Regulation and treatment method for reverse heavy overload and overvoltage of active transformer area

Abstract

The invention discloses a regulation and treatment method for reverse heavy overload and overvoltage of an active transformer area, the transformer area is connected with a plurality of distributed photovoltaic inverters, and the method comprises the following steps: configuring an acquisition period according to the access scale and operation characteristics of the distributed photovoltaic inverters in the transformer area, periodically collecting operation parameters of the transformer area and operation parameters of each distributed photovoltaic inverter; the transformer area operation parameters at least comprise distribution transformer capacity, total active power and maximum outlet voltage, and the distributed photovoltaic inverter operation parameters at least comprise active power, reactive power, real-time voltage and operation state; the regulation and control modes are started according to the priority sequence, the priority is divided into a reverse heavy overload regulation and control mode, an overvoltage regulation and control mode and a power recovery regulation and control mode from high to low, after a regulation and control instruction is issued every time, a new round of operation parameter collection is triggered immediately, the grading mode regulation and control are started, and a regulation and control closed loop is formed.

Description

Technical Field

[0001] This invention relates to the field of power systems and their automation technology, specifically to the operation control and anomaly management technology of active distribution transformer areas with distributed photovoltaic access, and particularly to a method for regulating and managing reverse heavy overload and overvoltage in active distribution transformer areas with variable loads. Background Technology

[0002] The development of distributed photovoltaic (PV) power is currently very rapid, with its installed capacity continuously increasing amidst the energy transition. Especially at the distribution network's end-point substation level, the decentralized connection of numerous distributed PV inverters has become commonplace. While this decentralized power generation model effectively improves the utilization rate of renewable energy, it has also fundamentally altered the traditional "unidirectional power flow" operating characteristics of the distribution network, posing unprecedented challenges to grid regulation. To address the intermittency and volatility of PV power output, the industry has developed various regulation technologies, among which maximum power point tracking (MPPT) and energy storage systems working together are the two most widely used.

[0003] The core objective of maximum power point tracking (MPPT) technology is to adjust the operating state of photovoltaic (PV) modules in real time through algorithms to track the maximum power output under different illumination and temperature conditions. Common implementation paths include perturbation observation and incremental conductance methods. However, these technologies have significant limitations: From a hardware perspective, they place stringent requirements on circuit sampling accuracy and the response speed of power switching devices. The series and parallel connection method of the PV array also directly affects the tracking effect, significantly increasing equipment costs and maintenance difficulty. From an algorithmic perspective, in complex illumination scenarios such as partial shading, the power-voltage curve of the PV array will exhibit multiple local peaks. Traditional algorithms are prone to getting trapped in local optima rather than the global maximum power point, leading to a significant decrease in power generation efficiency. More importantly, when illumination intensity changes rapidly, the algorithm's dynamic response lag can cause drastic fluctuations in output power, not only reducing power generation stability but also potentially impacting subsequent power electronic equipment.

[0004] Energy storage systems, when coordinated with regulation, balance photovoltaic output and load demand through "storage, release, and consumption," theoretically effectively mitigating power fluctuations. However, this approach faces multiple bottlenecks in practical applications: First, energy storage batteries have high initial investment costs and limited cycle life; frequent charging and discharging accelerate battery aging, making long-term economic viability difficult to guarantee. Second, coordinated control of photovoltaics and energy storage is challenging. Existing systems often employ fixed charging and discharging strategies, failing to adjust in real-time to dynamic scenarios such as sudden changes in sunlight and load fluctuations. This frequently results in insufficient energy storage capacity when photovoltaic output surges and delayed energy storage release when output drops sharply. In extreme weather conditions, these systems may even automatically shut down due to protection mechanisms, exacerbating grid fluctuations. Furthermore, the power characteristics of energy storage devices and photovoltaic inverters require high compatibility, and information barriers between different brands of equipment further weaken the synergistic effect.

[0005] In addition to the aforementioned technical deficiencies, existing control schemes generally overlook two key risk points that directly threaten grid security: reverse overload and overvoltage of distributed photovoltaic (PV) equipment. Reverse overload often occurs during peak PV output periods when local load is low. When the total power generation of distributed PV far exceeds the load demand of the distribution area, the excess power will be injected back into the upstream grid through the distribution transformer, forming a reverse power flow. If the reverse power exceeds the rated capacity of the distribution transformer, it will cause a sharp rise in winding temperature, accelerate the aging of insulation materials, significantly shorten equipment life, and in severe cases, trigger malfunctions of protection devices, leading to unplanned power outages. Traditional distribution network planning has not considered such reverse power flow scenarios, and existing control technologies have not designed specific protection mechanisms for this problem.

[0006] Overvoltage issues with distributed photovoltaic (PV) systems are particularly pronounced in high-penetration distribution areas. As the proportion of PV installations increases, the voltage at the end of the distribution network continuously rises due to active power injection. Coupled with the limited reactive power regulation capabilities of distributed PV inverters, this easily creates a vicious cycle of "voltage rise - reactive power excess." When the inverter's real-time voltage exceeds its tolerance threshold, its overvoltage protection automatically triggers a shutdown, causing not only power generation losses but also potentially triggering a chain reaction, further destabilizing the voltage in the distribution area. More importantly, existing control schemes often focus on optimizing the output of individual units, lacking coordinated management of the overall voltage level of the distribution area, resulting in recurring overvoltage problems during periods of intense sunlight.

[0007] Due to the excessive complexity of existing control technologies, which place high demands on the hardware precision and algorithm adaptability of distributed photovoltaic (PV) equipment, and the lack of effective protection systems against the two major grid risks of reverse overload and equipment overvoltage, the regional-level management of distributed PV remains a major problem for power companies. How to simplify control logic and reduce hardware dependence while accurately addressing these two types of hidden risks has become a core requirement for ensuring the safe and stable operation of active photovoltaic distribution areas. Summary of the Invention

[0008] In view of the defects and deficiencies of the existing technology, the present invention provides a method, system and computer equipment for coordinated regulation and control of reverse heavy overload and overvoltage in active power distribution areas, aiming to solve the problems that the existing control technology is complex, highly dependent on hardware, and ignores the risks of reverse heavy overload and overvoltage of photovoltaic equipment.

[0009] This invention uses a periodically configurable data acquisition mechanism to dynamically set the acquisition period based on the access scale and operating characteristics of distributed photovoltaic inverters in the distribution area. It simultaneously acquires parameters such as the distribution transformer capacity, total active power, and maximum output voltage of the distribution area, as well as the active power, reactive power, real-time voltage, and operating status of the inverters. During the acquisition process, faulty equipment is eliminated to ensure the validity of the data. The core adopts a hierarchical priority control mode, performing operations in the order of reverse heavy overload control, overvoltage control, and power recovery control: When the absolute value of the total active power in the distribution area exceeds the product of the transformer capacity and the preset ratio, a unified adjustment ratio is calculated based on the total power generation of the adjustable inverter to determine the active power limit value of each device; when the inverter voltage reaches the maximum value among the preset overvoltage start threshold, the converted value of the 220V reference value, and the superimposed value of the maximum outlet voltage of the distribution area, the inductive reactive power is reduced first with a preset granularity, and if this is ineffective, the active power is reduced, and the number of reactive power adjustments does not exceed the preset maximum number of rounds; when the duration of no reverse heavy overload and overvoltage in the distribution area exceeds the corresponding preset stabilization time, the overvoltage power limit is first lifted, then the overvoltage equipment is excluded, and the active power limit release value is calculated according to a unified ratio to ensure that it does not exceed the rated power of the equipment. After each control command is issued, parameters are immediately re-collected and the control process is restarted according to the original priority, forming a closed-loop mechanism. All preset ratios, thresholds, time and other parameters are configurable based on the distribution transformer capacity, total photovoltaic installed capacity and grid standards. The uniform adjustment ratio is applicable to all controllable equipment, ensuring fairness for users.

[0010] This invention requires no additional hardware. By simplifying the control logic and establishing a precise coordination mechanism, it effectively prevents transformer damage caused by reverse overload and equipment shutdown risks caused by overvoltage. While improving the operational safety and stability of active power distribution areas, it maximizes the utilization rate of photovoltaic power output and reduces operation and maintenance costs.

[0011] The present invention specifically adopts the following technical solution: A method for regulating and mitigating reverse heavy overload and overvoltage in an active power distribution area, wherein the distribution area is connected to multiple distributed photovoltaic inverters, including: Based on the grid connection scale and operating characteristics of the distributed photovoltaic inverters in the distribution area, a data acquisition cycle is configured to periodically collect the operating parameters of the distribution area and the operating parameters of each distributed photovoltaic inverter. The operating parameters of the distribution area include at least the transformer capacity, total active power, and maximum output voltage, while the operating parameters of the distributed photovoltaic inverters include at least the active power, reactive power, real-time voltage, and operating status. Tiered mode control: Control modes are activated in order of priority, from highest to lowest: reverse overload control mode, overvoltage control mode, and power recovery control mode. Reverse overload control mode: When the absolute value of the reverse of the total active power of the distribution area is greater than the first power threshold determined by the product of the distribution transformer capacity and the first preset proportional coefficient, the goal is to reduce the reverse power to the second power threshold determined by the product of the distribution transformer capacity and the second preset proportional coefficient. Based on the current total power generation of all controllable inverters, a unified power adjustment ratio is calculated, the active power limit value of each inverter is determined, and a control command is issued. Overvoltage control mode: When the real-time inverter voltage is greater than or equal to the overvoltage threshold value determined by the maximum value among the conversion value of the preset overvoltage start threshold and the normal voltage reference value, and the superposition value of the maximum output voltage of the transformer area and the preset voltage increment, the reactive power is reduced first with the preset reactive power adjustment granularity; if it is still overvoltage, the active power is reduced with the preset active power adjustment granularity and a control command is issued. Power recovery control mode: When the duration of no reverse heavy overload in the distribution area exceeds the preset overpower stabilization time and the duration of no overvoltage in the inverter exceeds the preset overvoltage stabilization time, the overvoltage power limit is first lifted, then the overvoltage inverter is excluded. The unified power adjustment ratio is calculated based on the maximum threshold of the active power control target determined by the product of the distribution transformer capacity and the third preset proportional coefficient. The active power limit release value of the normal inverter is determined and the instruction is issued. Each time a control command is issued, a new round of operating parameter collection is immediately triggered, and a tiered control mode is initiated to form a control closed loop.

[0012] Furthermore, the periodic data collection specifically includes: parallel reading of data from all normally operating distributed photovoltaic inverters and AC data collected from the distribution area, excluding distributed photovoltaic inverters in a faulty state; the collection period is a parameter dynamically configured based on the number of distributed photovoltaic inverters connected to the distribution area and the load fluctuation frequency of the distribution area.

[0013] Furthermore, in the reverse heavy overload control mode, the calculation method of the unified power adjustment ratio is: (second power threshold + total active power of the distribution area) ÷ current total power generation of all adjustable inverters; the adjustable inverter is a distributed photovoltaic inverter that is in normal operating condition and can be set with a lower active power limit value, and the active power limit value of each inverter is determined based on the unified power adjustment ratio.

[0014] Furthermore, in the overvoltage control mode, the conversion method between the preset overvoltage start threshold and the conventional voltage reference value is: preset overvoltage start threshold × 0.001 × conventional voltage reference value; the reduction of reactive power specifically means reducing the inductive reactive power output of the inverter, and the inductive reactive power is represented by a negative value; and the number of reactive power adjustments does not exceed the preset maximum number of overvoltage reactive power adjustments.

[0015] Furthermore, in the power recovery control mode, the calculation method of the unified power adjustment ratio is: (maximum threshold of active power control target + total active power of the distribution area) ÷ current total power generation of all normal inverters; the normal inverter is a distributed photovoltaic inverter with normal operating status and real-time voltage below the overvoltage threshold value, and the active power limit release value of each inverter is determined based on the unified power adjustment ratio, and the limit release value does not exceed the rated active power of the inverter.

[0016] Furthermore, the real-time closed-loop feedback specifically includes: after issuing the control command, immediately starting a new round of data acquisition, after the acquisition is completed, first determining whether there is still reverse heavy overload in the transformer area, then determining the overvoltage status and power recovery conditions in sequence, and executing the corresponding control mode in the original priority order until no control command needs to be issued.

[0017] Furthermore, the unified power adjustment ratio applies uniformly to all adjustable inverters or normal inverters, ensuring that the power adjustment range of each distributed photovoltaic inverter is proportional to its current power generation.

[0018] Furthermore, the first preset proportional coefficient, the second preset proportional coefficient, the third preset proportional coefficient, the preset overvoltage start threshold, the preset voltage increment, the preset reactive power regulation granularity, the preset active power regulation granularity, the preset overpower stabilization time, and the preset overvoltage stabilization time are all configurable parameters preset based on the distribution transformer capacity, the total installed capacity of distributed photovoltaic power and the grid operation standards.

[0019] Furthermore, a coordinated regulation and control system for reverse heavy overload and overvoltage in an active power distribution area, wherein the distribution area is connected to multiple distributed photovoltaic inverters, including: The data acquisition module is used to configure the acquisition cycle according to the access scale and operating characteristics of the distributed photovoltaic inverters in the distribution area, and to periodically acquire the operating parameters of the distribution area and the operating parameters of each distributed photovoltaic inverter; the operating parameters of the distribution area include at least the transformer capacity, total active power, and maximum output voltage, and the operating parameters of the distributed photovoltaic inverters include at least the active power, reactive power, real-time voltage, and operating status; Hierarchical control module: used to activate control modes in order of priority, from high to low priority: reverse heavy overload control mode, overvoltage control mode, and power recovery control mode, and can generate and issue corresponding control commands; Closed-loop feedback module: After each control command is issued, it immediately triggers the adaptation acquisition module to reacquire operating parameters and drives the hierarchical control module to start a new round of hierarchical mode control, forming a flexible and collaborative control closed loop.

[0020] And an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the program to implement the steps of the method described above.

[0021] A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of the method described above.

[0022] Compared with the prior art, the present invention and its preferred embodiments have at least the following beneficial effects: First, it effectively fills the gap in existing technology for core risk protection of active power distribution areas. Through a targeted, tiered control mechanism, it precisely addresses two previously overlooked hidden dangers: reverse overload and overvoltage of distributed photovoltaic equipment. Specific measures for reverse overload can prevent equipment aging or malfunctioning protection systems caused by reverse power flow overload. The "reactive power priority, active power supplement" control for overvoltage can reduce power generation losses caused by equipment shutdowns due to overvoltage, significantly improving the operational safety and stability of the power grid and photovoltaic system.

[0023] Secondly, it significantly simplifies the control logic and reduces hardware dependence. This invention abandons the complex algorithm design and high-precision hardware requirements of existing technologies. Through a periodically configurable acquisition mechanism and a unified power adjustment ratio calculation logic, it reduces the technical implementation difficulty while ensuring the control effect. Moreover, it does not require additional hardware equipment and can be implemented using only existing acquisition channels and control interfaces. Combined with the convenience of remote data monitoring and fault diagnosis, it can effectively reduce operation and maintenance time and costs, and improve economic efficiency.

[0024] Furthermore, it balances user fairness and maximizing photovoltaic output during the regulation process. The unified power adjustment ratio applies to all adjustable distributed photovoltaic inverters, ensuring that the power adjustment range of each device matches its own operating status and avoiding regulation imbalances between individuals. At the same time, the power recovery regulation mode, through time constraints and priority design, gradually removes power restrictions when the load in the distribution area and the equipment status allow, achieving efficient utilization of solar energy resources and balancing grid security and energy utilization efficiency.

[0025] Finally, it possesses excellent scenario adaptability and timely control. All preset parameters can be flexibly configured according to the transformer capacity, photovoltaic installation scale, and grid standards of the distribution area, adapting to active distribution areas with different access characteristics; and the instant closed-loop feedback mechanism after the control command is issued can quickly respond to changes in operating conditions, reduce ineffective control operations, and further ensure the reliability of the solution under dynamic illumination and load fluctuation scenarios. Attached Figure Description

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 This is a flowchart illustrating the overall process of the flexible control algorithm for coordinated regulation and mitigation of reverse heavy overload and overvoltage in active power distribution areas according to an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the specific execution flow of the reverse overload judgment and processing module in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the specific execution flow of the distributed photovoltaic overvoltage power limitation judgment and processing module in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the specific execution flow of the distributed photovoltaic overvoltage power limitation release judgment and processing module in an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the specific execution flow of the distributed photovoltaic power release active power limitation judgment and processing module in an embodiment of the present invention. Detailed Implementation

[0027] In the following, specific embodiments of this application will be described in detail with reference to the accompanying drawings. Based on these detailed descriptions, those skilled in the art will be able to clearly understand and implement this application. Without departing from the principles of this application, features from various embodiments can be combined to obtain new implementations, or certain features from some embodiments can be substituted to obtain other preferred implementations.

[0028] To make the features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings: This invention monitors the reverse overload conditions of the distribution transformer area and the operating parameters of the distributed photovoltaic (PV) equipment in real time. In the event of a reverse overload or overvoltage in the PV equipment, a flexible control algorithm is used to calculate and adjust the PV equipment while ensuring fairness to users, until the abnormal situation is resolved. Even when the load conditions in the distribution transformer area and the operating status of the PV equipment permit, the flexible control algorithm still adjusts the PV equipment to ensure maximum active power output. The flexible control algorithm is simple, reducing the possibility of system instability due to algorithm complexity.

[0029] The present invention will be shown and described in more detail below with reference to the accompanying drawings and embodiments: 1. Terms and Definitions Distribution transformer capacity in the area: Load, unit: KVA. Data source: Data collected from the transformer substation area.

[0030] Total active power of the transformer area: totW, unit W, coefficient -1. Data source: collected from transformer substations.

[0031] Maximum active power threshold for transformer area: totVarMax, unit Var, coefficient -1. Data source: calculated.

[0032] Minimum threshold for active power regulation target of the transformer area: totVarTargetMin, unit Var, coefficient -1. Data source: calculated.

[0033] Maximum threshold for active power regulation target in the distribution area: totVarTargetMax, unit Var, coefficient -1. Data source: calculated.

[0034] Maximum output voltage of the transformer area: phV_Max, unit V, coefficient -1. Data source: collected from transformer substations.

[0035] Maximum percentage of reverse load rate: ThresholdMaxRate, in % (coefficient -1). Data source: via preset parameters.

[0036] Minimum percentage of reverse load rate target: ThresholdTargetMinRate, in % (coefficient -1). Data source: via preset parameters.

[0037] Reverse load rate target value maximum percentage: ThresholdTargetMaxRate, in % (coefficient -1). Data source: via preset parameters.

[0038] Desired controllable power value: powerOffsetMaxControl, unit W, coefficient -1. Data source: calculated.

[0039] Current total power generation: sumCurrPower, unit W, coefficient -1. Data source: calculated.

[0040] Overvoltage start control threshold: ThresholdOverVOn, coefficient -3. Data source: via preset parameters.

[0041] Overvoltage start control threshold increment: ThresholdOverVOnAdd, unit V, coefficient -1. Data source: via preset parameters.

[0042] Overvoltage active power regulation granularity ratio: OverVAdjRate, in percentages. Data source: via preset parameters.

[0043] Overvoltage reactive power regulation granularity ratio: OverVAdjVarRate, in percentage. Data source: via preset parameters.

[0044] Maximum number of cycles for overvoltage reactive power regulation: OverVAdjVarTurn, unit of count. Data source: via preset parameters.

[0045] Overvoltage settling time: OverVSteadyTime, in minutes. Data source: via preset parameters.

[0046] Over-power settling time: OverPSteadyTime, in minutes. Data source: via preset parameters.

[0047] Algorithm Introduction Since the main problems addressed by this invention are reverse overload and distributed photovoltaic (PV) overvoltage, it involves regulating the active and reactive power output of the distributed PV system. When a reverse overload occurs, it is eliminated by reducing the active power output of the distributed PV system. When a distributed PV overvoltage occurs, the voltage of the distributed PV system is preferentially reduced by decreasing the reactive power output (when reactive power is set < 0, the PV inverter outputs inductive reactive power). If overvoltage persists even after the reactive power has been reduced to its minimum value, the voltage of the distributed PV system is further reduced by decreasing the active power output of the distributed PV system.

[0048] like Figure 1 The diagram shows the main flow of the overall flexible control algorithm, including: (1) Trigger condition judgment: First, determine whether the preset data collection period has been reached.

[0049] (2) Inverter data acquisition verification: If the acquisition cycle is reached, check whether the inverter data acquisition is completed. If the acquisition timeout or no data is read, return to re-acquire; if the acquisition is completed, read the cross-acquisition data (inverters in fault state do not participate in subsequent control).

[0050] (3) The module executes and updates data judgments sequentially: Enter the "Reverse Overload Judgment and Processing Module" to determine whether all data of the inverter needs to be updated; if not, proceed to the next module.

[0051] Enter the "Inverter Overvoltage Power Limit Judgment and Processing Module" to determine whether all inverter data needs to be updated; if not, proceed to the next module.

[0052] Enter the "Inverter Overvoltage Power Limit Removal Judgment and Processing Module" to determine whether all inverter data needs to be updated; if not, proceed to the next module.

[0053] Enter the "Inverter Power Limit Removal Judgment and Processing Module" to determine whether all inverter data needs to be updated.

[0054] (4) Closed-loop process: Regardless of whether the judgment result of each module needs to update the data, it returns to the "judgment whether the collection cycle has been reached" step to form a loop; and as long as any module has performed the control operation, all data of the inverter needs to be updated again.

[0055] It should be noted that the inverter in the flowchart can be considered equivalent to distributed photovoltaics.

[0056] The power generation of distributed photovoltaic (PV) is actually the active power output of distributed PV.

[0057] The flexible control algorithm provided by this invention includes the design of the following six parts: 1. Data Collection Periodically collect parameters (cross-collection data) of the distribution area, including but not limited to (total active power of the distribution area, transformer capacity, primary and secondary values ​​of CT and PT, etc.) and operating parameters of distributed photovoltaic, including but not limited to (active power, reactive power, power factor, real-time voltage, operating status, fault status, current load limit value, etc.).

[0058] Using the transformer area parameters and preset parameters, the following can be calculated: totVarMax = Load * ThresholdMaxRate.

[0059] totVarTargetMin = Load * ThresholdTargetMinRate.

[0060] totVarTargetMax= Load * ThresholdTargetMaxRate.

[0061] 2. Based on the reverse overload judgment and processing module, the process of the reverse overload judgment and processing module is as follows: Figure 2 As shown: (1) Reverse heavy overload identification: First, determine whether there is a reverse heavy overload in the transformer area (judgment condition: -1 × total active power of the transformer area (totW) > maximum active power threshold of the transformer area (totVarMax)).

[0062] (2) No abnormal branch: If there is no reverse overload, return "No need to update all data of the inverter" and proceed to the next module.

[0063] (3) There are abnormal branches: Select adjustable inverters (troubleshooting devices that are faulty or cannot reduce power).

[0064] If no adjustable inverter exists, return "No need to update all inverter data".

[0065] If an adjustable inverter exists, calculate the current total power generation of the adjustable inverter (sumCurrPower), and calculate the percentage reduction of the current power generation based on the expected adjustable power value (powerOffsetMaxControl) (|powerOffsetMaxControl| / sumCurrPower).

[0066] Poll each adjustable inverter and calculate the reduced active power value (reduction percentage × current generating power) and the new active power limit value (current generating power - reduced active power value) for that inverter in turn.

[0067] (4) Control and feedback: Generate and issue control strategies, and return "All data of the inverter needs to be updated".

[0068] The following is about Figure 2 Additional notes: ① Determine if there is a reverse overload.

[0069] If -1*totW > totVarMax, it represents a reverse overload.

[0070] ② When a reverse overload occurs, record the time of occurrence of the reverse overload. Calculate the active power limit value of the distributed photovoltaic equipment and issue the control strategy accordingly.

[0071] powerOffsetMaxControl = ACDataObj.totVarTargetMin + ACDataObj.totW.

[0072] sumCurrPower = Current total power generation of all distributed photovoltaic systems.

[0073] Current power generation reduction percentage = powerOffsetMaxControl / sumCurrPower. Unit: %, coefficient: -1.

[0074] In summary, the active power limit values ​​for distributed photovoltaic (PV) equipment are as follows: Figure 2The calculations shown are as follows.

[0075] ③ If there is no reverse overload or no adjustable distributed photovoltaic equipment (cannot set a lower active power limit value), the process will proceed to step 3.

[0076] 3. Based on the distributed photovoltaic overvoltage power limitation judgment and processing module, the inverter overvoltage power limitation judgment and processing module process is as follows: Figure 3 As shown: (1) Overvoltage inverter identification: First, determine whether there is an overvoltage inverter (judgment condition: photovoltaic voltage ≥ Vmax, Vmax is the maximum value of "overvoltage start control threshold voltage conversion" and "threshold value increment + maximum output voltage of the transformer area").

[0077] (2) No abnormal branch: If there is no overvoltage inverter, return "No need to update all data of inverter" and proceed to the next module.

[0078] (3) There are abnormal branches: Screen overvoltage inverters with adjustable power (excluding faulty or unadjustable devices), and determine if there are overvoltage inverters with adjustable reactive / active power and whether this is the first time this check is performed. If neither exists, return "No need to update all inverter data"; if they exist, prioritize polling overvoltage inverters with adjustable reactive power, then poll overvoltage inverters with adjustable active power.

[0079] Calculate the power limit value: New reactive power limit value = Rated reactive power × (Current reactive power / Rated reactive power - 5% (configurable)); New active power limit value = Rated active power × (Current active power / Rated active power - 5% (configurable)).

[0080] Threshold verification: If the new reactive power limit value is less than or equal to the minimum allowable reactive power output under overvoltage, then set it as the minimum allowable value; the same applies to the new active power limit value.

[0081] Generate corresponding control commands and issue control commands and read data from the controllable overvoltage inverter in parallel.

[0082] (4) Secondary verification and feedback: After the inverter data acquisition is completed, read the collected data and determine whether there is a reverse overload. If there is a reverse overload or regulation has been performed, return "All inverter data needs to be updated".

[0083] The following is about Figure 3 Additional notes: ① Determine if there is overvoltage.

[0084] Vmax1 = ThresholdOverVOn * 0.001 * 220.0, Vmax2 = ThresholdOverVOnAdd + phV_Max.

[0085] Vmax = the maximum value between Vmax1 and Vmax2.

[0086] If the voltage of a distributed photovoltaic system is greater than or equal to Vmax, it indicates overvoltage.

[0087] ② When a distributed photovoltaic system experiences overvoltage, record the time when the overvoltage occurs.

[0088] ③ For power limiting of distributed photovoltaic systems under overvoltage, priority should be given to limiting reactive power. If limiting reactive power alone cannot solve the overvoltage situation, then active power will be limited.

[0089] ④ New reactive power limit for distributed photovoltaic (PV) = Rated reactive power of distributed PV * Current reactive power of distributed PV / Rated reactive power of distributed PV - OverVAdjVarRate.

[0090] ⑤ New active power limit for distributed photovoltaic power = Rated active power of distributed photovoltaic power * Current active power of distributed photovoltaic power / Rated active power of distributed photovoltaic power - OverVAdjRate.

[0091] ⑥ After calculating the active / reactive power limits of distributed photovoltaic power, the control strategy is issued, and data is collected and analyzed immediately after issuance.

[0092] ⑦ If there is no overvoltage distributed photovoltaic or no adjustable overvoltage distributed photovoltaic (cannot set a lower active / reactive power limit value, or has reached the maximum cycle limit of overvoltage reactive power adjustment), then proceed to step 4 for judgment.

[0093] 4. Based on the overvoltage power limitation release judgment and processing module for distributed photovoltaic equipment, the process of the inverter overvoltage power limitation release judgment and processing module is as follows: Figure 4 As shown: (1) Pre-judgment of the release condition: First, determine whether the load condition of the transformer area meets the requirements for releasing the power limit (judgment condition: -1×totW<minimum threshold of active power control target of transformer area (totVarTargetMin)).

[0094] (2) Branch where the release condition is not met: If the condition is not met, return "No need to update all data of the inverter".

[0095] (3) Satisfaction of the release condition branch: Determine whether there is an inverter with "overvoltage and power limited" (current voltage < Vmax and in the power limit state). If not, return "There is no need to update all inverter data".

[0096] Screen the target inverters that can be regulated, and determine whether there are devices that can regulate reactive power / active power and whether it is the first judgment. If both do not exist, return "There is no need to update all inverter data"; if they exist, preferentially poll the devices that can regulate reactive power, and then poll the devices that can regulate active power.

[0097] Calculate the power limit value after release: New reactive power limit value = rated reactive power × (original reactive power limit percentage + 5% (can be set)); New active power limit value = rated active power × (original active power limit percentage + 5% (can be set)).

[0098] Threshold verification: If the new power limit value > rated power, set it to the rated power and generate the corresponding regulation command.

[0099] Parallelly issue the regulation command and read the data of the target inverter.

[0100] (4) Secondary verification and feedback: After the data acquisition is completed, read the AC sampling data and determine whether there is reverse overload. If there is reverse overload or the regulation has been executed, return "There is a need to update all inverter data".

[0101] The following is the supplementary explanation for Figure 4 : ① Determine whether the load condition of the transformer area meets the requirement of releasing the inverter power limit.

[0102] If -1*totW < totVarTargetMin, it means that the requirement of releasing the inverter power limit is met.

[0103] ② Determine whether there is overvoltage.

[0104] Vmax1 = ThresholdOverVOn * 0.001 * 220.0, Vmax2 = ThresholdOverVOnAdd + phV_Max.

[0105] Vmax = the maximum value between Vmax1 and Vmax2.

[0106] If the voltage of the distributed PV is less than Vmax, it means there is no overvoltage.

[0107] ③For the release of the power limit of overvoltage distributed PV, the reactive power limit is released first. If there is no overvoltage and reverse overload during the release of the reactive power limit, the active power limit will be released continuously.

[0108] ④The new reactive power limit value of distributed PV = rated reactive power of distributed PV * (original reactive power limit value of distributed PV + OverVAdjVarRate).

[0109] ⑤The new active power limit value of distributed PV = rated active power of distributed PV * (original active power limit value of distributed PV + OverVAdjRate).

[0110] ⑥Calculate the time when the distributed PV equipment with overvoltage operates at normal voltage. When this time exceeds 1 OverVSteadyTime, calculate the active / reactive power limit value of the distributed PV, and issue the control strategy. Immediately after issuing, data collection is performed, and the data is analyzed and processed.

[0111] ⑦If there is no distributed PV that needs to release the active / reactive power limit due to overvoltage or there is no distributed PV that needs to be regulated to release the active / reactive power limit due to overvoltage (unable to set a higher active / reactive power limit value), it will enter the judgment in step 5.

[0112] 5. Based on the active power limit release judgment and processing module for distributed PV equipment, the inverter power limit release judgment and processing module process is as Figure 5 shown: (1) Steady time verification: First, judge whether the distribution area has been operating in the "no reverse overload" state for more than 1 preset over-power steady time (OverPSteadyTime).

[0113] (2) Branch for not reaching the steady time: If not exceeded, return "Do not need to update all inverter data".

[0114] (3) Branch for reaching the steady time: Judge whether the load condition of the distribution area meets the power limit release (judgment condition: -1×totW<totVarTargetMin). If not met, return "Do not need to update all inverter data".

[0115] Screen the adjustable inverters (exclude equipment with overvoltage, faults or rated output). If there are no adjustable inverters, return "Do not need to update all inverter data".

[0116] Calculate the current total power generation of the adjustable inverter (sumCurrPower), and calculate the percentage increase in the current power generation based on the desired adjustment power value (powerOffsetMaxControl) (powerOffsetMaxControl / sumCurrPower).

[0117] Poll each adjustable inverter, and calculate the increased active power value of the inverter in turn (percentage increase × current power generation) and the new active power limit value (original power limit value + increased active power value).

[0118] (4)Regulation and feedback: Generate and issue a regulation strategy, and return "All data of the inverter needs to be updated".

[0119] The following is the supplementary note for Figure 5 : ① Calculate the running time of the distribution area under normal load conditions (without reverse overload). When this time exceeds 1 OverPSteadyTime, it will be judged whether the load condition of the distribution area meets the requirement of解除逆变器功率限制.

[0120] If -1 * totW < totVarTargetMin, it means that the requirement of解除逆变器功率限制 is met.

[0121] ② When the requirement of解除逆变器功率限制 is met, calculate the active power limit value of the distributed photovoltaic equipment for解除分布式光伏有功功率限制. When calculating, exclude the distributed photovoltaic with overvoltage and calculate the remaining distributed photovoltaic.

[0122] powerOffsetMaxControl = ACDataObj.totVarTargetMax + ACDataObj.totW.

[0123] sumCurrPower = The current total power generation of all distributed photovoltaics with normal voltage.

[0124] The percentage increase in the current power generation = powerOffsetMaxControl / sumCurrPower. Unit: %, coefficient -1.

[0125] To sum up, the active power limit value of the distributed photovoltaic equipment is calculated as Figure 5 shown.

[0126] ③ If there is no more than 1 OverPSteadyTime or no controllable distributed photovoltaic (distributed photovoltaics are already at rated active power output or distributed photovoltaics are in an overvoltage state), then proceed to step 6 for judgment.

[0127] 6. Determine whether immediate data collection is necessary to initiate a new round of flexible control algorithm: Once a control strategy has been issued, data collection must be proactively conducted to implement a new round of flexible control algorithms. This approach improves the timeliness of the algorithm.

[0128] Note: The priority of the flexible control algorithm from high to low is as follows: reverse heavy overload judgment and processing module > distributed photovoltaic equipment overvoltage power limit judgment and processing module > distributed photovoltaic equipment overvoltage power limit release judgment and processing module > distributed photovoltaic equipment active power limit release judgment and processing module. The purpose of this design is to prioritize the handling of situations with higher risk levels and improve the sensitivity and reliability of the algorithm.

[0129] The key features of this invention include: 1. Real-time Data Monitoring and Acquisition: To ensure the accuracy and real-time nature of transformer area load status and distributed photovoltaic (PV) operating parameters, this invention sets up a configurable periodic parameter acquisition task to periodically collect transformer area load status and distributed PV operating parameters. Different periodic parameters can be configured according to the connection status of distributed PV in different transformer areas to ensure the accuracy and real-time nature of transformer area load status and distributed PV operating parameters.

[0130] 2. Analysis of transformer area load and distributed photovoltaic operation status: A comprehensive analysis is conducted on the collected transformer area load and distributed photovoltaic operation parameters. It is highly sensitive to reverse overload of transformer areas and accurately identifies reverse overload conditions, overvoltage conditions, and fault conditions of distributed photovoltaic equipment.

[0131] 3. Flexible and accurate control strategies: When a transformer substation experiences reverse overload or distributed photovoltaic (PV) overvoltage, the control strategy must be tailored to the substation's load condition and the operating status of the distributed PV system. Since reverse overload poses the greatest risk, it will be addressed first. Once the reverse overload is resolved, the distributed PV overvoltage will be addressed. After the abnormal situation is resolved, further control measures will be implemented based on the substation's load condition and the distributed PV system's operating status to ensure maximum active power output from the distributed PV system. Furthermore, a feedback mechanism will be implemented throughout the control process to minimize unnecessary adjustments and ensure the flexibility and accuracy of the control strategy.

[0132] Its technical effects include at least: 1. Improve the safety and stability of the power grid and photovoltaic system: Real-time monitoring of reverse overload conditions in the distribution area and overvoltage conditions of distributed photovoltaic equipment, with timely adjustments made in case of abnormalities. This mechanism effectively avoids reverse overload conditions in the distribution area and prevents damage to distributed photovoltaic equipment due to overvoltage.

[0133] 2. Reduced operating and maintenance costs: By monitoring and controlling the overvoltage status of distributed photovoltaic (PV) equipment, the occurrence of malfunctions and damage can be effectively reduced. Maintenance personnel can also remotely troubleshoot and detect faults in on-site distributed PV equipment and perform maintenance, reducing time costs and eliminating the need for additional hardware, thus improving economic efficiency.

[0134] 3. In line with sustainable development goals: By monitoring and regulating reverse overload and overvoltage of distributed photovoltaic (PV) equipment, and when the load conditions in the distribution area and the operating status of the distributed PV system permit, the distributed PV equipment will be allowed to output maximum active power. This maximizes the utilization of solar energy, reduces reliance on traditional energy sources, and minimizes greenhouse gas emissions while ensuring the safety and stability of the power grid and the PV system.

[0135] 4. Ensure fairness for distributed photovoltaic users: When flexible regulation is required, each distributed photovoltaic device will be fully considered and unified regulation will be implemented.

[0136] It should be further noted that the current control strategy for distributed photovoltaic (PV) systems in this invention only achieves active / reactive power regulation. Further control terms, such as power factor, can be added to improve the algorithm and provide more comprehensive control over distributed PV systems. However, adding control terms increases the hardware requirements for distributed PV equipment, necessitating equipment support for the control terms. It also increases the complexity of the algorithm, making its design more difficult and increasing the risk of system instability. Furthermore, to meet more control needs, it requires collecting more operating parameters from distributed PV equipment, increasing the resource consumption of data acquisition channels.

[0137] Based on the same inventive concept, this invention also provides a computer device, comprising: one or more processors, and a memory for storing one or more computer programs; the program includes program instructions, and the processor executes the program instructions stored in the memory. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, used to implement one or more instructions, specifically for loading and executing one or more instructions stored in a computer storage medium to implement the above-described method.

[0138] It should be further explained that, based on the same inventive concept, the present invention also provides a computer storage medium storing a computer program, which, when executed by a processor, performs the above-described method. This storage medium can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0139] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0140] The foregoing has shown and described the basic principles, main features, and advantages of this disclosure. Those skilled in the art should understand that this disclosure is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this disclosure. Various changes and modifications can be made to this disclosure without departing from its spirit and scope, and all such changes and modifications fall within the scope of this disclosure as claimed.

[0141] This invention is not limited to the preferred embodiment described above. Anyone inspired by this invention can derive other various forms of methods for regulating and controlling reverse overload and overvoltage in active power distribution areas. All equivalent variations and modifications made within the scope of the claims of this invention shall fall within the scope of this invention.

Claims

1. A method for regulating and mitigating reverse overload and overvoltage in an active power distribution area, wherein the distribution area is connected to multiple distributed photovoltaic inverters, characterized in that, include: Based on the grid connection scale and operating characteristics of the distributed photovoltaic inverters in the distribution area, the data collection cycle is configured to periodically collect the operating parameters of the distribution area and the operating parameters of each distributed photovoltaic inverter. The operating parameters of the distribution area include at least the transformer capacity, total active power, and maximum output voltage; the operating parameters of the distributed photovoltaic inverter include at least the active power, reactive power, real-time voltage, and operating status. Tiered mode control: Control modes are activated in order of priority, from highest to lowest: reverse overload control mode, overvoltage control mode, and power recovery control mode. Reverse overload control mode: When the absolute value of the reverse of the total active power of the distribution area is greater than the first power threshold determined by the product of the distribution transformer capacity and the first preset proportional coefficient, the goal is to reduce the reverse power to the second power threshold determined by the product of the distribution transformer capacity and the second preset proportional coefficient. Based on the current total power generation of all controllable inverters, a unified power adjustment ratio is calculated, the active power limit value of each inverter is determined, and a control command is issued. Overvoltage control mode: When the real-time inverter voltage is greater than or equal to the overvoltage threshold value determined by the maximum value among the conversion value of the preset overvoltage start threshold and the normal voltage reference value, and the superposition value of the maximum output voltage of the transformer area and the preset voltage increment, the reactive power is preferentially reduced by the preset reactive power adjustment granularity. If the voltage is still too high, the active power will be reduced by the preset active power adjustment granularity and a control command will be issued. Power recovery control mode: When the duration of no reverse heavy overload in the distribution area exceeds the preset overpower stabilization time and the duration of no overvoltage in the inverter exceeds the preset overvoltage stabilization time, the overvoltage power limit is first lifted, then the overvoltage inverter is excluded. The unified power adjustment ratio is calculated based on the maximum threshold of the active power control target determined by the product of the distribution transformer capacity and the third preset proportional coefficient. The active power limit release value of the normal inverter is determined and the instruction is issued. Each time a control command is issued, a new round of operating parameter collection is immediately triggered, and a tiered control mode is initiated to form a control closed loop.

2. The method for regulating and controlling reverse heavy overload and overvoltage in an active power distribution area according to claim 1, characterized in that: The periodic data collection specifically includes: parallel reading of data from all normally operating distributed photovoltaic inverters and AC data collected from the distribution area, excluding distributed photovoltaic inverters in a faulty state; the collection period is a parameter dynamically configured based on the number of distributed photovoltaic inverters connected to the distribution area and the frequency of load fluctuations in the distribution area.

3. The method for regulating and controlling reverse overload and overvoltage in an active power distribution area according to claim 1, characterized in that: In the reverse overload control mode, the calculation method of the unified power adjustment ratio is: (second power threshold + total active power of the distribution area) ÷ current total power generation of all adjustable inverters; the adjustable inverter is a distributed photovoltaic inverter that is in normal operating condition and can be set with a lower active power limit value, and the active power limit value of each inverter is determined based on the unified power adjustment ratio.

4. The method for regulating and controlling reverse heavy overload and overvoltage in an active power distribution area according to claim 1, characterized in that: In the overvoltage control mode, the conversion method between the preset overvoltage start threshold and the conventional voltage reference value is: preset overvoltage start threshold × 0.001 × conventional voltage reference value; the reduction of reactive power specifically means reducing the inductive reactive power output of the inverter, and the inductive reactive power is represented by a negative value; and the number of reactive power adjustments does not exceed the preset maximum number of overvoltage reactive power adjustments.

5. The method for regulating and controlling reverse overload and overvoltage in an active power distribution area according to claim 1, characterized in that: In the power recovery control mode, the calculation method of the unified power adjustment ratio is: (maximum threshold of active power control target + total active power of the distribution area) ÷ current total power generation of all normal inverters; the normal inverter is a distributed photovoltaic inverter with normal operating status and real-time voltage below the overvoltage threshold. The active power limit release value of each inverter is determined based on the unified power adjustment ratio, and the limit release value does not exceed the rated active power of the inverter.

6. The method for regulating and controlling reverse overload and overvoltage in an active power distribution area according to claim 1, characterized in that: The real-time closed-loop feedback specifically includes: after the control command is issued, a new round of data acquisition is immediately started. After the acquisition is completed, it is first determined whether there is still reverse heavy overload in the transformer area, and then the overvoltage status and power recovery conditions are determined in turn. The corresponding control mode is executed in the original priority order until no control command needs to be issued.

7. The method for regulating and controlling reverse heavy overload and overvoltage in an active power distribution area according to claim 1, characterized in that: The unified power adjustment ratio applies uniformly to all adjustable inverters or normal inverters, ensuring that the power adjustment range of each distributed photovoltaic inverter is proportional to its current power generation.

8. The method for regulating and controlling reverse heavy overload and overvoltage in an active power distribution area according to claim 1, characterized in that: The first preset proportional coefficient, the second preset proportional coefficient, the third preset proportional coefficient, the preset overvoltage start threshold, the preset voltage increment, the preset reactive power regulation granularity, the preset active power regulation granularity, the preset overpower stabilization time, and the preset overvoltage stabilization time are all configurable parameters preset based on the distribution transformer capacity, the total installed capacity of distributed photovoltaic power and the grid operation standards.

9. A coordinated regulation and control system for reverse heavy overload and overvoltage in an active power distribution area, wherein the distribution area is connected to multiple distributed photovoltaic inverters, characterized in that, include: The data acquisition module is used to configure the acquisition cycle according to the access scale and operating characteristics of the distributed photovoltaic inverters in the distribution area, and to periodically acquire the operating parameters of the distribution area and the operating parameters of each distributed photovoltaic inverter; the operating parameters of the distribution area include at least the transformer capacity, total active power, and maximum output voltage, and the operating parameters of the distributed photovoltaic inverters include at least the active power, reactive power, real-time voltage, and operating status; Hierarchical control module: used to activate control modes in order of priority, from high to low priority: reverse heavy overload control mode, overvoltage control mode, and power recovery control mode, and can generate and issue corresponding control commands; Closed-loop feedback module: After each control command is issued, it immediately triggers the adaptation acquisition module to reacquire operating parameters and drives the hierarchical control module to start a new round of hierarchical mode control, forming a flexible and collaborative control closed loop.

10. A computer device, comprising a processor and a storage medium, characterized in that, The storage medium stores a computer program, and when the processor executes the computer program, it implements the method described in any one of claims 1-8.

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