Zone area photovoltaic balanced absorption control method and system based on energy storage

Abstract

The invention discloses a zone area photovoltaic equalization consumption control method and system based on energy storage, and relates to the technical field of photovoltaic equalization consumption, and the method comprises the steps: generating a topological fingerprint vector between a capacitor cabinet grounding point and an open triangle PT grounding point; generating a ground potential gradient vector according to the topological fingerprint vector and the residual voltage drainage current of the capacitor cabinet, and measuring the initial output voltage of the open-delta PT; according to the ground potential gradient vector, measuring a post-anchoring output voltage of the open triangle PT, and generating a post-anchoring potential lifting vector; and according to the initial output voltage, the output voltage after anchoring, the ground potential gradient vector and the potential lifting vector after anchoring, calculating a bias mapping constant corresponding to the common ground drainage effect in the target area. According to the invention, the photovoltaic localization utilization rate of the transformer area can be improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic equalization and absorption technology, and in particular to a control method and system for equalization and absorption of photovoltaic power in distribution areas based on energy storage. Background Technology

[0002] With the large-scale integration of distributed photovoltaic (PV) power, distribution networks at the transformer substation level are exhibiting new operational characteristics such as dual fluctuations in source and load, frequent power backflow, and deteriorating voltage quality. Particularly in scenarios with multiple PV points connected, such as rural and suburban transformer substations, there is a significant time misalignment between PV output and user load, leading to low local absorption rates, severe curtailment, and exacerbated reverse power flow disturbances. Furthermore, transformer substations are often equipped with energy storage systems for energy regulation and power balancing; however, existing energy storage control strategies often fail to adequately consider dynamic changes in voltage state and potential differences between multiple nodes, resulting in delayed energy storage response and an inability to effectively support power quality in the transformer substation. Especially when multiple energy storage devices or equipment share a common grounding, some nodes experience potential shifts and voltage distortion, further impacting the operational safety of the transformer substation and the efficiency of PV power generation.

[0003] In existing technologies, the regulation of photovoltaic (PV) output fluctuations in distribution areas generally relies on fixed empirical parameters or centralized dispatch, lacking the ability to dynamically adjust based on actual voltage conditions. This leads to dispatch lag or over-response, making it difficult to adapt to the real-time energy balance requirements of the distribution area. Especially in actual operation, because the energy storage system cannot accurately identify the power gap and voltage deviation between the current PV and load, its charging, discharging, and reactive power regulation actions become disconnected from the actual operating state of the distribution area, thus failing to achieve a high proportion of local PV absorption. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies that rely on fixed empirical parameters or centralized scheduling when regulating the fluctuations in photovoltaic output in distribution areas, lacking the ability to dynamically adjust based on actual voltage conditions, resulting in scheduling lag or over-response. Therefore, this invention proposes a photovoltaic equalization and absorption control method and system based on energy storage.

[0005] To address the problems existing in the prior art, the present invention adopts the following technical solution:

[0006] A photovoltaic power grid equalization and absorption control method based on energy storage includes:

[0007] S1. Generate the topological fingerprint vector between the capacitor bank grounding point and the open delta PT grounding point;

[0008] S2. Based on the topological fingerprint vector and the residual voltage current of the capacitor bank, generate the ground potential gradient vector and measure the initial output voltage of the open delta PT.

[0009] S3. Measure the anchored output voltage of the open delta PT based on the ground potential gradient vector, and generate the anchored potential rise vector.

[0010] S4. Calculate the bias mapping constant corresponding to the common ground diversion effect in the target transformer area based on the initial output voltage, the output voltage after anchoring, the ground potential gradient vector, and the potential rise vector after anchoring.

[0011] S5. Based on the ground potential gradient vector and the bias mapping constant, calculate the net residual voltage of the open delta PT.

[0012] S6. Determine the active power of the energy storage system based on the energy balance difference of the target transformer area, and determine the reactive power of the energy storage system based on the net residual voltage.

[0013] S7. Dynamically balance and control the photovoltaic absorption status of the target area based on active power and reactive power.

[0014] Preferably, generating a topological fingerprint vector between the capacitor bank grounding point and the open delta PT grounding point includes:

[0015] The first equivalent grounding resistance is obtained by measuring the resistance of the first grounding path between the capacitor bank grounding point and the open delta PT grounding point using the four-terminal method.

[0016] The second equivalent grounding resistance is obtained by measuring the resistance of the second grounding path between the capacitor bank grounding point and the open delta PT grounding point using the four-terminal method.

[0017] The third equivalent grounding resistance is obtained by measuring the resistance of the third grounding path between the capacitor bank grounding point and the open delta PT grounding point using the four-terminal method.

[0018] The first equivalent grounding resistance, the second equivalent grounding resistance, and the third equivalent grounding resistance are combined into a topological fingerprint vector.

[0019] Preferably, the ground potential gradient vector is generated based on the topological fingerprint vector and the residual voltage diversion current of the capacitor bank, including:

[0020] Read the residual voltage value of the capacitors in the capacitor bank;

[0021] Read the nominal resistance value of the discharge resistor in the capacitor bank;

[0022] Divide the residual voltage value by the nominal resistance value to obtain the residual voltage current.

[0023] Multiply the first equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain the initial first potential rise value;

[0024] Multiply the second equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain the initial second potential boost value;

[0025] Multiply the third equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain the initial third potential rise value;

[0026] The initial first potential rise value, the initial second potential rise value, and the initial third potential rise value are combined to obtain the ground potential gradient vector.

[0027] Preferably, the anchored output voltage of the open-delta PT is measured based on the ground potential gradient vector, and the anchored potential rise vector is generated, including:

[0028] Connect the high-resistance isolation branch to the first grounding path via a relay;

[0029] Calculate the GA-GB relative potential difference between the initial first potential rise value and the initial second potential rise value in the ground potential gradient vector;

[0030] Calculate the GA-GC relative potential difference between the initial first potential rise value and the initial third potential rise value in the ground potential gradient vector;

[0031] Adjust the resistance of the high-resistance isolation branch until the relative potential difference between GA-GB and GA-GC drops to within the resolution range of the instrument measuring equipment;

[0032] After the resistance adjustment process of the high-resistance isolation branch is completed, measure the first potential rise value after anchoring of the first grounding path, the second potential rise value after anchoring of the second grounding path, and the third potential rise value after anchoring of the third grounding path, and measure the output voltage of the open delta PT after anchoring.

[0033] The first potential boost value, the second potential boost value, and the third potential boost value after anchoring are combined to form the anchoring potential boost vector.

[0034] Preferably, based on the initial output voltage, the output voltage after anchoring, the ground potential gradient vector, and the potential rise vector after anchoring, the bias mapping constant corresponding to the common ground diversion effect in the target transformer area is calculated, including:

[0035] The difference between the initial output voltage and the anchored output voltage is calculated to obtain the output voltage difference.

[0036] Calculate the total potential change based on the ground potential gradient vector and the potential rise vector after anchoring;

[0037] The bias mapping constant is obtained by calculating the ratio between the output voltage difference and the total potential change.

[0038] Preferably, the net residual voltage of the open-delta PT is calculated based on the ground potential gradient vector and the bias mapping constant, including:

[0039] The initial first potential rise value, the initial second potential rise value, and the initial third potential rise value in the ground potential gradient vector are summed to obtain the total potential rise.

[0040] The bias voltage of the open delta PT is obtained by multiplying the sum of potential increases with the bias mapping constant.

[0041] The net residual voltage of the open delta PT is obtained by calculating the difference between the current measured output voltage and the bias voltage.

[0042] Preferably, the active power of the energy storage system is determined based on the energy balance difference of the target transformer area, and the reactive power of the energy storage system is determined based on the net residual voltage, including:

[0043] The difference between the total power generation of all photovoltaic inverters in the target area and the load power of the target area is calculated to obtain the energy balance difference of the area.

[0044] The active power of the energy storage system is determined based on the energy balance difference of the transformer area, the minimum allowable active power and the maximum allowable active power of the energy storage system in the target transformer area.

[0045] Calculate the reactive power control quantity of the energy storage system based on the net residual voltage and the voltage-reactive power response slope of the target area.

[0046] The reactive power of the energy storage system is determined based on the reactive power control quantity, the lower limit of reactive power of the energy storage system, and the upper limit of reactive power.

[0047] Preferably, dynamic equilibrium control is performed on the photovoltaic absorption status of the target distribution area based on active power and reactive power, including:

[0048] Collect real-time photovoltaic power output and real-time user load power of the target area;

[0049] The charging and discharging of the energy storage system in the target area is scheduled based on the difference between real-time photovoltaic power output and real-time user load power, and the active power.

[0050] Collect real-time grid node voltages for the target transformer area;

[0051] Obtain the rated voltage of the power grid nodes in the target distribution area;

[0052] The reactive power compensation scheduling of the energy storage system is carried out based on the deviation between the real-time grid node voltage and the rated voltage, and the reactive power.

[0053] To address the aforementioned problems, this invention also provides a photovoltaic power distribution system based on energy storage, the system comprising:

[0054] The topology identification module is used to generate a topology fingerprint vector between the capacitor bank grounding point and the open delta PT grounding point;

[0055] The ground potential modeling module is used to generate a ground potential gradient vector based on the topological fingerprint vector and the residual voltage current of the capacitor bank, and to measure the initial output voltage of the open delta PT.

[0056] The equipotential anchoring module is used to measure the anchored output voltage of the open delta PT based on the ground potential gradient vector, and to generate the anchored potential rise vector.

[0057] The bias calculation module is used to calculate the bias mapping constant corresponding to the common ground diversion effect in the target transformer area based on the initial output voltage, the output voltage after anchoring, the ground potential gradient vector, and the potential rise vector after anchoring.

[0058] The net residual voltage calculation module is used to calculate the net residual voltage of an open-delta PT based on the ground potential gradient vector and the bias mapping constant.

[0059] The energy storage power scheduling module is used to determine the active power of the energy storage system based on the energy balance difference of the target transformer area, and to determine the reactive power of the energy storage system based on the net residual voltage.

[0060] The photovoltaic equalization control module is used to dynamically equalize the photovoltaic absorption status of the target area based on active power and reactive power.

[0061] Compared with the prior art, the beneficial effects of the present invention are:

[0062] 1. In this invention, by constructing a dynamic energy dispatching mechanism at the distribution substation level, the energy storage system collects photovoltaic output and user load power in real time, accurately calculates the energy balance difference of the distribution substation, and dispatches the active power of the energy storage system for charging and discharging operations accordingly. This effectively solves the problem in traditional distribution substations where photovoltaic output exceeds local load and cannot be absorbed locally, requiring backfeeding to the upper-level grid. Based on real-time physical quantities, it enables rapid response, improves the local utilization rate of photovoltaic power in the distribution substation, achieves source-load adaptive adjustment, and enhances the level of new energy consumption.

[0063] 2. In this invention, the reactive power regulation capability of the energy storage system is combined with the introduction of the net residual voltage index as a voltage deviation characterization signal. Combined with the response slope parameter calibrated by the first-order trial injection method, a reactive power regulation logic based on proportional control for the energy storage system is constructed. This overcomes the problems of reactive power regulation being limited by fixed thresholds, response lag, and inconsistent regulation directions in the prior art. It enables the energy storage system to flexibly output reactive power according to the actual voltage state, and realizes real-time, accurate, and continuous dynamic correction of node voltage under bias elimination conditions, thereby effectively ensuring the voltage quality and operational stability of the distribution area.

[0064] 3. In this invention, by introducing an equipotential anchoring and bias mapping calculation mechanism, the systematic voltage deviation caused by the current diversion effect between grounding systems is actively identified and suppressed, forming a net residual voltage calculation model. By incorporating the anchoring state and scheduling instructions into a unified control logic, a complete closed-loop control path including topology identification, potential modeling, residual voltage correction, and power output is constructed. This ensures the physical accuracy of the control basis and the consistency of the execution results, enabling the energy storage control behavior to have anti-bias capability and maintain precise control effect under complex transformer substation grounding structures, thereby improving the universality and robustness of the entire control system. Attached Figure Description

[0065] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0066] Figure 1 This is a flowchart illustrating a photovoltaic power distribution balance control method based on energy storage according to an embodiment of the present invention.

[0067] Figure 2 This is a functional block diagram of a photovoltaic equalization and absorption control system based on energy storage provided in an embodiment of the present invention. Detailed Implementation

[0068] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0069] Example: This example provides a method for balanced grid integration control of photovoltaic power distribution areas based on energy storage. See [link to example]. Figure 1 Specifically, including:

[0070] S1. Generate the topological fingerprint vector between the capacitor bank grounding point and the open delta PT grounding point;

[0071] In an embodiment of the present invention, generating a topological fingerprint vector between the capacitor bank grounding point and the open delta PT grounding point includes:

[0072] The first equivalent grounding resistance is obtained by measuring the resistance of the first grounding path between the capacitor bank grounding point and the open delta PT grounding point using the four-terminal method.

[0073] Specifically, the capacitor bank grounding point indicates the location where the capacitor compensation device forms an electrical connection with the ground. It is the potential terminal where the system's reactive power compensation device discharges residual current and establishes a zero-sequence reference. The first grounding path indicates the conductive path between the capacitor bank grounding point and the open delta PT grounding point. The conductivity of this path determines the distribution characteristics of the ground potential difference between the two points. The four-terminal resistance measurement is used to accurately measure the resistance of the grounding path through independent current sources and voltage sampling terminals to eliminate additional errors from the conductors and contact parts. The first equivalent grounding resistance characterizes the overall impedance characteristics of the grounding path for current conduction and is a key parameter reflecting the electrical integrity of the grounding structure and the balance of the grounding grid.

[0074] Specifically, an open delta PT represents a voltage detection unit formed by connecting the secondary windings of three-phase voltage transformers in an open delta configuration. Its main function is to monitor changes in the zero-sequence voltage of the system and reflect the grounding status of the transformer substation. This structure typically consists of the secondary windings of three-phase transformers connected end to end, with the two ends of one phase winding left open to form a non-closed delta connection. When the three-phase voltages of the system are balanced, the voltage at the open end is close to zero. When a single-phase ground fault or voltage imbalance occurs in the system, a voltage output proportional to the zero-sequence component will appear at the open end. The open delta PT can achieve sensitive detection of neutral point offset, voltage imbalance, and grounding faults in the transformer substation, providing an accurate reference voltage signal for voltage correction and bias calculation of the energy storage system.

[0075] Specifically, when performing four-terminal resistance measurement on the first grounding path between the capacitor bank grounding point and the open delta PT grounding point, a current injection electrode and a voltage sampling electrode are first arranged at both ends of the grounding path to ensure sufficient spacing between the current electrode and the voltage electrode to reduce the influence of electrode contact resistance on the measurement results. Then, a stable test current is applied to the current electrode through a constant current source, allowing the current to flow along the first grounding path. Next, a high-precision voltage measurement device is used to collect the potential difference signal across the voltage sampling electrode. Then, the ratio between the measured voltage value and the applied current value is calculated to obtain the resistance value of the path. Finally, the measurement data is temperature corrected and repeatedly verified to eliminate the influence of environmental factors and contact deviations, thereby obtaining the first equivalent grounding resistance of the first grounding path, providing accurate basic data for the subsequent construction of the topology fingerprint vector.

[0076] The second equivalent grounding resistance is obtained by measuring the resistance of the second grounding path between the capacitor bank grounding point and the open delta PT grounding point using the four-terminal method.

[0077] Specifically, the second grounding path is used to represent another electrical conduction path between the capacitor bank grounding point and the open delta PT grounding point, in addition to the first grounding path. This path is usually formed through different grounding leads or grounding bodies, and its conductivity reflects the multi-point coupling characteristics of the grounding system. The second equivalent grounding resistance is used to characterize the comprehensive impedance characteristics of the second grounding path during current conduction. Its value reflects the electrical connectivity and grounding quality of the path and is an important parameter for evaluating the balance of potential distribution in the transformer substation area.

[0078] Specifically, when performing four-terminal resistance measurement on the second grounding path between the capacitor bank grounding point and the open delta PT grounding point, firstly, current injection electrodes and voltage sampling electrodes are respectively arranged at both ends of the second grounding path to keep the measurement channel independent from the first grounding path and avoid current coupling interference. Then, a stable test current with a known amplitude is applied to the current electrode using a constant current source, allowing the current to flow independently along the second grounding path. Subsequently, the corresponding potential difference signal is collected at both ends of the voltage electrode using a high-precision voltage sampling device. Then, the resistance value is calculated based on the measured voltage value and the applied current value to obtain the preliminary measurement result of the path. Afterwards, the measured data is repeatedly compared and corrected for temperature drift to eliminate errors caused by poor electrode contact or external stray currents. Finally, the corrected second equivalent grounding resistance is obtained to reflect the conductivity and grounding integrity of the path, providing reliable parameter support for forming the topological fingerprint vector of the grounding network.

[0079] The third equivalent grounding resistance is obtained by measuring the resistance of the third grounding path between the capacitor bank grounding point and the open delta PT grounding point using the four-terminal method.

[0080] Specifically, the third grounding path is used to represent another electrical connection path between the capacitor bank grounding point and the open delta PT grounding point, in addition to the first and second grounding paths. This path is usually formed by an independent grounding lead or an auxiliary grounding body, and is used to reflect the current distribution characteristics of the remaining channels in a multi-point grounding system. The third equivalent grounding resistance is used to characterize the comprehensive impedance characteristics of the third grounding path for current conduction, and its value reflects the conductivity and ground potential coupling degree of the path.

[0081] Specifically, when performing a four-terminal resistance measurement on the third grounding path between the capacitor bank grounding point and the open delta PT grounding point, firstly, current injection electrodes and voltage sampling electrodes are respectively arranged at both ends of the third grounding path to ensure that the current loop is isolated from the first two paths to prevent crosstalk of the test signals; then, a stable DC test current is applied to the current injection electrodes through a constant current source, so that the current forms a closed loop along the third grounding path; next, a high-sensitivity voltage acquisition device is used to record the potential difference between the voltage sampling electrodes; the resistance value of the path is calculated based on the measured voltage value and the known current value; then, the measurement results are corrected for ambient temperature and averaged multiple times to eliminate measurement errors and improve the stability of the results; finally, the corrected third equivalent grounding resistance is obtained, and this resistance value is used to characterize the electrical connectivity performance and ground potential balance of the third grounding path.

[0082] Specifically, the first, second, and third grounding paths represent three independent electrical conduction paths between the capacitor bank grounding point and the open delta PT grounding point, respectively. They differ in structural connection, current distribution, and grounding performance. The first grounding path is usually the main grounding loop, directly formed by the capacitor bank's main grounding wire and the busbar grounding wire, serving as the system's primary discharge channel. The second grounding path is generally formed by auxiliary grounding leads or parallel grounding bodies, with a longer electrical distance and slightly higher resistance, used for auxiliary discharge and redundant protection. The third grounding path is often an additional channel formed by equipment casing protective grounding, measuring ground, or other branch grounding structures; its conductivity is significantly affected by the surrounding soil resistivity and installation location. By performing resistance measurements and potential distribution analysis on each of the three paths, the conductivity characteristics of each path and its contribution to ground current shunting can be distinguished, thereby accurately describing the overall electrical characteristics and ground potential distribution patterns of the multi-point grounding system in the transformer substation.

[0083] The first equivalent grounding resistance, the second equivalent grounding resistance, and the third equivalent grounding resistance are combined into a topological fingerprint vector.

[0084] Specifically, the first, second, and third equivalent grounding resistances are used to characterize the conductivity and impedance characteristics of the three independent grounding paths between the capacitor bank grounding point and the open delta PT grounding point. Each equivalent grounding resistance reflects the grounding quality and ground potential distribution of the corresponding path. The three are combined to form a topological fingerprint vector, which is used to comprehensively describe the electrical topological structure characteristics of the transformer substation grounding system. This vector can reflect the relative relationship between each grounding path and the balance of the overall grounding network, providing basic parameters for subsequent ground potential gradient calculation and bias analysis.

[0085] In general, generating a topological fingerprint vector between the capacitor bank grounding point and the open-delta PT grounding point is to accurately characterize the equivalent grounding resistance distribution characteristics of the three grounding paths between them. This vector serves as a key quantitative basis for the electrical integrity of the grounding topology and the balance of the ground grid. It can provide basic data support for the subsequent generation of the ground potential gradient vector and the implementation of equipotential anchoring operations, thereby eliminating the interference of uneven grounding path impedance on the ground potential, ensuring the accuracy of the open-delta PT voltage measurement, and ultimately ensuring the accuracy of reactive power dispatch and the reliability of dynamic balance control of photovoltaic consumption status in the photovoltaic consumption process based on energy storage.

[0086] S2. Based on the topological fingerprint vector and the residual voltage current of the capacitor bank, generate the ground potential gradient vector and measure the initial output voltage of the open delta PT.

[0087] In an embodiment of the present invention, a ground potential gradient vector is generated based on the topological fingerprint vector and the residual voltage dredging current of the capacitor bank, including:

[0088] Read the residual voltage value of the capacitors in the capacitor bank;

[0089] Read the nominal resistance value of the discharge resistor in the capacitor bank;

[0090] Divide the residual voltage value by the nominal resistance value to obtain the residual voltage current.

[0091] Specifically, the residual voltage value of the capacitor in the capacitor bank represents the potential difference that still exists across the capacitor after the capacitor compensation device has been taken out of operation or de-energized, due to incomplete discharge of charge. This voltage reflects the state of incomplete dissipation of energy stored in the capacitor. The nominal resistance value of the discharge resistor in the capacitor bank represents the rated resistance value of the discharge element connected in parallel across the capacitor under design conditions. Its function is to provide a stable discharge path for the capacitor to ensure safe voltage recovery. The residual voltage current represents the current flow formed by the release of residual charge from the capacitor under the action of the discharge resistor. Its magnitude depends on the residual voltage across the capacitor and the discharge resistor value. This current reflects the degree of continued influence of the capacitor on the ground potential after it has been taken out of operation.

[0092] Specifically, dividing the residual voltage of the capacitor in the capacitor bank by the nominal resistance of the discharge resistor to obtain the residual voltage current is based on Ohm's law relationship between current, voltage, and resistance. That is, in a steady-state conductive circuit, the current flowing through a resistor is directly proportional to the voltage across it and inversely proportional to the resistance value. When the capacitor energy storage element is disconnected, its internal residual charge is released through the parallel discharge resistor. This discharge process forms a current channel, and the magnitude of the instantaneous current depends on the residual voltage across the capacitor and the resistance value of the discharge resistor. Therefore, by dividing the residual voltage by the discharge resistor, the actual current in the circuit can be obtained. This current directly reflects the rate and duration of energy release by the capacitor and is an important basic parameter for analyzing ground potential changes and the influence of common ground bias.

[0093] Multiply the first equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain the initial first potential rise value;

[0094] Multiply the second equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain the initial second potential boost value;

[0095] Multiply the third equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain the initial third potential rise value;

[0096] Specifically, the initial first potential rise value represents the magnitude of the ground potential increase generated by the first grounding path under the action of the residual voltage dredging current. Its magnitude reflects the degree of local potential rise after the path conducts the ground current. The initial second potential rise value represents the magnitude of the ground potential change generated when the residual voltage dredging current flows through the second grounding path. Its value reflects the conductivity and ground potential response characteristics of the path. The initial third potential rise value represents the amount of ground potential rise formed when the residual voltage dredging current acts on the third grounding path. Its magnitude characterizes the grounding impedance characteristics and energy coupling capability of the path. Together, these three values ​​reflect the influence of different channels on the distribution of residual current in a multi-point grounding system, providing basic data for constructing the ground potential gradient vector and analyzing the degree of potential imbalance.

[0097] Specifically, multiplying the equivalent grounding resistance in the topological fingerprint vector by the residual voltage current to obtain the initial potential rise value is based on the linear relationship between voltage, current, and resistance in Ohm's law. When the residual voltage current flows through different grounding paths, the voltage rise of each path is equal to the product of the equivalent grounding resistance of that path and the current flowing through it. Since the equivalent resistances of the three grounding paths are different, the potential rise generated by the same residual voltage current on each path is also different. Therefore, calculating the product of the three paths separately yields the initial first potential rise value, the initial second potential rise value, and the initial third potential rise value. These potential rise values ​​directly reflect the response characteristics of each grounding path to the ground potential distribution under the action of the residual voltage current, providing a basis for the subsequent construction of the ground potential gradient vector and potential bias compensation.

[0098] The initial first potential rise value, the initial second potential rise value, and the initial third potential rise value are combined to obtain the ground potential gradient vector.

[0099] Specifically, the ground potential gradient vector is used to represent the ground potential distribution characteristics formed by multiple grounding paths. It is a multi-dimensional potential characterization quantity obtained by combining the initial first potential rise value, the initial second potential rise value, and the initial third potential rise value. This vector reflects the potential difference and spatial variation trend formed by different grounding channels under the action of residual voltage dredging current. Each component corresponds to the potential rise degree of different grounding paths, and the overall vector direction and amplitude can describe the direction of ground potential change and gradient intensity. By constructing the ground potential gradient vector, the potential imbalance state of the transformer substation grounding system can be quantitatively characterized, providing basic data support for subsequent potential anchoring, bias correction, and voltage measurement accuracy optimization.

[0100] Specifically, when measuring the initial output voltage of an open-delta PT, the secondary side of the voltage transformer is first connected to the voltage measurement circuit in an open-delta configuration, ensuring that the three-phase windings are connected end-to-end and that one open terminal is reserved as the voltage output terminal. Then, under stable system operation and without external interference, a high-precision voltage sampling device is connected to the open terminal to collect the output voltage signal of the open-delta PT in real time. Next, the sampled signal is filtered and steady-state determined to remove transient interference components and high-frequency noise, ensuring the stability and accuracy of the measurement data. Subsequently, the steady-state voltage value at this moment is recorded as the initial output voltage, and this data is stored in the control unit for subsequent difference analysis with the anchored output voltage. Through this step, the voltage reference value of the open-delta PT before potential anchoring can be accurately obtained, providing a reliable reference for subsequent bias mapping calculation and net residual voltage solution.

[0101] S3. Measure the anchored output voltage of the open delta PT based on the ground potential gradient vector, and generate the anchored potential rise vector.

[0102] In an embodiment of the present invention, the anchored output voltage of the open delta potential transformer (PT) is measured based on the ground potential gradient vector, and an anchored potential rise vector is generated, including:

[0103] Connect the high-resistance isolation branch to the first grounding path via a relay;

[0104] Specifically, a high-impedance isolation branch is used to represent a high-impedance electrical connection channel set between the capacitor bank grounding system and the open delta PT grounding system. Its main function is to achieve weak coupling adjustment of ground potential while maintaining electrical isolation. This branch is usually composed of high-resistance resistor elements or composite impedance components. By limiting the current flowing between the two grounding systems, it ensures that the electrical systems on both sides do not interfere with each other under DC and low-frequency conditions. At the same time, it can form a weak discharge channel when there is a potential shift. When the system performs potential anchoring operation, the high-impedance isolation branch, as a controllable potential balance path, achieves slow adjustment of ground potential through relay connection or disconnection, so that the grounding network reaches a potential balance state, thereby eliminating the bias voltage generated by the common ground current diversion effect and ensuring the stability and accuracy of the open delta PT output voltage.

[0105] Specifically, when connecting the high-resistance isolation branch to the first grounding path via a relay, a high-resistance isolation branch is first laid between the capacitor bank grounding system and the open delta PT grounding system, with one end connected to the capacitor bank grounding point and the other end connected to the conductive terminal of the first grounding path. Then, a controllable relay is connected in series at the connection point between the high-resistance isolation branch and the first grounding path to control the branch's on / off state. Before performing the potential anchoring operation, the control unit sends a closing command to the relay, causing the relay's main contacts to conduct, thus connecting the high-resistance isolation branch to the first grounding path to form a high-impedance conducting loop. Next, a weak current path is established through this branch, causing a slow potential equalization process between the two grounding systems. After the potential difference decreases to the set range, the control unit releases the relay from its closed state, causing the high-resistance isolation branch to return to open state, thereby completing a high-resistance current-limiting potential anchoring operation and ensuring the coexistence of electrical isolation and potential balance between the grounding systems.

[0106] Calculate the GA-GB relative potential difference between the initial first potential rise value and the initial second potential rise value in the ground potential gradient vector;

[0107] Calculate the GA-GC relative potential difference between the initial first potential rise value and the initial third potential rise value in the ground potential gradient vector;

[0108] Specifically, the relay is used to control the connection and disconnection of the high-resistance isolation branch, enabling the grounding path to achieve controllable conduction when needed; the first grounding path represents the main grounding channel between the capacitor bank grounding point and the open delta PT grounding point, serving as the current reference path for potential anchoring; the GA–GB relative potential difference represents the potential difference amplitude between the first and second potential rise values ​​in the ground potential gradient vector, reflecting the degree of potential imbalance between the two grounding nodes; the GA–GC relative potential difference represents the potential difference between the first and third potential rise values, characterizing the three-point potential distribution relationship of the grounding network; by calculating the GA–GB and GA–GC relative potential differences, the potential offset between different grounding paths can be quantitatively analyzed, providing basic data for achieving equipotential anchoring and grounding balance adjustment.

[0109] Adjust the resistance of the high-resistance isolation branch until the relative potential difference between GA-GB and GA-GC drops to within the resolution range of the instrument measuring equipment;

[0110] Specifically, by adjusting the resistance of the high-resistance isolation branch until the relative potential difference between GA-GB and GA-GC falls within the resolution range of the instrument measuring equipment, the goal is to achieve precise equivalence of the potentials at each grounding point in a multi-point grounding system, thereby eliminating potential imbalances caused by differences in grounding resistance. When the high-resistance isolation branch is connected, a controlled micro-current discharge channel is formed. By gradually adjusting the resistance of this branch, the current distribution ratio between the two grounding systems can be changed, gradually balancing the potential difference between different grounding points. When the measured relative potential difference decreases to the minimum resolution of the measuring device, it indicates that the potentials of each grounding node are essentially consistent, the ground potential gradient approaches zero, and an ideal equipotential state is achieved. This process not only ensures the safe isolation of the electrical system but also eliminates the bias voltage caused by the common ground current effect, providing a precise reference for subsequent voltage measurement and bias correction after potential anchoring.

[0111] After the resistance adjustment process of the high-resistance isolation branch is completed, measure the first potential rise value after anchoring of the first grounding path, the second potential rise value after anchoring of the second grounding path, and the third potential rise value after anchoring of the third grounding path, and measure the output voltage of the open delta PT after anchoring.

[0112] Specifically, the first potential rise value after anchoring represents the stable potential rise of the grounding point corresponding to the first grounding path after the high-resistance isolation branch resistance adjustment is completed and potential balance is achieved. This value reflects the final potential distribution of the grounding node in the anchored state. The second potential rise value after anchoring represents the ground potential change formed by the second grounding path after potential anchoring is completed, reflecting the response characteristics of this path in the potential balance process. The third potential rise value after anchoring represents the potential rise value of the grounding point of the third grounding path after potential equalization is completed, reflecting the overall potential balance of the grounding network. The output voltage after anchoring represents the stable output voltage of the open delta PT after ground potential anchoring is completed. It is the true voltage measurement result obtained after eliminating ground bias interference. This voltage value serves as an accurate reference for subsequent bias mapping calculation and net residual voltage determination, providing a reliable input signal for transformer area voltage monitoring and energy storage regulation.

[0113] Specifically, after the resistance adjustment process of the high-resistance isolation branch is completed, the anchored potential rise values ​​of the first, second, and third grounding paths, as well as the anchored output voltage of the open delta PT, are measured. This is to obtain the stable potential distribution state and voltage detection reference value of each grounding point after achieving potential equipotentiality of the grounding system. After the gradual adjustment of the high-resistance isolation branch, the potential difference of the three grounding paths has been reduced to a minimum, and the system has entered a steady state. At this time, the measured anchored potential value can accurately reflect the true potential level of the grounding system under equipotential conditions. By simultaneously measuring the anchored output voltage of the open delta PT, the true output signal of the voltage transformer after eliminating the influence of the common ground current bias can be obtained. This signal serves as the reference input for voltage measurement and bias correction in the transformer substation area. Combining these measurement results, the correspondence between ground potential and voltage under anchored conditions can be established, providing accurate data support for subsequent bias mapping constant calculation, net residual voltage solution, and energy storage control.

[0114] Specifically, after the resistance adjustment process of the high-resistance isolation branch is completed, the potential of the three grounding paths between the capacitor bank grounding point and the open delta PT grounding point is sampled by the potential detection module. Under the condition that the high-resistance isolation branch is in a stable state and the potential difference drops to the resolution range of the measuring instrument, the steady-state potential values ​​of the grounding points corresponding to the first, second, and third grounding paths are recorded in sequence. Then, the difference between the potential value of each path and the reference ground potential before adjustment is calculated to obtain the first potential rise value, the second potential rise value, and the third potential rise value after anchoring. Next, the voltage acquisition device performs synchronous measurement at the open end of the open delta PT to obtain the steady-state output voltage of the PT after the potential anchoring is completed. Finally, the measured potential rise values ​​of the three grounding paths after anchoring and the output voltage of the open delta PT after anchoring are synchronously stored in the control unit to form a data set of ground potential and voltage correspondence under the anchoring state.

[0115] The first potential boost value, the second potential boost value, and the third potential boost value after anchoring are combined to form the anchoring potential boost vector.

[0116] Specifically, the anchored potential rise vector is used to represent the overall distribution characteristics of the potential change at the grounding point of each grounding path after the high-resistivity isolation branch adjustment is completed and potential balance is achieved. This vector is formed by the combination of the first, second, and third potential rise values ​​after anchoring, and each component corresponds to the steady-state potential rise amplitude of different grounding paths under the potential anchoring state. This vector reflects the degree of potential spatial balance and gradient distribution direction of the grounding system after achieving equipotential conditions. It can be used to describe the spatial relationship between the ground potential correction effect and the residual potential difference, providing accurate potential distribution model support for subsequent bias mapping constant calculation and voltage bias correction.

[0117] S4. Calculate the bias mapping constant corresponding to the common ground diversion effect in the target transformer area based on the initial output voltage, the output voltage after anchoring, the ground potential gradient vector, and the potential rise vector after anchoring.

[0118] In embodiments of the present invention, the bias mapping constant corresponding to the common ground diversion effect in the target transformer area is calculated based on the initial output voltage, the anchored output voltage, the ground potential gradient vector, and the anchored potential rise vector, including:

[0119] The difference between the initial output voltage and the anchored output voltage is calculated to obtain the output voltage difference.

[0120] Specifically, the output voltage difference is used to represent the magnitude of the output voltage change of the open delta PT before and after potential anchoring. Its value reflects the voltage measurement offset caused by the ground potential difference correction and is an important parameter characterizing the impact of the anchoring process on the voltage signal.

[0121] Calculate the total potential change based on the ground potential gradient vector and the potential rise vector after anchoring;

[0122] Specifically, the total potential change is used to represent the overall potential change obtained by combining the ground potential gradient vector and the potential rise vector after anchoring. Its value reflects the overall adjustment range of the potential at each grounding point during the potential anchoring process.

[0123] Specifically, when calculating the total potential change based on the ground potential gradient vector and the post-anchoring potential rise vector, the initial first potential rise value, initial second potential rise value, and initial third potential rise value contained in the ground potential gradient vector are first read, and the post-anchoring potential rise value, post-anchoring potential rise value, and post-anchoring potential rise vector are second read, third read, and post-anchoring potential rise value. Then, the difference between the initial potential rise value and the corresponding post-anchoring potential rise value of each grounding path is calculated to obtain the potential change of the first path, the potential change of the second path, and the potential change of the third path. Finally, the potential changes of the three paths are weighted or algebraically summed to obtain the total potential change of the entire transformer area. This total reflects the overall correction magnitude of the grounding system potential before and after the anchoring operation.

[0124] The bias mapping constant is obtained by calculating the ratio between the output voltage difference and the total potential change.

[0125] Specifically, the bias mapping constant is used to characterize the proportional relationship between the ground potential change caused by the common-ground current diversion effect and the output voltage deviation of the open-delta PT. It is an important parameter reflecting the degree to which ground potential disturbance is transmitted to voltage measurement. In the transformer substation grounding system, the capacitor bank and the secondary side of the PT share a grounding busbar. When the discharge current or residual voltage diversion current flows through the grounding network, it will cause a ground potential difference between different grounding points, thus forming a static voltage bias on the secondary side of the PT. The bias mapping constant is obtained by calculating the ratio of the output voltage difference to the total ground potential change. Its magnitude reflects the influence coefficient of the ground potential imbalance caused by the common-ground current diversion on the voltage measurement system. By determining this constant, the mapping relationship between ground potential disturbance and voltage deviation can be established, providing an accurate correction basis for subsequent bias compensation and net residual voltage solution, enabling the system to have the ability to offset the common-ground current interference.

[0126] Specifically, the calculation of the bias mapping constant is based on the proportional relationship between potential change and voltage change. By comparing the ratio of the change in output voltage of the open-delta PT before and after potential anchoring to the total potential change of each grounding path, a mapping coefficient between ground potential disturbance and voltage output offset is established. The total potential change reflects the overall potential correction amplitude of the grounding system due to the common ground current diversion effect, while the output voltage difference reflects the projected response of this potential change in the PT secondary voltage signal. Since the response of the PT secondary winding to ground potential change has a linear proportional characteristic, there is an approximately linear relationship between its voltage change and the ground potential gradient change. The bias mapping constant can be obtained by calculating the ratio of the two. The bias mapping constant represents the proportional constant of the voltage bias formed at the PT output terminal by the ground potential gradient change, and can quantitatively reflect the coupling degree of the bias effect.

[0127] It should be noted that the common-ground current diversion effect refers to the phenomenon where, when multiple electrical devices or measurement systems share the same grounding busbar or grounding grid, potential differences or residual charge release paths between different devices lead to an undesirable current distribution in the ground wire. When the discharge current of the capacitor bank, the leakage current of the PT secondary winding, or the return current of the energy storage device flows through the same grounding network, a weak voltage gradient is generated within the grounding grid, causing potential imbalances between different grounding points, thus affecting the reference zero point of the voltage transformer. This phenomenon causes a static bias voltage at the output terminal of the open-delta PT, causing the measurement signal, which should be at a symmetrical zero point, to deviate, thereby contaminating the residual voltage signal or misleading the voltage. The common-ground current diversion effect is closely related to the grounding impedance difference, the length of the grounding wire, and the distribution of the discharge path; its essence is the current redistribution problem caused by the shared grounding grid in the electrical system. By detecting and compensating for this effect, the reference correction for voltage measurement and the equalization control of the ground potential in the transformer area can be achieved.

[0128] S5. Based on the ground potential gradient vector and the bias mapping constant, calculate the net residual voltage of the open delta PT.

[0129] In an embodiment of the present invention, the net residual voltage of the open-delta PT is calculated based on the ground potential gradient vector and the bias mapping constant, including:

[0130] The initial first potential rise value, the initial second potential rise value, and the initial third potential rise value in the ground potential gradient vector are summed to obtain the total potential rise.

[0131] The bias voltage of the open delta PT is obtained by multiplying the sum of potential increases with the bias mapping constant.

[0132] The net residual voltage of the open delta PT is obtained by calculating the difference between the current measured output voltage and the bias voltage.

[0133] Specifically, the sum of potential increases represents the composite result of the potential rise of each grounding path in the ground potential gradient vector. It is obtained by summing the initial first, second, and third potential increases to obtain the overall potential increase of the system before bias correction. This value reflects the total ground potential offset formed by the accumulation of potential differences between the grounding paths. The bias voltage represents the equivalent manifestation of ground potential imbalance caused by the common-ground current diversion effect in the secondary voltage output of the open-delta PT. It is the product of the sum of potential increases and the bias mapping constant, characterizing the coupling effect of ground potential imbalance on the PT output signal. Its value can be considered as the static offset voltage at the PT output terminal. The net residual voltage represents the true residual voltage signal of the open-delta PT output after removing the bias voltage. It is obtained by calculating the difference between the current measured output voltage and the bias voltage. This value represents the effective voltage imbalance after bias immune correction, accurately reflecting the voltage asymmetry state caused by load or fault in the system, and is an important basis for subsequent energy storage scheduling and voltage quality control.

[0134] Specifically, the net residual voltage calculation of an open-delta PT is based on the voltage superposition principle and the ground potential correction law. Since the output voltage of the secondary side of an open-delta PT is simultaneously affected by both the actual voltage imbalance and the ground potential bias, with the bias voltage originating from the voltage coupling of the ground potential difference on the PT's secondary winding caused by the common-ground current diversion effect, the corresponding bias voltage can be obtained by summing the initial potential rise values ​​at each grounding point in the ground potential gradient vector and multiplying it by the bias mapping constant. This bias voltage is equivalent to the static component in the PT output related to the asymmetric coupling with the ground potential, while the measured PT output voltage includes both the actual residual voltage component and this bias component. Based on the voltage superposition and differential laws, subtracting the bias voltage from the measured output voltage eliminates the spurious component caused by the ground potential imbalance, yielding the actual residual voltage signal caused only by system load imbalance, phase sequence distortion, or local faults—that is, the net residual voltage of the open-delta PT. This effectively immunizes against the influence of bias, ensuring the accuracy of voltage imbalance detection.

[0135] It should be noted that the secondary side of an open-delta PT refers to the terminal circuit of the secondary winding of a voltage transformer connected in an open-delta configuration within a three-phase winding system. This structure consists of three-phase secondary windings connected end-to-end to form a closed triangle, with one corner disconnected, leaving two open terminals as outputs. The voltage at these output terminals reflects the imbalance of the three-phase voltage vector, i.e., the zero-sequence voltage component of the system. It can sensitively detect voltage anomalies in the distribution system caused by ground faults, phase-to-phase imbalances, or ground potential disturbances. Due to the high impedance isolation between the secondary side of the open-delta PT and ground, its output depends not only on the vector difference of the three-phase voltages but also on the common-ground current-carrying effect and changes in ground potential distribution. Therefore, a static voltage offset will occur at the output terminal when a potential bias exists. By biasing the secondary side output signal, the net residual voltage reflecting the true imbalance state of the system can be extracted, providing an accurate reference for power quality monitoring and protection control of the distribution system.

[0136] S6. Determine the active power of the energy storage system based on the energy balance difference of the target transformer area, and determine the reactive power of the energy storage system based on the net residual voltage.

[0137] In embodiments of the present invention, determining the active power of the energy storage system based on the energy balance difference of the target distribution area and determining the reactive power of the energy storage system based on the net residual voltage includes:

[0138] The difference between the total power generation of all photovoltaic inverters in the target area and the load power of the target area is calculated to obtain the energy balance difference of the area.

[0139] Based on the energy balance difference in the distribution area and the minimum and maximum allowable active power of the energy storage system in the target distribution area, the active power of the energy storage system is determined. The expression for the active power of the energy storage system is as follows:

[0140]

[0141] In the formula, It is the active power of the energy storage system in the target transformer area. It is the total power generation of all photovoltaic inverters. It is the load power of the target transformer area. It is the minimum permissible active power of the energy storage system. It is the maximum permissible active power of the energy storage system. It is due to poor energy balance in the distribution area;

[0142] Specifically, the active power of the energy storage system represents the actual power output or absorption of the energy storage device during operation in the distribution area, and is an important parameter for measuring the energy flow balance regulation effect of the energy storage system; the total power generation of all photovoltaic inverters represents the total power generation injected into the power supply side of the distribution area by all grid-connected photovoltaic inverters at a specific moment, and its magnitude varies with solar irradiance and environmental conditions; the load power represents the total power demand of each user in the distribution area at the same moment, reflecting the energy consumption level of the distribution area; the minimum allowable active power represents the minimum power limit that the energy storage system can safely absorb during charging operation, used to prevent overcharging of the energy storage or unstable low-power operation of the inverter; the maximum allowable active power represents the maximum power output capability that the energy storage system can output during discharging operation, used to prevent over-discharge or equipment overload; the energy balance difference of the distribution area represents the power deviation between supply and demand in the distribution area at a given moment. When the deviation is positive, it indicates that photovoltaic power generation is excessive, and when it is negative, it indicates that the load demand is greater than the power generation.

[0143] Specifically, the active power calculation of the energy storage system is based on the law of conservation of energy and the principle of power balance. Within the distribution area, the photovoltaic (PV) power generation, load power, and energy storage power satisfy an instantaneous power balance relationship, meaning the PV power generation equals the sum of the load power and the energy storage power. When PV output exceeds load demand, excess energy is absorbed by the energy storage system to form charging power; when PV output is less than load demand, the energy storage system releases energy to compensate for the power gap, forming discharging power. By calculating the difference between PV output and load power, the energy balance deviation of the distribution area can be obtained. By limiting this deviation to the allowable charging and discharging power range of the energy storage system, the active power of the energy storage system can be obtained. Using upper and lower limit projection constraints ensures that the energy storage power output does not exceed the safe operating limits of the equipment, while maintaining continuous and stable energy regulation.

[0144] Calculate the reactive power control quantity of the energy storage system based on the net residual voltage and the voltage-reactive power response slope of the target area.

[0145] Specifically, the voltage-reactive response slope represents the proportional relationship between the reactive power output change of an energy storage system and the voltage change in the distribution area. It is an important parameter reflecting the sensitivity of the energy storage device to voltage fluctuations. This slope is obtained by applying a small reactive power adjustment to the energy storage system and observing the corresponding voltage change; its value is equal to the ratio of the reactive power change to the voltage change. When the slope is large, the energy storage system responds quickly to voltage changes and can rapidly provide or absorb reactive power when the voltage deviates from the rated value. When the slope is small, the system adjustment is more gradual and is more suitable for stable scenarios with small voltage fluctuations. The reactive power control quantity refers to the target reactive power output value of the energy storage system calculated based on the current voltage deviation signal and the voltage-reactive power response slope, used to dynamically compensate for voltage deviations. Its calculation is based on the negative feedback control principle. When the voltage is too high, the system generates a negative reactive power control quantity to absorb reactive power, thereby reducing the voltage; when the voltage is too low, the system generates a positive reactive power control quantity to release reactive power, thereby increasing the voltage. Real-time adjustment of reactive power control enables the energy storage system to automatically maintain the stability of the voltage in the distribution area, achieving closed-loop control of distributed voltage quality.

[0146] Specifically, when calculating the reactive power control quantity of the energy storage system based on the net residual voltage and the voltage-reactive power response slope of the target transformer area, the voltage detection unit first collects the net residual voltage signal of the target transformer area in real time and inputs this voltage signal to the reactive power control module of the energy storage controller; then, it reads the voltage-reactive power response slope obtained after transformer area calibration from the system parameter database, which is the proportional coefficient of the energy storage system's response to voltage deviation; next, the control module performs a product operation according to the direction of voltage deviation, multiplying the net residual voltage value by the voltage-reactive power response slope, and introducing a negative feedback symbol to... The system ensures that the output reactive power control quantity is opposite to the voltage deviation direction, thereby achieving voltage stabilization regulation. When the net residual voltage is positive, the calculation result is negative, and the energy storage system absorbs reactive power to reduce the voltage. When the net residual voltage is negative, the calculation result is positive, and the energy storage system releases reactive power to increase the voltage. Finally, the obtained reactive power control quantity is subject to upper and lower limit constraints to ensure that it operates within the reactive power capacity range of the energy storage device. The limited reactive power command is then output to the energy storage converter for execution, thereby completing the dynamic adaptive control of the reactive power of the energy storage system and achieving automatic correction and steady-state maintenance of voltage quality.

[0147] Specifically, the voltage-reactive power response slope of the target distribution area is obtained through the on-site calibration process of the energy storage system. This process involves injecting small-amplitude reactive power changes into the distribution bus under stable voltage conditions, while continuously monitoring real-time changes in the bus voltage. As the energy storage system gradually increases or decreases reactive power output, the controller records the voltage change amplitude caused by each reactive power adjustment and forms a data sequence through multiple experiments. Subsequently, based on the linear relationship between multiple sets of reactive power changes and corresponding voltage changes, the proportional relationship between the two is calculated; this ratio is the voltage-reactive power response slope of the target distribution area. This slope reflects the sensitivity of the distribution area's power grid to reactive power regulation and characterizes the voltage response speed and amplitude when the energy storage system adjusts reactive power, serving as a fundamental parameter for achieving automatic voltage regulation control.

[0148] Based on the reactive power control parameters, the lower limit and upper limit of the reactive power of the energy storage system, the reactive power of the energy storage system is determined. The expression for the reactive power of the energy storage system is as follows:

[0149]

[0150] In the formula, It is the reactive power of the energy storage system. It is the lower limit of reactive power of the energy storage system. It is the upper limit of reactive power of the energy storage system. It is the voltage-reactive response slope. It is the net residual voltage. It is a reactive power control quantity.

[0151] Specifically, the reactive power calculation of an energy storage system is based on the linear regulation law between voltage and reactive power and the power balance principle of the electrical system. In a power distribution system, voltage deviation is positively correlated with reactive power. When the system voltage rises, reactive power needs to be absorbed to suppress the voltage increase; when the system voltage drops, reactive power needs to be released to support voltage recovery. The energy storage system determines the current voltage deviation relative to the rated value by detecting the magnitude and direction of the net residual voltage. Based on a pre-calibrated voltage-reactive power response slope, it converts the voltage deviation into a corresponding reactive power output command, thereby achieving automatic voltage regulation. Since the inverter of the energy storage device has capacity limitations, to ensure safe operation, the calculated reactive power needs to be limited to the maximum and minimum reactive power range. When the calculated value exceeds the upper limit, the maximum value is taken; when it falls below the lower limit, the minimum value is taken. Through this limited linear response relationship, the energy storage system can automatically adjust the reactive power output when the voltage changes, keeping the system voltage stable. The final output reactive power reflects the real-time response of the energy storage system to voltage deviation; therefore, the obtained value is the reactive power of the energy storage system.

[0152] Specifically, the reactive power of an energy storage system represents the amount of reactive power absorbed or output by the energy storage device during grid-connected operation to regulate voltage. Its magnitude and direction determine the supporting or suppressing effect of the energy storage system on the voltage of the distribution area. The lower limit of reactive power represents the maximum absorption capacity that the energy storage system can withstand when absorbing reactive power, used to prevent the inverter from excessively absorbing reactive power and causing operational instability. The upper limit of reactive power represents the maximum output capacity of the energy storage system when providing reactive power, used to ensure that the equipment does not exceed its design capacity during voltage compensation. Net residual voltage represents the voltage imbalance of the distribution area after bias elimination, and is a real-time signal reflecting the degree of voltage deviation from the rated value. Negative proportional term This indicates the amount of reactive power compensation provided by the energy storage system based on the direction of voltage deviation. When the voltage in the distribution area is too high, it outputs negative reactive power to absorb energy; when the voltage is too low, it outputs positive reactive power compensation voltage. Defined as a reactive power control quantity, it is used to achieve dynamic and stable regulation of the voltage in the distribution area by the energy storage system.

[0153] S7. Dynamically balance and control the photovoltaic absorption status of the target area based on active power and reactive power.

[0154] In embodiments of the present invention, dynamic equilibrium control of the photovoltaic absorption status of the target distribution area based on active power and reactive power includes:

[0155] Collect real-time photovoltaic power output and real-time user load power of the target area;

[0156] The charging and discharging of the energy storage system in the target area is scheduled based on the difference between real-time photovoltaic power output and real-time user load power, and the active power.

[0157] Specifically, real-time photovoltaic output power represents the instantaneous active power output to the grid by the photovoltaic power generation system within the target distribution area through the inverter at the current moment. It is the usable electrical energy rate generated by the photovoltaic modules under solar irradiance and temperature conditions. Real-time user load power represents the total power demand of all electrical equipment within the distribution area to the grid at the current moment, reflecting the electricity consumption level of the area. The difference between the two represents the energy balance state of the distribution area at that moment. When the photovoltaic output power is greater than the load power, it indicates that there is an energy surplus in the distribution area. When the photovoltaic output power is less than the load power, it indicates that there is an energy deficit in the distribution area. Active power dispatch represents the process by which the energy storage system automatically adjusts its charging and discharging based on this difference. By absorbing energy when there is an energy surplus and releasing energy when there is an energy shortage, it achieves dynamic energy balance within the distribution area and local photovoltaic consumption, thereby improving energy utilization and mitigating the impact of reverse power flow in the distribution network.

[0158] Specifically, when scheduling the charging and discharging of the energy storage system in the target distribution area based on the difference between real-time photovoltaic power output and real-time user load power, the energy management unit first retrieves the energy storage system's active power command determined earlier based on the energy balance difference in the distribution area. Simultaneously, at a cycle of no less than 1 second, the data acquisition units of the photovoltaic inverters deployed in the distribution area and the load monitoring terminal collect the sum of real-time photovoltaic power output from all photovoltaic inverters and the sum of real-time user load power from all electrical equipment in the distribution area, respectively. The real-time difference between the two is calculated to verify whether the current energy supply and demand status is consistent with the previously determined active power command. Then, the operating parameters of the energy storage system are called... The database extracts the upper and lower limits of the state of charge (SOC) of energy storage batteries, the safe temperature range of individual battery cells, and the power transmission limits of grid connection points for power distribution areas. It then performs compliance verification between the previously determined active power commands and the aforementioned constraints. If the charging power corresponding to the active power command exceeds the maximum allowable charging power of the energy storage system or causes the SOC to exceed the upper limit, the charging power is corrected to the maximum allowable charging power. If the corresponding discharging power exceeds the minimum allowable discharging power or causes the SOC to fall below the lower limit, the discharging power is corrected to the minimum allowable discharging power. Simultaneously, it ensures that the corrected active power does not trigger battery temperature alarms and does not exceed the grid connection point power limit. After successful verification, the energy state is determined based on the real-time difference. The system determines the operating mode of the energy storage system. If the difference is positive (i.e., photovoltaic surplus), it is set to charging mode; if the difference is negative (i.e., energy deficit), it is set to discharging mode. A scheduling message is generated, containing the corrected active power setpoint, power change slope, start / stop control signals, and overvoltage, overcurrent, and overtemperature safety interlock commands. This message is sent to the energy storage converter via industrial Ethernet or a dedicated 5G communication link. During scheduling execution, the actual active power output value and the energy storage system operating status are collected in real time at a frequency of 500 milliseconds / time through the grid connection point power sensor and the energy storage converter status monitoring module. If the deviation between the actual output value and the command value exceeds ±3% of the rated power or an abnormal operating status occurs, the power command is immediately fine-tuned. To ensure stable operation, real-time photovoltaic power output and real-time user load power data are collected every 5 seconds. The difference is recalculated and combined with the latest state of charge and temperature data of the energy storage system. Active power commands and dispatch messages are updated on a rolling basis to ensure that when photovoltaic output is excessive, the energy storage system can absorb excess power in a timely manner to avoid photovoltaic power being fed back to the upper-level grid. When photovoltaic output is insufficient, it can release power in a timely manner to supplement the load demand of the distribution area. The local energy supply and demand deviation of the distribution area is continuously controlled within ±2% of the rated power. Ultimately, through this dynamic dispatch process, the photovoltaic absorption status of the target distribution area is kept in dynamic equilibrium, while reducing the impact of energy fluctuations in the distribution area on the upper-level distribution network.

[0159] Collect real-time grid node voltages for the target transformer area;

[0160] Obtain the rated voltage of the power grid nodes in the target distribution area;

[0161] The reactive power compensation scheduling of the energy storage system is carried out based on the deviation between the real-time grid node voltage and the rated voltage, and the reactive power.

[0162] Specifically, real-time grid node voltage represents the instantaneous voltage value of key nodes in the distribution system during operation. It is an important parameter for monitoring grid voltage quality and dynamic changes. This value is obtained by real-time sampling from voltage transformers or intelligent monitoring devices. Rated voltage represents the standard voltage level that the node should maintain under design and normal operating conditions. It is a reference benchmark for assessing voltage deviation and implementing voltage regulation control. The deviation between real-time grid node voltage and rated voltage represents the magnitude and direction of the difference between the real-time grid node voltage and the rated voltage. Its value reflects the degree to which the current voltage is too high or too low, and is an important basis for judging the system voltage stability. Reactive power compensation dispatch represents the process by which the energy storage system automatically adjusts the output or absorption of reactive power according to the node voltage deviation. When the voltage is too high, the energy storage system absorbs reactive power to reduce the voltage. When the voltage is too low, the energy storage system releases reactive power to increase the voltage, thereby achieving real-time stability and dynamic balance control of the distribution area voltage.

[0163] Specifically, when performing reactive power compensation scheduling for the energy storage system based on the deviation between the real-time grid node voltage and the rated voltage, and the reactive power, the real-time grid node voltage of the key distribution node in the target distribution area is first collected by the distribution area voltage monitoring unit at a frequency of no less than 50 milliseconds / time. At the same time, the rated voltage parameter of the node is retrieved and the deviation between the two is calculated. The deviation value is the real-time grid node voltage minus the rated voltage. A positive value indicates that the voltage is too high, and a negative value indicates that the voltage is too low. Then, the reactive power command of the energy storage system determined earlier based on the net residual voltage is retrieved and combined with the energy storage converter. The reactive power adjustment range is defined as the lower and upper limits of reactive power. Boundary checks are performed on the command. If the command value is less than the lower limit, it is corrected to the lower limit; if it is greater than the upper limit, it is corrected to the upper limit. Simultaneously, it is ensured that the corrected reactive power command matches the direction of the current voltage deviation. That is, when the voltage is high, the command is a positive value absorbing reactive power; when the voltage is low, the command is a negative value releasing reactive power. After successful verification, a command is generated containing the corrected reactive power setpoint and the reactive power change slope (not exceeding the maximum allowable reactive power adjustment rate of the energy storage converter). Control messages indicating voltage regulation mode and voltage over-limit protection thresholds are sent to the energy storage converter via a dedicated communication link. During dispatch execution, voltage transformers track grid node voltage changes in real time, calculating a new voltage deviation value every 200 milliseconds. If this deviation value deviates from the expected voltage regulation effect corresponding to the corrected reactive power command by more than ±2% of the rated voltage, the reactive power command is dynamically adjusted to accelerate the voltage regulation response. Simultaneously, based on changes in real-time photovoltaic output and real-time user load power in the distribution area, reactive power compensation demand is reassessed every 5 seconds. If the photovoltaic... If a sudden increase in output causes a rapid rise in voltage or a sudden increase in load causes a rapid drop in voltage, the reactive power regulation slope is temporarily increased to suppress voltage fluctuations. Through the above process, the energy storage system can quickly absorb reactive power to reduce node voltage when the voltage is too high and release reactive power in a timely manner to increase node voltage when the voltage is too low. This stabilizes the real-time grid node voltage within ±5% of the rated voltage, providing a stable grid-connected voltage environment for the photovoltaic inverter. This avoids photovoltaic output limitations or inverter disconnection due to abnormal voltage, thereby ensuring the dynamic balance of photovoltaic consumption in the target area.

[0164] It should be noted that the photovoltaic consumption status of the target distribution area refers to the comprehensive balance of the electricity generated by the photovoltaic power generation system in the target distribution area under the current operating conditions, which is consumed by the local load of the distribution area, stored by the energy storage system, and transmitted to the upper-level power grid. Its core is reflected in the local consumption ratio of photovoltaic power, the matching degree of energy supply and demand in the distribution area, and the coordination of voltage stability.

[0165] like Figure 2 The diagram shown is a functional block diagram of a photovoltaic power distribution system based on energy storage provided in an embodiment of the present invention.

[0166] In this embodiment, the functions of each module / unit are as follows:

[0167] The topology identification module is used to generate a topology fingerprint vector between the capacitor bank grounding point and the open delta PT grounding point;

[0168] The ground potential modeling module is used to generate a ground potential gradient vector based on the topological fingerprint vector and the residual voltage current of the capacitor bank, and to measure the initial output voltage of the open delta PT.

[0169] The equipotential anchoring module is used to measure the anchored output voltage of the open delta PT based on the ground potential gradient vector, and to generate the anchored potential rise vector.

[0170] The bias calculation module is used to calculate the bias mapping constant corresponding to the common ground diversion effect in the target transformer area based on the initial output voltage, the output voltage after anchoring, the ground potential gradient vector, and the potential rise vector after anchoring.

[0171] The net residual voltage calculation module is used to calculate the net residual voltage of an open-delta PT based on the ground potential gradient vector and the bias mapping constant.

[0172] The energy storage power scheduling module is used to determine the active power of the energy storage system based on the energy balance difference of the target transformer area, and to determine the reactive power of the energy storage system based on the net residual voltage.

[0173] The photovoltaic equalization control module is used to dynamically equalize the photovoltaic absorption status of the target area based on active power and reactive power.

[0174] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for energy storage-based balancing and consumption control of a photovoltaic power station, characterized in that, The method comprises the following steps: S1, generating a topological fingerprint vector between the grounding point of the capacitor cabinet and the grounding point of the open-delta PT; S2, generating a ground potential gradient vector according to the topological fingerprint vector and the residual voltage current of the capacitor cabinet, and measuring the initial output voltage of the open-delta PT; S3, measuring the anchored output voltage of the open-delta PT according to the ground potential gradient vector, and generating an anchored potential lifting vector; S4, calculating a bias mapping constant corresponding to the common ground current effect in the target area according to the initial output voltage, the anchored output voltage, the ground potential gradient vector and the anchored potential lifting vector; S5, calculating the net residual voltage of the open-delta PT based on the ground potential gradient vector and the bias mapping constant; S6, determining the active power of the energy storage system based on the energy balance difference of the target area, and determining the reactive power of the energy storage system based on the net residual voltage; S7, dynamically balancing and controlling the photovoltaic consumption state of the target area based on the active power and the reactive power.

2. The energy storage based distribution area photovoltaic balancing accommodation control method according to claim 1, characterized in that, Generating a topological fingerprint vector between the grounding point of the capacitor cabinet and the grounding point of the open-delta PT comprises: Performing four-terminal resistance measurement on the first grounding path between the grounding point of the capacitor cabinet and the grounding point of the open-delta PT to obtain a first equivalent grounding resistance; Performing four-terminal resistance measurement on the second grounding path between the grounding point of the capacitor cabinet and the grounding point of the open-delta PT to obtain a second equivalent grounding resistance; Performing four-terminal resistance measurement on the third grounding path between the grounding point of the capacitor cabinet and the grounding point of the open-delta PT to obtain a third equivalent grounding resistance; Combining the first equivalent grounding resistance, the second equivalent grounding resistance and the third equivalent grounding resistance into a topological fingerprint vector. 3.The energy storage based distribution area photovoltaic balancing accommodation control method according to claim 1, characterized in that, Generating a ground potential gradient vector according to the topological fingerprint vector and the residual voltage current of the capacitor cabinet comprises: Reading the residual voltage value of the capacitor in the capacitor cabinet; Reading the nominal resistance value of the discharge resistance in the capacitor cabinet; Dividing the residual voltage value by the nominal resistance value to obtain the residual voltage current; Multiplying the first equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain an initial first potential lifting value; Multiplying the second equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain an initial second potential lifting value; Multiplying the third equivalent grounding resistance of the topological fingerprint vector by the residual voltage current to obtain an initial third potential lifting value; Combining the initial first potential lifting value, the initial second potential lifting value and the initial third potential lifting value to obtain a ground potential gradient vector.

4. The energy storage based distribution area photovoltaic balancing accommodation control method according to claim 1, characterized in that, Measuring the anchored output voltage of the open-delta PT according to the ground potential gradient vector, and generating an anchored potential lifting vector, comprises: Connecting the high-resistance isolation branch through a relay to the first grounding path; Calculating the GA-GB relative potential difference between the initial first potential lifting value and the initial second potential lifting value in the ground potential gradient vector; Calculating the GA-GC relative potential difference between the initial first potential lifting value and the initial third potential lifting value in the ground potential gradient vector; Adjusting the resistance value of the high-resistance isolation branch until the GA-GB relative potential difference and the GA-GC relative potential difference are within the resolution range of the instrument measuring device; When the adjustment process of the resistance value of the high-resistance isolation branch ends, the first potential lifting value after anchoring of the first ground path, the second potential lifting value after anchoring of the second ground path, and the third potential lifting value after anchoring of the third ground path are measured, and the output voltage after anchoring of the open-delta PT is measured; The first potential lifting value after anchoring, the second potential lifting value after anchoring, and the third potential lifting value after anchoring are combined into a potential lifting vector after anchoring.

5. The energy storage based distribution area photovoltaic balancing accommodation control method according to claim 1, characterized in that, According to the initial output voltage, the output voltage after anchoring, the ground potential gradient vector, and the potential lifting vector after anchoring, a bias mapping constant corresponding to the common ground current effect in the target area is calculated, including: The initial output voltage and the output voltage after anchoring are subtracted to obtain an output voltage difference; According to the ground potential gradient vector and the potential lifting vector after anchoring, the total potential change is calculated; The output voltage difference and the total potential change are divided to obtain the bias mapping constant.

6. The energy storage based distribution area photovoltaic balancing accommodation control method according to claim 1, characterized in that, Based on the ground potential gradient vector and the bias mapping constant, the net residual voltage of the open-delta PT is calculated, including: The initial first potential lifting value, the initial second potential lifting value, and the initial third potential lifting value in the ground potential gradient vector are summed to obtain a total potential lifting value; The total potential lifting value and the bias mapping constant are multiplied to obtain a bias voltage value of the open-delta PT; The current measured output voltage of the open-delta PT and the bias voltage value are subtracted to obtain the net residual voltage of the open-delta PT.

7. The energy storage based distribution area photovoltaic balancing accommodation control method according to claim 1, characterized in that, Based on the energy balance difference of the target area, the active power of the energy storage system is determined, and based on the net residual voltage, the reactive power of the energy storage system is determined, including: The total power generation of all photovoltaic inverters in the target area and the load power of the target area are subtracted to obtain the energy balance difference of the target area; Based on the energy balance difference of the target area, the minimum allowed active power and the maximum allowed active power of the energy storage system in the target area, the active power of the energy storage system is determined; According to the net residual voltage and the voltage-reactive power response slope of the target area, the reactive control amount of the energy storage system is calculated; According to the reactive control amount, the lower limit and the upper limit of the reactive power of the energy storage system, the reactive power of the energy storage system is determined. 8.The energy storage based distribution area photovoltaic balancing accommodation control method according to claim 1, characterized in that, Based on the active power and the reactive power, the dynamic balance control of the photovoltaic consumption state of the target area is performed, including: The real-time photovoltaic output power and the real-time user load power of the target area are collected; According to the difference between the real-time photovoltaic output power and the real-time user load power, the active power is used to schedule the charging and discharging of the energy storage system in the target area; The real-time grid node voltage of the target area is collected; The rated voltage of the grid node in the target area is obtained; According to the deviation between the real-time grid node voltage and the rated voltage, the reactive power is used for reactive power compensation scheduling of the energy storage system.

9. The energy storage-based photovoltaic balancing consumption control system for a transformer area, characterized in that, The system includes: A topology identification module is configured to generate a topology fingerprint vector between the capacitor cabinet grounding point and the open-delta PT grounding point; A ground potential modeling module is configured to generate a ground potential gradient vector based on the topology fingerprint vector and the residual voltage current of the capacitor cabinet, and measure the initial output voltage of the open-delta PT; An equipotential anchoring module is configured to measure an output voltage of the open-delta PT after anchoring according to a ground potential gradient vector and generate an anchoring-after potential lifting vector; A bias calculation module is configured to calculate a bias mapping constant corresponding to a common ground current effect in the target area according to the initial output voltage, the anchoring-after output voltage, the ground potential gradient vector and the anchoring-after potential lifting vector; A net residual voltage calculation module is configured to calculate a net residual voltage of the open-delta PT based on the ground potential gradient vector and the bias mapping constant; An energy storage power scheduling module is configured to determine an active power of the energy storage system based on an energy balance difference of the target area, and determine a reactive power of the energy storage system based on the net residual voltage; A photovoltaic balancing control module is configured to perform dynamic balancing control on a photovoltaic consumption state of the target area based on the active power and the reactive power.

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