U i ≤U i,max (13) I i,min ≤I i ≤I i,max (14) Where: U i,max , U i,min Respectively represent the upper and lower limits of the voltage of the grid node i; I i,max ,I i,min Respectively represent the upper and lower limits of the current of the grid node i; 3) Active and reactive power constraints of photovoltaic inverters Where: Q PV,min , Q PV,max Respectively represent the minimum and maximum reactive power of the photovoltaic inverter; P PV,min , P PV,max Indicates the minimum and maximum active power of the PV inverter.

8. The method for real-time voltage control in a distribution network based on a fair incentive strategy according to claim 1 is characterized in that: The specific steps of step 7 include: (1) The population size of the voltage fairness optimal strategy is set. At the same time, the position information of the mth particle is composed of grid parameters, distributed photovoltaic parameters, and load parameters, and the particle position and speed are initialized; (2) Calculate the voltage deviation and network loss of the distribution network as the fitness value of the particle; evaluate the fitness values ​​of all particles, select the global optimal position and individual extreme point of the particle and save them separately; (3) Determine the maximum number of iterations or convergence accuracy. If the requirements of formula (1) and formula (2) are met, the process ends. If the requirements are not met, update the position and velocity information of the particle and repeat steps (1) and (2). (4) After the iteration, the active power reduction and output reactive power value of each photovoltaic inverter based on the fair incentive strategy are output.

Images