A power distribution network closing loop voltage phase angle difference coordinated regulation method and system

Abstract

The application discloses a power distribution network closing loop voltage phase angle difference cooperative regulation method and system, and belongs to the technical field of power distribution network operation and control. The application aims at the problems of large closing loop phase angle difference fluctuation, traditional control dependence on offline parameters and insufficient regulation precision under high proportion distributed photovoltaic access, constructs a power distribution network online closing loop equivalent circuit, collects electrical quantity in real time to calculate real-time phase angle difference of a closing loop bus, and online identifies main network equivalent reactance; when the phase angle difference exceeds the standard, initial adjustment amount is calculated based on the adjustment sensitivity of distributed photovoltaic, energy storage and flexible load, and cooperative regulation instructions are issued, regulation is iteratively corrected through proportional integral closed loop feedback, the phase angle difference converges to a safe range, closing loop is executed, and the operation state of regulation resources is restored after the closing loop is completed. The application can realize active regulation of the closing loop phase angle difference, effectively improves the safety of closing loop operation and the power supply reliability of the power distribution network.

Description

Technical Field

[0001] This invention belongs to the field of power distribution network operation and control technology, specifically relating to a method and system for coordinated control of the phase angle difference of the closed-loop voltage in a power distribution network based on online sensitivity identification and feedback correction. Background Technology

[0002] As the penetration rate of distributed photovoltaic (PV) power in low-voltage distribution networks continues to increase, the operation mode of distribution networks is becoming increasingly complex, and loop-closing operations are becoming more frequent. Theoretical analysis and engineering measurement data show that the widespread integration of distributed PV leads to significant time-varying fluctuations in the phase angle of the 10kV bus voltage. The bus voltage phase angle is negative during peak PV generation at noon and positive during nighttime PV shutdown, and the range of phase angle fluctuations continues to expand with the increase in distributed PV penetration. When there are differences in the proportion of distributed PV installed capacity and real-time output between the two feeders involved in the loop-closing operation, it will directly lead to a significant increase in the voltage phase angle difference of the loop-closing bus. At the same time, due to the randomness and volatility of distributed PV output itself, the loop-closing phase angle difference exhibits irregular random fluctuations throughout the day, significantly increasing the control difficulty of the loop-closing operation.

[0003] Traditional distribution network loop-closing control methods mainly rely on offline power flow calculations and the experience-based judgment of maintenance personnel. They pre-set loop-closing conditions based solely on typical operating modes, failing to adapt to the dynamic changes in bus voltage phase angle caused by real-time fluctuations in distributed photovoltaic (PV) output. This leads to errors in loop-closing condition judgment, resulting in safety accidents such as excessive loop-closing inrush current, relay protection malfunctions, and even damage to distribution equipment. Existing improved loop-closing control technologies mostly focus only on regulating the loop-closing voltage amplitude difference, lacking online assessment and active regulation capabilities for the voltage phase angle difference. Furthermore, they fail to fully explore the synergistic regulation potential of flexible low-voltage resources such as distributed PV, energy storage, and flexible loads. When the loop-closing phase angle difference exceeds the limit, they cannot achieve accurate and efficient active regulation, resulting in low loop-closing success rates, poor regulation accuracy, and insufficient power supply reliability, making it difficult to meet the safe operation requirements of distribution networks with high proportions of distributed PV access. Summary of the Invention

[0004] To address this, the present invention provides a method and system for coordinated control of voltage phase angle difference in distribution network loop, which solves the problems of low loop closing success rate, poor control accuracy, and insufficient power supply reliability guarantee capability of traditional technologies.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for coordinated control of phase angle difference in closed-loop voltage of a distribution network, comprising: S1. Construct an online loop-closing equivalent circuit for the distribution network adapted to the distributed photovoltaic access scenario, and use the online loop-closing equivalent circuit as the basic model for phase angle difference calculation and control quantity analysis; S2. Real-time acquisition of electrical operation data of the busbars at both ends of the loop to be closed, calculation of the real-time voltage phase angle difference of the busbars at both ends of the loop to be closed based on the real-time measurement data, and online identification of the equivalent operating parameters of the main grid; S3. Determine whether the real-time voltage phase angle difference exceeds the preset safety threshold. If it does, calculate the initial adjustment amount of each type of control resource based on the adjustment sensitivity characteristics of distributed photovoltaic, energy storage, and flexible load control resources, and issue a coordinated control command to the corresponding control resource. S4. After the initial adjustment is performed, the feedback correction amount is calculated based on the real-time feedback of the change in the phase angle difference of the bus voltage. The adjustment is iteratively corrected until the phase angle difference of the voltage at both ends of the loop converges to a safe range, and then the loop closing operation is performed. S5. After the loop closure operation is completed, gradually restore the original operating state of various regulatory resources.

[0006] As a preferred scheme for the coordinated control method of voltage phase angle difference in distribution network loop closing, in step S1, based on the constructed equivalent circuit of online loop closing of the distribution network, the analytical expression of the voltage phase angle difference between the 10kV busbars at both ends of the loop to be closed is derived as follows: ; In the formula, The voltage phase angle difference between the two busbars at the two ends of the loop to be closed; , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These are the equivalent electromotive forces on the main grid side of substations A and B, respectively. , These are the voltage amplitudes of the 10kV busbars at substations A and B, respectively. , These are the equivalent aggregate load active power on the A and B substation sides, respectively; , These are the equivalent aggregated distributed photovoltaic active power outputs on the A and B substation sides, respectively. , These are the equivalent aggregated energy storage discharge power on the A and B substation sides, respectively. A negative value indicates that the energy storage is in a charging state.

[0007] As a preferred scheme for the coordinated control method of voltage phase angle difference in distribution network loop closing, in step S2, the specific method for online identification of the equivalent operating parameters of the main grid is as follows: using the changes in bus voltage and outgoing current before and after a small step jump in distributed photovoltaic power, the equivalent reactance of the main grid on both sides of the loop to be closed is calculated respectively. The calculation formula is: ; ; In the formula, , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These represent the changes in the phasor voltage of the 10kV busbars of substations A and B before and after the power step. , These are the current phasors of the 10kV outgoing lines from substations A and B, respectively.

[0008] As a preferred scheme for the coordinated control method of voltage phase angle difference in distribution network, in step S2, the electrical operation data is collected using GPS / BeiDou synchronous timing technology; the collected electrical operation data includes 10kV bus voltage phasor, 10kV outgoing line current phasor, main grid side equivalent electromotive force, real-time active power output of distributed photovoltaic, real-time charging and discharging power of energy storage, and real-time power of flexible load.

[0009] As the preferred scheme for the coordinated control method of phase angle difference of closed-loop voltage in distribution networks, the analytical expressions for the adjustment sensitivity and the adjustment logic of various control resources in step S3 are as follows: (1) Distributed photovoltaic regulation sensitivity: ; ; In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the distributed photovoltaic output on sides A and B, respectively. The output level of the distributed photovoltaic is adjusted according to the positive and negative values ​​of the sensitivity. (2) Energy storage regulation sensitivity: ; ; In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the energy storage discharge power on sides A and B, respectively. The charging and discharging power of the energy storage is adjusted according to the positive and negative values ​​of the sensitivities. (3) Sensitivity of flexible load adjustment: ; ; In the formula, , These are the sensitivity of the loop voltage phase angle difference to the power of the flexible loads on sides A and B, respectively. The operating power of the flexible loads is adjusted according to the positive and negative values ​​of the sensitivity.

[0010] As a preferred scheme for the coordinated control method of voltage phase angle difference in distribution network loop, the process of calculating the initial adjustment amount of various control resources in step S3 is as follows: Calculate the phase angle difference to be adjusted: ; Calculate the total initial active power regulation requirement: ; The initial adjustment amount is allocated according to the ratio of the absolute value of the adjustment sensitivity of each type of resource to the current adjustable capacity: ; In the formula: The phase angle difference is the amount to be adjusted; This represents the current measured voltage phase angle difference; The phase angle difference of the target voltage; This represents the total initial active power regulation requirement. This is the initial adjustment coefficient; Equivalent reactance on the reference side; Let be the initial adjustment amount for the i-th type of regulatory resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; Let be the current adjustable capacity of the i-th type of controllable resource.

[0011] As a preferred scheme for the coordinated control method of voltage phase angle difference in distribution networks, in step S4, during the calculation of the feedback correction amount based on the real-time feedback of the change in bus voltage phase angle difference, a proportional-integral closed-loop control model is adopted, and the calculation formula is as follows: ; In the formula: This represents the total feedback correction amount; This is a proportionality coefficient used to control the instantaneous response speed of the correction amount; These are integral coefficients used to control the steady-state convergence accuracy of the correction amount; The residual phase angle difference after initial adjustment is denoted as , and the difference between the measured phase angle difference after initial adjustment and the target phase angle difference is denoted as .

[0012] As a preferred scheme for the coordinated control method of voltage phase angle difference in distribution network loop, the calculation formula for the redistribution of the feedback correction amount among the control resources is as follows: ; In the formula: For the single-resource feedback correction amount of the i-th type of regulated resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; The remaining adjustable capacity after the initial adjustment of the i-th type of control resource; This represents the total feedback correction amount; It is the sum of the products of the absolute values ​​of the sensitivity of all controllable resources and the remaining adjustable capacity.

[0013] As a preferred scheme for the coordinated control method of voltage phase angle difference in distribution network loop closing, the control is iteratively corrected until the voltage phase angle difference between the two buses at the two ends of the loop to be closed converges to a safe range, specifically: The feedback correction amounts of each regulated resource are added to the initial regulation amount of the corresponding resource to generate the total regulation amount of a single resource. The calculation formula is as follows: ; In the formula, Let i be the total adjustment amount of the i-th type of regulatory resource. Let be the initial adjustment amount for the i-th type of regulated resource. For the feedback correction amount of the i-th type of regulatory resource; A corrective control command containing the total control amount is issued to each control resource. After completing this round of control, the real-time voltage phase angle difference is re-acquired and the residual phase angle difference is calculated. The iterative steps of feedback correction calculation, correction reallocation, total control amount generation and command issuance are repeated until the residual phase angle difference meets the convergence condition. ; In the formula, The residual phase angle difference after the current iteration. This is the preset phase angle difference convergence accuracy.

[0014] This invention also provides a distribution network closed-loop voltage phase angle difference coordinated control system for performing the above-described distribution network closed-loop voltage phase angle difference coordinated control method, comprising: The equivalent modeling module is used to construct an online loop-closing equivalent circuit for the distribution network that is adapted to the distributed photovoltaic access scenario. The online loop-closing equivalent circuit is used as the basic model for phase angle difference calculation and control quantity analysis. The measurement and parameter identification module is used to collect electrical operation data of the busbars at both ends of the loop to be closed in real time, calculate the real-time voltage phase angle difference of the busbars at both ends of the loop to be closed based on the real-time measurement data, and identify the equivalent operating parameters of the main grid online. The initial coordinated control module is used to determine whether the real-time voltage phase angle difference exceeds a preset safety threshold. If it does, it calculates the initial adjustment amount of each type of control resource based on the adjustment sensitivity characteristics of distributed photovoltaic, energy storage, and flexible load control resources, and issues coordinated control instructions to the corresponding control resources. The correction and control module is used to calculate the feedback correction amount based on the real-time feedback of the change in the phase angle difference of the bus voltage after the initial adjustment is performed. The correction and control is iteratively adjusted until the phase angle difference of the voltage at both ends of the bus to be closed converges to a safe range, and then the loop closing operation is performed. The loop closure execution and recovery module is used to gradually restore the original operating state of various control resources after the loop closure operation is completed.

[0015] As the preferred scheme for the coordinated control system of voltage phase angle difference in distribution network loop closing, the analytical expression of the voltage phase angle difference between the 10kV busbars at both ends of the loop to be closed is derived in the equivalent modeling module based on the constructed equivalent circuit of online loop closing of the distribution network: ; In the formula, The voltage phase angle difference between the two busbars at the two ends of the loop to be closed; , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These are the equivalent electromotive forces on the main grid side of substations A and B, respectively. , These are the voltage amplitudes of the 10kV busbars at substations A and B, respectively. , These are the equivalent aggregate load active power on the A and B substation sides, respectively; , These are the equivalent aggregated distributed photovoltaic active power outputs on the A and B substation sides, respectively. , These are the equivalent aggregated energy storage discharge power on the A and B substation sides, respectively. A negative value indicates that the energy storage is in a charging state.

[0016] As the preferred solution for the distribution network closed-loop voltage phase angle difference coordinated control system, the specific method for online identification of the equivalent operating parameters of the main grid in the measurement and parameter identification module is as follows: using the changes in bus voltage and outgoing current before and after a small step jump in distributed photovoltaic power, the equivalent reactance of the main grid on both sides of the loop to be closed is calculated. The calculation formula is as follows: ; ; In the formula, , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These represent the changes in the phasor voltage of the 10kV busbars of substations A and B before and after the power step. , These are the current phasors of the 10kV outgoing lines from substations A and B, respectively.

[0017] As the preferred solution for the distribution network closed-loop voltage phase angle difference coordinated control system, the electrical operation data acquisition in the measurement and parameter identification module adopts GPS / BeiDou synchronous timing technology; the acquired electrical operation data includes 10kV bus voltage phasor, 10kV outgoing line current phasor, main grid side equivalent electromotive force, distributed photovoltaic real-time active power output, energy storage real-time charging and discharging power, and flexible load real-time power.

[0018] As the preferred scheme for the coordinated control system of voltage phase angle difference in distribution network loop, the analytical expressions for the adjustment sensitivity and the adjustment logic of various control resources in the initial coordinated control module are as follows: (1) Distributed photovoltaic regulation sensitivity: ; ; In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the distributed photovoltaic output on sides A and B, respectively. The output level of the distributed photovoltaic is adjusted according to the positive and negative values ​​of the sensitivity. (2) Energy storage regulation sensitivity: ; ; In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the energy storage discharge power on sides A and B, respectively. The charging and discharging power of the energy storage is adjusted according to the positive and negative values ​​of the sensitivities. (3) Sensitivity of flexible load adjustment: ; ; In the formula, , These are the sensitivity of the loop voltage phase angle difference to the power of the flexible loads on sides A and B, respectively. The operating power of the flexible loads is adjusted according to the positive and negative values ​​of the sensitivity.

[0019] As the preferred scheme for the coordinated control system of voltage phase angle difference in distribution network, the process of calculating the initial adjustment amount of various control resources in the initial coordinated control module is as follows: Calculate the phase angle difference to be adjusted: ; Calculate the total initial active power regulation requirement: ; The initial adjustment amount is allocated according to the ratio of the absolute value of the adjustment sensitivity of each type of resource to the current adjustable capacity: ; In the formula: The phase angle difference is the amount to be adjusted; This represents the current measured voltage phase angle difference; The phase angle difference of the target voltage; This represents the total initial active power regulation requirement. This is the initial adjustment coefficient; Equivalent reactance on the reference side; Let be the initial adjustment amount for the i-th type of regulatory resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; Let be the current adjustable capacity of the i-th type of controllable resource.

[0020] As the preferred solution for the coordinated control system of voltage phase angle difference in distribution network, the correction control module uses a proportional-integral closed-loop control model to calculate the feedback correction amount based on the real-time feedback change in bus voltage phase angle difference. The calculation formula is as follows: ; In the formula: This represents the total feedback correction amount; This is a proportionality coefficient used to control the instantaneous response speed of the correction amount; These are integral coefficients used to control the steady-state convergence accuracy of the correction amount; The residual phase angle difference after initial adjustment is denoted as , and the difference between the measured phase angle difference after initial adjustment and the target phase angle difference is denoted as .

[0021] As a preferred scheme for the coordinated control system of voltage phase angle difference in distribution network loop, the formula for calculating the redistribution of the feedback correction amount among various control resources in the correction control module is as follows: ; In the formula: For the single-resource feedback correction amount of the i-th type of regulated resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; The remaining adjustable capacity after the initial adjustment of the i-th type of control resource; This represents the total feedback correction amount; It is the sum of the products of the absolute values ​​of the sensitivity of all controllable resources and the remaining adjustable capacity.

[0022] As a preferred solution for the coordinated control system of voltage phase angle difference in distribution network loop, the correction control module iteratively corrects and controls the voltage phase angle difference between the two buses at the two ends of the loop until it converges to a safe range. Specifically: The feedback correction amounts of each regulated resource are added to the initial regulation amount of the corresponding resource to generate the total regulation amount of a single resource. The calculation formula is as follows: ; In the formula, Let i be the total adjustment amount of the i-th type of regulatory resource. Let be the initial adjustment amount for the i-th type of regulated resource. For the feedback correction amount of the i-th type of regulatory resource; A corrective control command containing the total control amount is issued to each control resource. After completing this round of control, the real-time voltage phase angle difference is re-acquired and the residual phase angle difference is calculated. The iterative steps of feedback correction calculation, correction reallocation, total control amount generation and command issuance are repeated until the residual phase angle difference meets the convergence condition. ; In the formula, The residual phase angle difference after the current iteration. This is the preset phase angle difference convergence accuracy.

[0023] The present invention has the following advantages: First, this invention enables online identification of main grid operating parameters, solving the problems of traditional closed-loop control relying on offline fixed parameters and having poor adaptability. This invention utilizes measured data of distributed photovoltaic power fluctuations to identify the real-time value of the main grid's equivalent reactance online, providing a dynamic parameter basis for sensitivity calculation and adjustment allocation. This effectively avoids control errors caused by deviations between offline parameters and actual operating states, and adapts to the dynamic operating characteristics of distribution networks with high proportions of distributed photovoltaic access.

[0024] Second, this invention achieves quantitative allocation of the initial adjustment amount in closed-loop regulation, replacing the traditional empirical and extensive adjustment. Based on the derived analytical expressions of the adjustment sensitivity of various regulatory resources, this invention optimizes the allocation of the initial adjustment amount by combining the real-time adjustable capacity of each resource, significantly improving regulation efficiency and accuracy, reducing the number of ineffective adjustments, and achieving rational and efficient utilization of regulatory resources.

[0025] Third, this invention achieves closed-loop convergence control of the phase angle difference, solving the problems of insufficient accuracy and weak anti-interference capability of open-loop control. After initial adjustment, based on the residual phase angle difference feedback in real time, this invention uses a closed-loop control model to calculate the feedback correction amount. Through multiple rounds of iterative correction, the phase angle difference is stably converged to a preset safe range, effectively offsetting the influence of model errors and external disturbances, significantly reducing the risk of excessive closing-loop inrush current, and ensuring the safety and reliability of closing-loop operation.

[0026] Fourth, this invention achieves coordinated regulation of multiple flexible resources across the power grid, energy storage, and power generation systems, expanding the resource boundaries of loop-loop regulation. This invention fully integrates three types of low-voltage-side regulation resources: distributed photovoltaic power, energy storage, and flexible loads. By comprehensively considering the regulation characteristics and capabilities of each resource, it achieves coordinated and optimized regulation of multiple resources, avoiding the problems of excessive pressure and insufficient regulation capacity of a single resource. This improves the phase angle difference regulation capability and the success rate of loop-loop operation under complex operating scenarios.

[0027] Fifth, this invention is effectively adapted to distribution network operation scenarios with a high proportion of distributed photovoltaic (PV) grid integration, and has significant engineering application value. This invention solves the industry pain points of random exceeding of loop-closed phase angle differences and high control difficulty caused by distributed PV output fluctuations, effectively improving the reliability and security of uninterrupted power transfer in the distribution network, while also enhancing the distribution network's capacity to absorb distributed PV, delaying investment costs for distribution network upgrades and renovations, and combining safety and economic benefits. Attached Figure Description

[0028] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0029] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0030] Figure 1 This is a schematic diagram of the collaborative control method for the phase angle difference of the closed-loop voltage in the distribution network provided in this embodiment of the invention; Figure 2 The diagram shows the equivalent circuit model of the distribution network loop closing in the distribution network closed-loop voltage phase angle difference collaborative control method provided in the embodiments of the present invention. Figure 3 This is a schematic diagram of a simulation system for the collaborative control method of distribution network loop voltage phase angle difference provided in an embodiment of the present invention; Figure 4 This is a diagram illustrating the convergence effect of closed-loop regulation in a large-scale photovoltaic power generation scenario provided in this embodiment of the invention. Figure 5 This is a diagram illustrating the convergence effect of closed-loop control under heavy load scenarios provided in this embodiment of the invention. Figure 6 This is a comparison chart of resource regulation under two scenarios provided in this embodiment of the invention; Figure 7 This is a schematic diagram of the distribution network closed-loop voltage phase angle difference collaborative control system architecture provided in an embodiment of the present invention. Detailed Implementation

[0031] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1 See Figure 1 and Figure 2This invention provides a method for coordinated control of phase angle difference in closed-loop voltage in a distribution network, comprising: S1. Construct an online loop-closing equivalent circuit for the distribution network adapted to the distributed photovoltaic access scenario, and use the online loop-closing equivalent circuit as the basic model for phase angle difference calculation and control quantity analysis; S2. Real-time acquisition of electrical operation data of the busbars at both ends of the loop to be closed, calculation of the real-time voltage phase angle difference of the busbars at both ends of the loop to be closed based on the real-time measurement data, and online identification of the equivalent operating parameters of the main grid; S3. Determine whether the real-time voltage phase angle difference exceeds the preset safety threshold. If it does, calculate the initial adjustment amount of each type of control resource based on the adjustment sensitivity characteristics of distributed photovoltaic, energy storage, and flexible load control resources, and issue a coordinated control command to the corresponding control resource. S4. After the initial adjustment is performed, the feedback correction amount is calculated based on the real-time feedback of the change in the phase angle difference of the bus voltage. The adjustment is iteratively corrected until the phase angle difference of the voltage at both ends of the loop converges to a safe range, and then the loop closing operation is performed. S5. After the loop closure operation is completed, gradually restore the original operating state of various regulatory resources.

[0033] In this embodiment, in step S1, based on the constructed equivalent circuit of the online loop closing of the distribution network, the analytical expression of the voltage phase angle difference between the 10kV busbars at both ends of the loop to be closed is derived as follows: ; In the formula, The voltage phase angle difference between the two busbars at the two ends of the loop to be closed; , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These are the equivalent electromotive forces on the main grid side of substations A and B, respectively. , These are the voltage amplitudes of the 10kV busbars at substations A and B, respectively. , These are the equivalent aggregate load active power on the A and B substation sides, respectively; , These are the equivalent aggregated distributed photovoltaic active power outputs on the A and B substation sides, respectively. , These are the equivalent aggregated energy storage discharge power on the A and B substation sides, respectively. A negative value indicates that the energy storage is in a charging state.

[0034] Specifically, the analytical expression for the phase angle difference is derived based on equivalent circuit modeling and linearization. The complete modeling and derivation process is as follows: Construct a three-level equivalent circuit model including two 10kV busbars (A and B) of the substations to be closed, as well as their upstream and downstream components: (1) Equivalent part of upstream main grid: The main grid side of substation A is composed of equivalent electromotive force With equivalent impedance Series connection means that the main grid side of substation B is supplied with equivalent electromotive force. With equivalent impedance The series connection indicates the power supply characteristics of the main grid system to the 10kV busbars on both sides. (2) 10kV substation section: The voltage amplitude of the 10kV busbar of substation A is Voltage phase angle is The voltage amplitude of the 10kV busbar at substation B is Voltage phase angle is The two busbars are connected by a loop switch to ensure uninterrupted power supply to the load. (3) Equivalent portion of downstream distribution network: Equivalent aggregated distributed photovoltaic power output is configured on the A substation side. Equivalent aggregate load active power Equivalent aggregated energy storage discharge power The equivalent impedance of the photovoltaic grid connection path is The equivalent aggregated source-grid-load-storage parameters and line impedance are configured on the B substation side.

[0035] To achieve linearization of the nonlinear power flow equations while ensuring engineering practicality, the following basic assumptions are proposed: (1) Assumption of phase co-current of main grid power supply: The equivalent electromotive forces on the main grid sides of the two substations are in phase, satisfying the following conditions. ; (2) Active power loss neglect assumption: neglect the active power loss of the distribution network access path, and assume that the power balance at the 10kV bus is dominated by the reactance; (3) Small phase angle assumption: The phase angle difference between the two ends of the line is small, satisfying , ; (4) Ignore resistance assumption: Ignore the influence of line resistance on phase angle characteristics, and assume that the voltage phase angle is determined by the coupling relationship between reactance and active power.

[0036] Taking substation A as an example, based on the above assumptions, the active power balance equation after neglecting active power losses is: ; Based on the small phase angle assumption Substituting into the above equation, we get: ; The voltage phase angle expression for the 10kV busbar of substation A is obtained by refining the expression: ; Similarly, the voltage phase angle expression for the 10kV busbar of substation B is derived: ; The phase angle difference of the closed-loop voltage is the difference in phase angles between the two busbars, i.e. Substituting the phase angle expressions on both sides yields the analytical expression for the phase angle difference. This formula clarifies the linear mapping relationship between the closed-loop phase angle difference and the active power of the source-grid-load-storage system on both sides, providing the theoretical basis for sensitivity calculation and control quantity allocation.

[0037] In this embodiment, the specific method for online identification of the equivalent operating parameters of the main grid in step S2 is as follows: using the changes in bus voltage and outgoing current before and after a small step change in distributed photovoltaic power, the equivalent reactance of the main grid on both sides of the loop to be closed is calculated. The calculation formula is as follows: ; ; In the formula, , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These represent the changes in the phasor voltage of the 10kV busbars of substations A and B before and after the power step. , These are the current phasors of the 10kV outgoing lines from substations A and B, respectively.

[0038] Specifically, the equivalent reactance of the main grid is a parameter used for sensitivity calculation and control quantity allocation. Traditional methods use offline fixed parameters, which are prone to deviation from the actual operating conditions. This method achieves dynamic updating of parameters through online identification. The identification principle and implementation details are as follows: Based on Kirchhoff's voltage law for equivalent circuits, the voltage balance relationship of the main grid on side A is as follows: ; Due to the equivalent electromotive force of the main grid This can be considered a constant value. When the distributed photovoltaic power experiences a small step change, the change in the equivalent electromotive force of the main grid is 0. Therefore, by taking the change in the voltage balance equation, we can obtain: ; By simplification, we can obtain the identification formula for the equivalent reactance of the main grid on side A. Similarly, we can derive the identification formula for side B.

[0039] Among them, the natural fluctuations in distributed photovoltaic output are utilized, or a small step increase of 5% to 10% of the rated power is triggered by scheduling commands. No additional testing equipment is required, and the normal operation of the distribution network is not affected. Identification is performed before the loop closing operation to ensure that the parameters are completely matched with the current operating status. There is no need to know the main grid topology and parameters in advance. Reactance identification can be achieved based solely on local measurement data, which can adapt to the changes in main grid characteristics under different operating modes.

[0040] In this embodiment, in step S2, the electrical operation data is collected using GPS / BeiDou synchronous timing technology; the collected electrical operation data includes 10kV bus voltage phasor, 10kV outgoing line current phasor, main grid side equivalent electromotive force, distributed photovoltaic real-time active power output, energy storage real-time charging and discharging power, and flexible load real-time power.

[0041] Specifically, GPS / BeiDou synchronization technology is used to ensure that the time synchronization accuracy of the measurement data on both sides of the loop closure is better than 1 microsecond. Since the loop closure phase angle difference is the difference in the phase angles of the two busbars, if the measurement data on both sides are not synchronized, it will introduce a significant phase angle measurement error, which will directly affect the accuracy of the loop closure condition judgment and control. Therefore, microsecond-level synchronization is a basic hardware requirement of this method.

[0042] The functions of each data collection point are as follows: 10kV bus voltage phasor: used to directly calculate the real-time closed-loop voltage phase angle difference, and also used for online identification of the equivalent reactance of the main grid; 10kV outgoing line current phasor: used for online identification of the equivalent reactance of the main grid; Equivalent electromotive force on the main grid side: used for theoretical calculation and model verification of phase angle difference; Real-time power of distributed photovoltaic, energy storage, and flexible loads: used for theoretical calculation of phase angle difference, calculation of regulation sensitivity, and allocation and verification of regulation quantities.

[0043] The theoretical phase angle difference is calculated based on the collected power data, and compared with the measured phase angle difference to achieve model verification and error correction.

[0044] In this embodiment, the analytical expressions for the adjustment sensitivity and the adjustment logic of various control resources in step S3 are as follows: (1) Distributed photovoltaic regulation sensitivity: ; ; In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the distributed photovoltaic output on sides A and B, respectively. The output level of the distributed photovoltaic is adjusted according to the positive and negative values ​​of the sensitivity.

[0045] The negative photovoltaic sensitivity on side A indicates that for every 1MW increase in photovoltaic output on side A, the absolute value of the decrease in the loop-closed phase angle difference corresponds to a decrease in the sensitivity value. Therefore, when the loop-closed phase angle difference is positive and exceeds the standard, the distributed photovoltaic output on side A needs to be increased; when the loop-closed phase angle difference is negative and exceeds the standard, the distributed photovoltaic output on side A needs to be decreased. A positive sensitivity for photovoltaic (PV) output on side B indicates that for every 1MW increase in PV output on side B, the corresponding sensitivity value increases with the increase in the loop-closed phase angle difference. Therefore, when the loop-closed phase angle difference is positive and exceeds the standard, the distributed PV output on side B needs to be reduced; when the loop-closed phase angle difference is negative and exceeds the standard, the distributed PV output on side B needs to be increased.

[0046] (2) Energy storage regulation sensitivity: ; ; In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the energy storage discharge power on sides A and B, respectively. The charging and discharging power of the energy storage is adjusted according to the positive and negative values ​​of the sensitivities. The negative sensitivity of the A-side energy storage indicates that for every 1MW increase in the A-side energy storage discharge power, the absolute value of the decrease in the closed-loop phase angle difference corresponds to a decrease in the sensitivity value. Therefore, when the closed-loop phase angle difference is positive and exceeds the standard, the A-side energy storage discharge power needs to be increased (or the charging power needs to be decreased); when the closed-loop phase angle difference is negative and exceeds the standard, the A-side energy storage discharge power needs to be decreased (or the charging power needs to be increased). A positive sensitivity for energy storage on side B indicates that for every 1MW increase in the energy storage discharge power on side B, the corresponding sensitivity value increases with the increase in the closed-loop phase angle difference. Therefore, when the closed-loop phase angle difference is positive and exceeds the standard, the energy storage discharge power on side B needs to be reduced (or the charging power increased); when the closed-loop phase angle difference is negative and exceeds the standard, the energy storage discharge power on side B needs to be increased (or the charging power decreased).

[0047] (3) Sensitivity of flexible load adjustment: ; ; In the formula, , These are the sensitivity of the loop voltage phase angle difference to the power of the flexible loads on sides A and B, respectively. The operating power of the flexible loads is adjusted according to the positive and negative values ​​of the sensitivity.

[0048] A positive load sensitivity on side A indicates that for every 1MW increase in load power on side A, the corresponding sensitivity value increases with the loop phase angle difference. Therefore, when the loop phase angle difference is positive and exceeds the limit, the flexible load power on side A needs to be reduced; when the loop phase angle difference is negative and exceeds the limit, the flexible load power on side A needs to be increased. A negative load sensitivity on side B indicates that for every 1MW increase in load power on side B, the absolute value of the decrease in the closed-loop phase angle difference corresponds to a decrease in the sensitivity value. Therefore, when the closed-loop phase angle difference is positive and exceeds the standard, the flexible load power on side B needs to be increased; when the closed-loop phase angle difference is negative and exceeds the standard, the flexible load power on side B needs to be reduced.

[0049] The larger the absolute value of sensitivity, the higher the phase difference control efficiency of the resource. When allocating the adjustment amount, it should be given priority to resources with high sensitivity and large adjustable capacity to maximize the control efficiency.

[0050] In this embodiment, the process of calculating the initial adjustment amount of various control resources in step S3 is as follows: Calculate the phase angle difference to be adjusted: ; Calculate the total initial active power regulation requirement: ; The initial adjustment amount is allocated according to the ratio of the absolute value of the adjustment sensitivity of each type of resource to the current adjustable capacity: ; In the formula: The phase angle difference is the amount to be adjusted; This represents the current measured voltage phase angle difference; The phase angle difference of the target voltage; This represents the total initial active power regulation requirement. This is the initial adjustment coefficient; Equivalent reactance on the reference side; Let be the initial adjustment amount for the i-th type of regulatory resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; Let be the current adjustable capacity of the i-th type of controllable resource.

[0051] Specifically, the total phase angle deviation that needs to be controlled and the target phase angle deviation should be clearly defined. The initial adjustment coefficient is typically set to 0°, but can also be set to a safety value not exceeding 5° based on closed-loop safety requirements. The phase angle difference deviation is converted into total active power regulation demand, where the initial regulation coefficient... The value is typically 0.8~1.0, used to prevent initial over-adjustment and to reserve adjustment margin for feedback correction; reference side equivalent reactance. The average or larger value of the equivalent reactance of the main grid on both sides of the loop to be closed is used to ensure the conservatism of the regulation amount. A sensitivity-adjustable capacity weighted allocation method is adopted, with the weight being the product of the absolute value of the regulation sensitivity of each resource and the current adjustable capacity. This ensures both regulation efficiency (more resources with high sensitivity are allocated) and regulation feasibility (more resources with large adjustable capacity are allocated), avoiding saturation of a single resource. The initial regulation command includes the device number, regulation direction, initial regulation amount, and regulation start and end times. The command transmission status is monitored in real time. If some devices cannot receive the command, the system automatically switches to inter-device communication to ensure command delivery.

[0052] In this embodiment, in step S4, during the calculation of the feedback correction amount based on the real-time feedback bus voltage phase angle difference change, a proportional-integral closed-loop control model is used, and the calculation formula is as follows: ; In the formula: This represents the total feedback correction amount; This is a proportionality coefficient used to control the instantaneous response speed of the correction amount; These are integral coefficients used to control the steady-state convergence accuracy of the correction amount; The residual phase angle difference after initial adjustment is denoted as , and the difference between the measured phase angle difference after initial adjustment and the target phase angle difference is denoted as .

[0053] Specifically, due to factors such as model errors, photovoltaic power output fluctuations, and adjustment execution deviations, there is usually a residual phase angle difference after the initial adjustment. Therefore, proportional-integral closed-loop control is used to correct this difference. The control logic is as follows: An instantaneous correction is generated based on the current residual phase angle difference, and the scaling factor is used. A larger value results in a faster correction response, but excessively large values ​​can easily cause adjustment oscillations. Integrating the historical residual phase angle difference eliminates steady-state errors; the integral coefficient... The larger the value, the faster the steady-state convergence speed. This invention has the characteristics of fast response and zero steady-state error convergence, which can effectively offset the influence of model error and external disturbance, and converge the phase angle difference to the target range.

[0054] In this embodiment, the formula for calculating the redistribution of the feedback correction amount among the various control resources is as follows: ; In the formula: For the single-resource feedback correction amount of the i-th type of regulated resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; The remaining adjustable capacity after the initial adjustment of the i-th type of control resource; This represents the total feedback correction amount; This is the sum of the absolute values ​​of the sensitivity of all resources eligible for regulation and the remaining adjustable capacity. Weighted allocation is performed using the remaining adjustable capacity after initial regulation, rather than the initial adjustable capacity, to avoid resources that have reached their regulation limits continuing to undertake regulation tasks, ensuring the feasibility of corrective regulation. The reallocation still follows the principles of sensitivity priority and capacity matching to ensure the efficiency and reliability of corrective regulation.

[0055] In this embodiment, the voltage phase angle difference between the two busbars at both ends of the loop to be closed converges to a safe range through iterative correction and control. Specifically: The feedback correction amounts of each regulated resource are added to the initial regulation amount of the corresponding resource to generate the total regulation amount of a single resource. The calculation formula is as follows: ; In the formula, Let i be the total adjustment amount of the i-th type of regulatory resource. Let be the initial adjustment amount for the i-th type of regulated resource. For the feedback correction amount of the i-th type of regulatory resource; A corrective control command containing the total control amount is issued to each control resource. After completing this round of control, the real-time voltage phase angle difference is re-acquired and the residual phase angle difference is calculated. The iterative steps of feedback correction calculation, correction reallocation, total control amount generation and command issuance are repeated until the residual phase angle difference meets the convergence condition. ; In the formula, The residual phase angle difference after the current iteration. This is the preset phase angle difference convergence accuracy.

[0056] Specifically, each iteration sequentially executes phase angle difference acquisition, residual phase angle difference calculation, total feedback correction calculation, correction reallocation, total adjustment generation, and correction command issuance. The interval between each iteration is typically set to 1-2 seconds to match the adjustment response speed of source-grid-load-storage resources. Phase angle difference convergence accuracy... The value is set to 1°~2° to ensure that the inrush current of the closed loop is within a safe range; after the phase angle difference meets the convergence accuracy, it needs to remain stable for more than 5 seconds to avoid the situation where the phase angle difference meets the standard instantaneously but fluctuates too much, thus ensuring the safety of the closed loop; after the convergence condition is met, the closed loop decision unit issues a closing command to execute the closed loop operation; during the closed loop, the closed loop current, active power, voltage and frequency changes are monitored in real time, the closed loop process data is completely recorded and sent back to the control center for post-event analysis and strategy optimization.

[0057] To verify the parameter identification accuracy, sensitivity calculation accuracy, control convergence performance, and extreme scenario adaptability of the proposed distribution network closed-loop voltage phase angle difference coordinated control method, a simulation system for a distribution network with a high proportion of distributed photovoltaic power was built, conforming to engineering practice and covering two extreme typical operating scenarios of the distribution network. The effectiveness of the method was verified from multiple dimensions, as detailed below:

[0058] I. Simulation System Architecture and Basic Parameter Settings

[0059] This simulation constructed a typical urban power distribution network topology with three voltage levels: 220kV, 110kV, and 10kV, matching the engineering application scenario of the method of this invention. The simulation system topology is as follows: Figure 3 As shown, the overall architecture is as follows: The 220kV busbar B0_2 is connected to the 110kV common busbar B0_1 via the main transformer T0; the 110kV common busbar is connected to the high-voltage side busbars B1_2 and B2_2 of the two 110kV substations via lines L1 and L2 respectively; the two 110kV substations are stepped down to the 10kV busbars B1_1 (busbar to be closed in loop on side A) and B2_1 (busbar to be closed in loop on side B) via the main transformers T1 and T2 respectively; the two 10kV busbars are the objects of the loop closing operation, and the busbar sides are respectively connected to three types of controllable resources: distributed photovoltaic, flexible load, and energy storage.

[0060] Busbar parameter settings are shown in Table 1: Table 1 Busbar Parameter Table

[0061] See Tables 2 and 3 for transformer and line parameter settings: Table 2 Transformer Equipment Parameters

[0062] Table 3 Line Equipment Parameters

[0063] The transformer and line parameters all adopt typical engineering parameters of domestic power distribution networks to reproduce the impedance characteristics of real power distribution networks.

[0064] Transformer parameters: including 220kV / 110kV main transformer T0 and two 110kV / 10kV distribution transformers T1 and T2. The parameters match the resistance and reactance ratio of the actual distribution transformers, accurately reflecting the transformer's influence on voltage phase angle. Line parameters: The impedance parameters of 110kV interconnection lines L1 and L2 are matched with the electrical characteristics of the actual overhead lines to accurately reflect the contribution of line impedance to the phase angle difference.

[0065] II. Simulation Scene Setup This simulation selects two extreme typical operating scenarios of high-proportion distributed photovoltaic (PV) grid integration, covering the extreme operating conditions of PV output, to verify the control capability of the method under the most stringent conditions. The initial energy storage power in both scenarios is set to 0 to eliminate interference from the initial energy storage output. The simulation scenario settings are shown in Table 4. Table 4 Simulation Scene Parameters

[0066] Among them, heavy load scenarios: Operating conditions: The distributed photovoltaic output on both sides A and B is 0, simulating the operating state of complete photovoltaic shutdown at night; the active power of the load on side A is 100MW and the active power of the load on side B is 20MW, with a significant difference in load levels between the two sides; Scenario significance: This scenario simulates a traditional heavy-load operation with significant differences in load characteristics on both sides of the loop and no photovoltaic power output support. (See also...) Figure 4 In this scenario, the initial closed-loop phase angle difference is -13.27°, which far exceeds the closed-loop safety threshold of ±5°. This is a typical operating condition in which the traditional closed-loop control method is prone to excessive inrush current.

[0067] Large-scale photovoltaic application scenarios: Operating conditions: Distributed photovoltaic power output of 300MW on side A and 100MW on side B, simulating a high penetration rate operating state with full photovoltaic power generation at noon; the load on both sides is consistent with the heavy load scenario; Scenario Significance: This scenario simulates a novel operating scenario where a high proportion of photovoltaic (PV) power is connected to the grid, and there is a significant difference in PV output on both sides of the loop. (See also: [link to relevant documentation]) Figure 5 In this scenario, the initial loop closing phase angle difference is 14.38°, which also far exceeds the loop closing safety threshold. This is a new type of pain point scenario for loop closing in power distribution networks that this invention focuses on solving.

[0068] III. Verification of Online Identification Results of Equivalent Reactance of Main Network This section verifies the accuracy of the online identification method for the equivalent reactance of the main grid based on small-amplitude photovoltaic power fluctuations proposed in this invention. This is the parameter basis for sensitivity calculation and control quantity allocation. Identification process: In the simulation, a small step of 10% rated power is triggered in the distributed photovoltaic power on both sides. The phasors of 10kV bus voltage and outgoing current are collected before and after the step. The equivalent reactance of the main grid is calculated according to the identification formula proposed in this invention. Identification results: The equivalent reactance of the main grid on side A is 0.406Ω, and the equivalent reactance of the main grid on side B is 0.388Ω; see Table 5 for details. Table 5. Main Network Equivalent Parameter Results

[0069] Results show that the deviation between the identification results and the actual equivalent reactance of the main network in the simulation system is less than 5%, proving that the online identification method of the present invention does not need to rely on the main network topology and offline parameters, and can obtain the real-time operating parameters of the main network based solely on local measurement data. This solves the problem that traditional closed-loop control uses offline fixed parameters and has a large deviation from the actual operating state.

[0070] IV. Verification of the accuracy of sensitivity calculation This section verifies the accuracy of the analytical expression for the sensitivity of resource regulation derived in this invention: Verification method: The theoretical sensitivity calculated based on the analytical formula of this invention is compared with the actual sensitivity (i.e., the actual change in the closed loop phase angle difference caused by unit active power regulation) obtained based on the accurate power flow calculation of the simulation system, and the identification error is calculated.

[0071] Results analysis: The control direction is 100% accurate: the positive and negative signs of the theoretical sensitivity and actual sensitivity of all control resources are completely consistent, proving that the sensitivity adjustment logic derived in this invention is completely correct, and avoiding the safety risk of incorrect control direction in principle; The error is within the acceptable range for engineering: See Table 6. The identification error of various resources is between 24.2% and 36.5%. This error comes from the linearization assumption of the equivalent circuit, which is an acceptable error in engineering applications. Moreover, this error can be completely eliminated by the feedback closed-loop correction link of the present invention, without affecting the final control convergence accuracy. Table 6 Results of Main Network Equivalent Parameters

[0072] Theoretical derivation consistency verification: The absolute values ​​of the sensitivity of distributed photovoltaic, energy storage and flexible load on the same side are completely consistent, which is consistent with the analytical derivation conclusion of the phase angle difference of this invention: The degree of influence of the change of active power on the closed loop phase angle difference on the same bus side is consistent, and only the adjustment direction changes with different resource types, which verifies the correctness of the theoretical model.

[0073] V. Verification of Convergence Performance

[0074] This section is the simulation verification stage, which verifies the convergence speed, convergence accuracy, and multi-resource collaborative control effect of the "initial adjustment and feedback closed-loop correction" control architecture of the present invention. The simulation is set with a target closed-loop phase angle difference of 0°, a closed-loop safety threshold of ±5°, and a convergence accuracy of ±0.05°.

[0075] See Figure 4 The effects of regulation on large-scale photovoltaic power generation scenarios are as follows: Initial state: The phase angle difference between the closed loop and the closed loop is 14.38°, which is far beyond the ±5° safety boundary and does not meet the closed loop condition; Control process: After one initial adjustment and one feedback correction, and only 1.2 iterations, the phase angle difference quickly converged from 14.38° to -0.02°, which was completely within the convergence accuracy range and stabilized in the target region; Results: The method demonstrates fast control speed and high precision, far exceeding the 1°~2° convergence accuracy required by engineering projects, proving its excellent control performance in scenarios with high proportion of photovoltaic grid connection.

[0076] See Figure 5 The control effect in heavy-load scenarios is as follows: Initial state: The phase angle difference between the closed loops is -13.27°, which is also far beyond the safety boundary; Control process: After one initial adjustment and one feedback correction, and only 1.2 iterations, the phase angle difference quickly converged from -13.27° to 0.03°, meeting the convergence accuracy requirements; Results: Fast convergence with zero steady-state error was achieved in both extreme scenarios, proving that the method has strong adaptability to different operating scenarios and solves the problems of traditional loop control failure and low loop closure success rate under extreme conditions.

[0077] See Figure 6 The effects of multi-resource coordinated regulation are as follows: The adjustment direction conforms to the sensitivity logic of this invention, and no adjustment direction error occurs; the adjustment amount is allocated according to the weighted principle of the absolute value of sensitivity and the remaining adjustable capacity, realizing the coordinated control of three types of resources: distributed photovoltaic, energy storage, and flexible load. This avoids the problem of excessive adjustment pressure and adjustment saturation of a single resource, and fully realizes the design goal of coordinated control of source, grid, load and storage of this invention.

[0078] VI. Simulation Conclusions This simulation verified the effectiveness of the proposed method from three dimensions: parameter identification, sensitivity accuracy, and control performance. The online identification accuracy of the equivalent reactance of the main grid is high, providing a reliable parameter basis for control. The sensitivity analytical expression accurately controls the direction. In two extreme typical scenarios, it can quickly and accurately converge the closed-loop phase angle difference far exceeding the safety threshold to the target value. The control efficiency and accuracy are far superior to traditional methods, demonstrating excellent engineering practicality and scenario adaptability. It can effectively solve the industry pain point of excessive closed-loop phase angle difference in distribution networks under high-proportion distributed photovoltaic access.

[0079] Example 2 See Figure 7 Embodiment 2 of the present invention also provides a distribution network closed-loop voltage phase angle difference coordinated control system for performing the distribution network closed-loop voltage phase angle difference coordinated control method of the above embodiments, including: The equivalent modeling module 100 is used to construct an online loop-closing equivalent circuit of the distribution network adapted to the distributed photovoltaic access scenario, and the online loop-closing equivalent circuit is used as the basic model for phase angle difference calculation and control quantity analysis. The measurement and parameter identification module 200 is used to collect electrical operation data of the busbars at both ends of the loop to be closed in real time, calculate the real-time voltage phase angle difference of the busbars at both ends of the loop to be closed based on the real-time measurement data, and identify the equivalent operating parameters of the main grid online. The initial coordinated control module 300 is used to determine whether the real-time voltage phase angle difference exceeds a preset safety threshold. If it does, it calculates the initial adjustment amount of each type of control resource based on the adjustment sensitivity characteristics of distributed photovoltaic, energy storage, and flexible load control resources, and issues a coordinated control command to the corresponding control resource. The correction and control module 400 is used to calculate the feedback correction amount based on the real-time feedback of the change in the phase angle difference of the bus voltage after the initial adjustment is performed. The correction and control is iteratively adjusted until the phase angle difference of the voltage at both ends of the bus to be closed converges to a safe range, and then the loop closing operation is performed. The loop closure execution and recovery module 500 is used to gradually restore the original operating state of various control resources after the loop closure operation is completed.

[0080] In this embodiment, in the equivalent modeling module 100, based on the constructed online loop-closing equivalent circuit of the distribution network, the analytical expression for the voltage phase angle difference between the 10kV busbars at both ends of the loop to be closed is derived as follows:

[0081] In the formula, The voltage phase angle difference between the two busbars at the two ends of the loop to be closed; , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These are the equivalent electromotive forces on the main grid side of substations A and B, respectively. , These are the voltage amplitudes of the 10kV busbars at substations A and B, respectively. , These are the equivalent aggregate load active power on the A and B substation sides, respectively; , These are the equivalent aggregated distributed photovoltaic active power outputs on the A and B substation sides, respectively. , These are the equivalent aggregated energy storage discharge power on the A and B substation sides, respectively. A negative value indicates that the energy storage is in a charging state.

[0082] In this embodiment, the measurement and parameter identification module 200 identifies the equivalent operating parameters of the main grid online in the following way: using the changes in bus voltage and outgoing current before and after a small step change in distributed photovoltaic power, the equivalent reactance of the main grid on both sides of the loop to be closed is calculated. The calculation formula is as follows: ; ; In the formula, , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These represent the changes in the phasor voltage of the 10kV busbars of substations A and B before and after the power step. , These are the current phasors of the 10kV outgoing lines from substations A and B, respectively.

[0083] In this embodiment, the electrical operation data acquisition in the measurement and parameter identification module 200 adopts GPS / BeiDou synchronous timing technology; the acquired electrical operation data includes 10kV bus voltage phasor, 10kV outgoing line current phasor, main grid side equivalent electromotive force, distributed photovoltaic real-time active power output, energy storage real-time charging and discharging power, and flexible load real-time power.

[0084] In this embodiment, the analytical expressions for the adjustment sensitivity and the adjustment logic of various control resources in the initial coordinated control module 300 are as follows: (1) Distributed photovoltaic regulation sensitivity: ; ; In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the distributed photovoltaic output on sides A and B, respectively. The output level of the distributed photovoltaic is adjusted according to the positive and negative values ​​of the sensitivity. (2) Energy storage regulation sensitivity: ; ; In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the energy storage discharge power on sides A and B, respectively. The charging and discharging power of the energy storage is adjusted according to the positive and negative values ​​of the sensitivities. (3) Sensitivity of flexible load adjustment: ; ; In the formula, , These are the sensitivity of the loop voltage phase angle difference to the power of the flexible loads on sides A and B, respectively. The operating power of the flexible loads is adjusted according to the positive and negative values ​​of the sensitivity.

[0085] In this embodiment, the initial adjustment amount of various control resources is calculated in the initial coordinated control module 300 as follows: Calculate the phase angle difference to be adjusted: ; Calculate the total initial active power regulation requirement: ; The initial adjustment amount is allocated according to the ratio of the absolute value of the adjustment sensitivity of each type of resource to the current adjustable capacity: ; In the formula: The phase angle difference is the amount to be adjusted; This represents the current measured voltage phase angle difference; The phase angle difference of the target voltage; This represents the total initial active power regulation requirement. This is the initial adjustment coefficient; Equivalent reactance on the reference side; Let be the initial adjustment amount for the i-th type of regulatory resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; Let be the current adjustable capacity of the i-th type of controllable resource.

[0086] In this embodiment, the correction and control module 400 uses a proportional-integral closed-loop control model to calculate the feedback correction amount based on the real-time feedback change in the bus voltage phase angle difference. The calculation formula is as follows: ; In the formula: This represents the total feedback correction amount; This is a proportionality coefficient used to control the instantaneous response speed of the correction amount; These are integral coefficients used to control the steady-state convergence accuracy of the correction amount; The residual phase angle difference after initial adjustment is denoted as , and the difference between the measured phase angle difference after initial adjustment and the target phase angle difference is denoted as .

[0087] In this embodiment, the formula for calculating the redistribution of the feedback correction amount among the control resources in the correction and control module 400 is as follows: ; In the formula: For the single-resource feedback correction amount of the i-th type of regulated resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; The remaining adjustable capacity after the initial adjustment of the i-th type of control resource; This represents the total feedback correction amount; It is the sum of the products of the absolute values ​​of the sensitivity of all controllable resources and the remaining adjustable capacity.

[0088] In this embodiment, the correction and control module 400 iteratively corrects and controls the voltage phase angle difference between the two busbars at the two ends of the loop to be closed until it converges to a safe range. Specifically: The feedback correction amounts of each regulated resource are added to the initial regulation amount of the corresponding resource to generate the total regulation amount of a single resource. The calculation formula is as follows: ; In the formula, Let i be the total adjustment amount of the i-th type of regulatory resource. Let be the initial adjustment amount for the i-th type of regulated resource. For the feedback correction amount of the i-th type of regulatory resource; A corrective control command containing the total control amount is issued to each control resource. After completing this round of control, the real-time voltage phase angle difference is re-acquired and the residual phase angle difference is calculated. The iterative steps of feedback correction calculation, correction reallocation, total control amount generation and command issuance are repeated until the residual phase angle difference meets the convergence condition. ; In the formula, The residual phase angle difference after the current iteration. This is the preset phase angle difference convergence accuracy.

[0089] It should be noted that the information interaction and execution process between the modules of the above system are based on the same concept as the method embodiment in Embodiment 1 of this application, and the resulting technical effects are the same as those in the method embodiment of this application. For details, please refer to the description in the method embodiment shown above in this application, and it will not be repeated here.

[0090] Example 3 Embodiment 3 of the present invention provides a non-transitory computer-readable storage medium, wherein the computer-readable storage medium stores program code for a method of coordinated control of the phase angle difference of the closed-loop voltage of a distribution network, the program code including instructions for executing the method of coordinated control of the phase angle difference of the closed-loop voltage of a distribution network as described in Embodiment 1 or any possible implementation thereof.

[0091] Computer-readable storage media can be any available medium that a computer can access, or a data storage device such as a server or data center that integrates one or more available media. The available medium can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives (SSDs)).

[0092] Example 4 Embodiment 4 of the present invention provides an electronic device, including: a memory and a processor; The processor and the memory communicate with each other via a bus; the memory stores program instructions that can be executed by the processor, and the processor can call the program instructions to execute the distribution network closed-loop voltage phase angle difference coordinated control method of Embodiment 1 or any possible implementation thereof.

[0093] Specifically, a processor can be implemented in hardware or software. When implemented in hardware, the processor can be a logic circuit, an integrated circuit, etc. When implemented in software, the processor can be a general-purpose processor that reads software code stored in memory. This memory can be integrated into the processor or located outside the processor and exist independently.

[0094] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means.

[0095] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0096] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for coordinated control of phase angle difference in closed-loop voltage in a distribution network, characterized in that, include: S1. Construct an online loop-closing equivalent circuit for the distribution network adapted to the distributed photovoltaic access scenario, and use the online loop-closing equivalent circuit as the basic model for phase angle difference calculation and control quantity analysis; S2. Real-time acquisition of electrical operation data of the busbars at both ends of the loop to be closed, calculation of the real-time voltage phase angle difference of the busbars at both ends of the loop to be closed based on the real-time measurement data, and online identification of the equivalent operating parameters of the main grid; S3. Determine whether the real-time voltage phase angle difference exceeds the preset safety threshold. If it does, calculate the initial adjustment amount of each type of control resource based on the adjustment sensitivity characteristics of distributed photovoltaic, energy storage, and flexible load control resources, and issue a coordinated control command to the corresponding control resource. S4. After the initial adjustment is performed, the feedback correction amount is calculated based on the real-time feedback of the change in the phase angle difference of the bus voltage. The adjustment is iteratively corrected until the phase angle difference of the voltage at both ends of the loop converges to a safe range, and then the loop closing operation is performed. S5. After the loop closure operation is completed, gradually restore the original operating state of various regulatory resources.

2. The method for coordinated control of phase angle difference in closed-loop voltage of distribution network according to claim 1, characterized in that, In step S1, based on the constructed equivalent circuit of the online loop closing of the distribution network, the analytical expression for the voltage phase angle difference between the 10kV busbars at both ends of the loop to be closed is derived as follows: ； In the formula, The voltage phase angle difference between the two busbars at the two ends of the loop to be closed; , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These are the equivalent electromotive forces on the main grid side of substations A and B, respectively. , These are the voltage amplitudes of the 10kV busbars at substations A and B, respectively. , These are the equivalent aggregate load active power on the A and B substation sides, respectively; , These are the equivalent aggregated distributed photovoltaic active power outputs on the A and B substation sides, respectively. , These are the equivalent aggregated energy storage discharge power on the A and B substation sides, respectively. A negative value indicates that the energy storage is in a charging state.

3. The method for coordinated control of phase angle difference in closed-loop voltage of distribution network according to claim 2, characterized in that, In step S2, the specific method for online identification of the equivalent operating parameters of the main grid is as follows: using the changes in bus voltage and outgoing current before and after a small step change in distributed photovoltaic power, the equivalent reactance of the main grid on both sides of the loop to be closed is calculated. The calculation formula is: ； ； In the formula, , These are the equivalent reactances of the main grid on the A and B substation sides, respectively. , These represent the changes in the phasor voltage of the 10kV busbars of substations A and B before and after the power step. , These are the current phasors of the 10kV outgoing lines from substations A and B, respectively.

4. The method for coordinated control of phase angle difference in closed-loop voltage of distribution network according to claim 3, characterized in that, In step S2, the electrical operation data is collected using GPS / BeiDou synchronous timing technology. The collected electrical operation data includes 10kV bus voltage phasor, 10kV outgoing line current phasor, main grid side equivalent electromotive force, real-time active power output of distributed photovoltaic, real-time charging and discharging power of energy storage, and real-time power of flexible load.

5. The method for coordinated control of phase angle difference in closed-loop voltage of distribution network according to claim 3, characterized in that, In step S3, the analytical expressions for the regulation sensitivity and regulation logic of various regulatory resources are as follows: (1) Distributed photovoltaic regulation sensitivity: ； ； In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the distributed photovoltaic output on sides A and B, respectively. The output level of the distributed photovoltaic is adjusted according to the positive and negative values ​​of the sensitivity. (2) Energy storage regulation sensitivity: ； ； In the formula, , These are the sensitivities of the phase angle difference of the closed-loop voltage to the energy storage discharge power on sides A and B, respectively. The charging and discharging power of the energy storage is adjusted according to the positive and negative values ​​of the sensitivities. (3) Sensitivity of flexible load adjustment: ； ； In the formula, , These are the sensitivity of the loop voltage phase angle difference to the power of the flexible loads on sides A and B, respectively. The operating power of the flexible loads is adjusted according to the positive and negative values ​​of the sensitivity.

6. The method for coordinated control of phase angle difference in closed-loop voltage of distribution network according to claim 5, characterized in that, In step S3, the process of calculating the initial adjustment amount of various regulatory resources is as follows: Calculate the phase angle difference to be adjusted: ； Calculate the total initial active power regulation requirement: ； The initial adjustment amount is allocated according to the ratio of the absolute value of the adjustment sensitivity of each type of resource to the current adjustable capacity: ； In the formula: The phase angle difference is the amount to be adjusted; This represents the current measured voltage phase angle difference; The phase angle difference of the target voltage; This represents the total initial active power regulation requirement. This is the initial adjustment coefficient; Equivalent reactance on the reference side; Let be the initial adjustment amount for the i-th type of regulatory resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; Let be the current adjustable capacity of the i-th type of controllable resource.

7. The method for coordinated control of phase angle difference in closed-loop voltage of distribution network according to claim 6, characterized in that, In step S4, during the calculation of the feedback correction amount based on the real-time feedback of the bus voltage phase angle difference change, a proportional-integral closed-loop control model is used, and the calculation formula is as follows: ； In the formula: This represents the total feedback correction amount; This is a proportionality coefficient used to control the instantaneous response speed of the correction amount; These are integral coefficients used to control the steady-state convergence accuracy of the correction amount; The residual phase angle difference after initial adjustment is denoted as , and the difference between the measured phase angle difference after initial adjustment and the target phase angle difference is denoted as .

8. The method for coordinated control of phase angle difference in closed-loop voltage of distribution network according to claim 7, characterized in that, The formula for calculating the redistribution of the feedback correction amount among the various control resources is as follows: ； In the formula: For the single-resource feedback correction amount of the i-th type of regulated resource; Let be the absolute value of the regulatory sensitivity of the i-th type of regulatory resource; The remaining adjustable capacity after the initial adjustment of the i-th type of control resource; This represents the total feedback correction amount; It is the sum of the products of the absolute values ​​of the sensitivity of all controllable resources and the remaining adjustable capacity.

9. The method for coordinated control of phase angle difference in closed-loop voltage of distribution network according to claim 8, characterized in that, The voltage phase angle difference between the two busbars at both ends of the loop to be closed is adjusted and controlled iteratively until it converges to a safe range. Specifically: The feedback correction amounts of each regulated resource are added to the initial regulation amount of the corresponding resource to generate the total regulation amount of a single resource. The calculation formula is as follows: ； In the formula, Let i be the total adjustment amount of the i-th type of regulatory resource. Let be the initial adjustment amount for the i-th type of regulated resource. For the feedback correction amount of the i-th type of regulatory resource; A corrective control command containing the total control amount is issued to each control resource. After completing this round of control, the real-time voltage phase angle difference is re-acquired and the residual phase angle difference is calculated. The iterative steps of feedback correction calculation, correction reallocation, total control amount generation and command issuance are repeated until the residual phase angle difference meets the convergence condition. ； In the formula, The residual phase angle difference after the current iteration. This is the preset phase angle difference convergence accuracy.

10. A distribution network closed-loop voltage phase angle difference coordinated control system, used to execute the distribution network closed-loop voltage phase angle difference coordinated control method according to any one of claims 1-9, characterized in that, include: The equivalent modeling module is used to construct an online loop-closing equivalent circuit for the distribution network that is adapted to the distributed photovoltaic access scenario. The online loop-closing equivalent circuit is used as the basic model for phase angle difference calculation and control quantity analysis. The measurement and parameter identification module is used to collect electrical operation data of the busbars at both ends of the loop to be closed in real time, calculate the real-time voltage phase angle difference of the busbars at both ends of the loop to be closed based on the real-time measurement data, and identify the equivalent operating parameters of the main grid online. The initial coordinated control module is used to determine whether the real-time voltage phase angle difference exceeds a preset safety threshold. If it does, it calculates the initial adjustment amount of each type of control resource based on the adjustment sensitivity characteristics of distributed photovoltaic, energy storage, and flexible load control resources, and issues coordinated control instructions to the corresponding control resources. The correction and control module is used to calculate the feedback correction amount based on the real-time feedback of the change in the phase angle difference of the bus voltage after the initial adjustment is performed. The correction and control is iteratively adjusted until the phase angle difference of the voltage at both ends of the bus to be closed converges to a safe range, and then the loop closing operation is performed. The loop closure execution and recovery module is used to gradually restore the original operating state of various control resources after the loop closure operation is completed.

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