A distributed photovoltaic output regulation method and system

Abstract

The application relates to the technical field of power regulation, and discloses a distributed photovoltaic output regulation method and system. Real-time operation parameters of photovoltaic inverters in a target transformer area and grid node voltages of a low-voltage distribution network are periodically monitored, a preset voltage out-of-limit threshold is combined, whether a voltage out-of-limit event occurs in the target transformer area is judged according to a differentiated judgment rule, and a voltage out-of-limit type corresponding to the voltage out-of-limit event is marked. After the out-of-limit event occurs, a layered step regulation strategy is generated according to the real-time operation parameters and the voltage out-of-limit type, and the photovoltaic inverters are controlled to be executed, so that the grid node voltages are updated. When the updated voltage data satisfies a double-dimension preset stable condition, an instruction of stopping regulation is issued to the photovoltaic inverters, and a regulation end event is generated. Without additionally configuring a large number of traditional regulation devices, accurate voltage regulation can be completed only through the regulation capacity of the photovoltaic inverters, and life loss caused by frequent operation of the devices is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of power regulation technology, and in particular to a method and system for regulating distributed photovoltaic power output. Background Technology

[0002] With the large-scale integration of distributed photovoltaic (PV) power, the problem of voltage exceeding limits in low-voltage distribution networks is becoming increasingly prominent. Traditional voltage regulation methods, such as switching capacitors and regulating transformer taps, have slow response times and short lifespans, making them difficult to adapt to rapid fluctuations in PV output. While directly reducing PV active power output can quickly suppress overvoltage, it results in wasted power generation. Although existing technologies utilize the reactive power regulation capabilities of PV inverters for voltage control, most employ simple fixed-step regulation, lacking precise perception of the grid's dynamic characteristics and collaborative optimization among inverters, leading to low regulation efficiency and poor regulation accuracy.

[0003] Therefore, improving the efficiency and accuracy of power output regulation in distributed photovoltaic systems has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a method and system for regulating the output of distributed photovoltaic power, addressing the problem of improving the efficiency and accuracy of regulating the output of distributed photovoltaic power.

[0005] To address the aforementioned technical problems, the first aspect of this invention provides a method for regulating distributed photovoltaic power output, comprising: Periodically monitor the output parameters of the target transformer area; the output parameters include the real-time operating parameters of the photovoltaic inverter and the grid node voltage of the low-voltage distribution network; Based on the grid node voltage and the preset voltage over-limit threshold, determine whether a voltage over-limit event has occurred in the target transformer area according to the differentiated judgment rules, and mark the voltage over-limit type corresponding to the voltage over-limit event; Based on the real-time operating parameters and the voltage over-limit type, a hierarchical step-by-step control strategy is generated and the photovoltaic inverter is controlled to execute it in order to update the output parameters; When the updated output parameters meet the dual-dimensional preset stability conditions, a control command is issued to the photovoltaic inverter, and a control end event is generated.

[0006] As one preferred embodiment, the grid node voltage includes a first-phase voltage, a second-phase voltage, and a third-phase voltage; the preset voltage over-limit threshold includes an upper voltage over-limit threshold and a lower voltage over-limit threshold; wherein... The process of determining whether a voltage over-limit event has occurred in the target transformer area based on the grid node voltage and a preset voltage over-limit threshold, according to a differentiated judgment rule, and marking the voltage over-limit type corresponding to the voltage over-limit event, includes: When the voltage of the first phase, the voltage of the second phase, or the voltage of the third phase exceeds the voltage over-limit threshold, it is determined that the voltage over-limit event has occurred, and the voltage over-limit type corresponding to the voltage over-limit event is marked as overvoltage over-limit. When the first phase voltage, the second phase voltage, and the third phase voltage are all less than the voltage lower limit threshold, it is determined that the voltage limit event has occurred, and the voltage limit type corresponding to the voltage limit event is marked as low voltage lower limit.

[0007] As one preferred embodiment, the real-time operating parameters include real-time reactive power data; wherein, The step of generating a hierarchical, step-by-step control strategy based on the real-time operating parameters and the voltage over-limit type, and controlling the photovoltaic inverter to execute it, includes: When the voltage over-limit type is the overvoltage over-limit and the real-time reactive power data is greater than the preset reactive power threshold, primary regulation is triggered to generate a first-level regulation command to control the photovoltaic inverter to adjust its own reactive power to zero. The grid node voltage after reactive power adjustment is collected as the first voltage data. When the voltage over-limit event occurs in the target transformer area based on the first voltage data, secondary regulation is triggered to generate a second-level regulation command to control the photovoltaic inverter to adjust its own active power according to the preset active power adjustment rules. The grid node voltage after the active power adjustment is collected as the second voltage data, and the judgment step of the voltage over-limit event and the active power adjustment step of the photovoltaic inverter are iteratively executed based on the second voltage data until the voltage over-limit event is eliminated.

[0008] As one preferred embodiment, the method further includes: when the over-limit type is the overvoltage over-limit and the real-time reactive power data is equal to zero, directly triggering the secondary control and issuing the secondary control command to the photovoltaic inverter.

[0009] As one preferred embodiment, the preset active power adjustment rule is configured to adjust the power percentage of the active power according to a preset active power amplitude, and / or to adjust the value of the active power according to a preset active power absolute value.

[0010] As one preferred embodiment, the real-time operating parameters include real-time active power data and rated power data; wherein, The step of generating a hierarchical, step-by-step control strategy based on the real-time operating parameters and the voltage over-limit type, and controlling the photovoltaic inverter to execute it, includes: When the voltage over-limit type is the low voltage over-limit and the real-time active power data is less than the rated power data, primary regulation is triggered to generate a third-level regulation command to control the photovoltaic inverter to adjust its own active power to the rated power data. The grid node voltage after the active power adjustment is collected as the third voltage data. When the voltage over-limit event occurs in the target transformer area based on the third voltage data, the secondary regulation is triggered to generate a fourth-level regulation command to control the photovoltaic inverter to adjust its own reactive power according to the preset reactive power adjustment rules. The grid node voltage after reactive power adjustment is collected as the fourth voltage data, and the judgment step of the voltage over-limit event and the reactive power adjustment step of the photovoltaic inverter are iteratively executed based on the fourth voltage data until the voltage over-limit event is eliminated.

[0011] As one preferred embodiment, the method further includes: when the over-limit type is the low voltage over-limit and the real-time active power data is equal to the rated power data, directly triggering the secondary control and issuing the fourth-level control command to the photovoltaic inverter.

[0012] As one preferred embodiment, the preset reactive power adjustment rule is configured to adjust the power percentage of the reactive power according to a preset reactive power amplitude, and / or to adjust the value of the reactive power according to a preset reactive power absolute value.

[0013] As one preferred embodiment, the step of issuing a control command to the photovoltaic inverter when the updated output parameters meet the dual-dimensional preset stability conditions includes: When the updated grid node voltage continues to operate within the preset voltage over-limit threshold for a preset number of cycles, and the updated real-time operating parameters recover to the preset output benchmark corresponding to the voltage over-limit type, a control command to stop adjustment is issued to the photovoltaic inverter; wherein, the preset output benchmark corresponding to the overvoltage over-limit is that the active power of the photovoltaic inverter is equal to the rated power data; the preset output benchmark corresponding to the low voltage over-limit is that the reactive power of the photovoltaic inverter is equal to zero.

[0014] A second aspect of this invention provides a distributed photovoltaic power output control system, comprising a fusion terminal, a photovoltaic inverter, a photovoltaic micro-circuit, and a communication conversion interface; wherein, The fusion terminal is used to execute the distributed photovoltaic power output control method as described in the first aspect; The photovoltaic micro-circuit is connected to the photovoltaic inverter and the fusion terminal respectively, and is used to transmit the real-time operating parameters of the photovoltaic inverter and the grid node voltage of the low-voltage distribution network to the fusion terminal, and to provide circuit continuity protection when the low-voltage distribution network has a circuit abnormality. The photovoltaic inverter is connected to the photovoltaic micro-circuit via the communication conversion interface, and is used to receive and execute the control commands sent by the fusion terminal.

[0015] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows: By monitoring the output parameters of the target distribution area in real time and setting differentiated over-limit judgment rules, the real-time perception of the distribution network operation status can be achieved, enabling rapid response to voltage over-limit problems caused by distributed photovoltaic output fluctuations. Compared with the traditional solution that relies on capacitor bank switching and on-load tap-changing transformer voltage regulation, this invention does not require the additional configuration of a large number of traditional regulation equipment. Voltage regulation can be completed solely through the active and reactive power regulation capabilities of the photovoltaic inverter itself, effectively avoiding lifespan loss caused by frequent equipment operation. The hierarchical step-by-step regulation strategy is used to regulate the photovoltaic inverter in stages, avoiding simultaneous and batch disconnection of photovoltaic inverters from the grid due to sudden voltage rises. This minimizes the waste of photovoltaic power generation resources and significantly improves the utilization rate of photovoltaic power generation. It also improves the efficiency and accuracy of output regulation for distributed photovoltaics, and prevents drastic fluctuations in grid power or even power outages caused by chain reactions, thereby improving the safety and stability of the power grid. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of a distributed photovoltaic power output regulation method provided in a certain embodiment of the present invention; Figure 2 This is a structural diagram of a distributed photovoltaic power output regulation system provided in a certain embodiment of the present invention; Figure label: Among them, 201 is the integrated terminal; 202 is the photovoltaic micro-circuit; 203 is the photovoltaic inverter; and 204 is the communication conversion interface. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0021] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is merely for describing specific embodiments and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0022] In one embodiment, such as Figure 1 As shown, the first aspect of the present invention provides a method for regulating distributed photovoltaic power output, comprising: S1. Periodically monitor the output parameters of the target transformer area; Specifically, the target distribution area in this invention refers to a specific low-voltage power distribution area requiring distributed photovoltaic (PV) output regulation. This area can be divided according to the power distribution topology of the actual application scenario, such as defining a target distribution area as the power supply range covered by a single distribution transformer. The monitoring data period can be set via a configuration file, with a default period of 5 seconds. Maintenance personnel can adjust the period parameter based on the frequency of grid voltage fluctuations; for example, the period can be shortened to 2 seconds during periods of significant PV output fluctuations to improve response speed. The output parameters include the real-time operating parameters of the photovoltaic inverter and the grid node voltage of the low-voltage distribution network. The real-time operating parameters include real-time reactive power data (reactive power exchanged between the photovoltaic inverter and the grid, in kilovars (kVar). When the inverter absorbs reactive power, the reactive power is positive; when it outputs reactive power, the reactive power is negative. In this embodiment, the reactive power is an algebraic value), real-time active power data (the actual active power output by the photovoltaic inverter, in kilowatts (kW), and rated power data (the maximum active power that the photovoltaic inverter can provide under the current operating conditions). The grid node voltage refers to the voltage value at the grid connection point of the photovoltaic inverter, including the first phase voltage (phase A), the second phase voltage (phase B), and the third phase voltage (phase C), in volts (V).

[0023] S2. Based on the grid node voltage and the preset voltage over-limit threshold, determine whether a voltage over-limit event has occurred in the target distribution area according to the differentiated judgment rules, and mark the voltage over-limit type corresponding to the voltage over-limit event; wherein, the preset voltage over-limit threshold includes an upper voltage over-limit threshold and a lower voltage over-limit threshold; the default value of the upper voltage over-limit threshold is 235V, and the default value of the lower voltage over-limit threshold is 198V. These two thresholds can be modified through threshold parameters in the configuration file to adapt to the voltage standard requirements of low-voltage distribution networks in different regions. For example, in some areas where the allowable voltage range of the grid is narrow, the upper voltage over-limit threshold can be adjusted to 232V, and the lower voltage over-limit threshold can be adjusted to 200V.

[0024] In one embodiment, step S2 includes: When the voltage of the first phase, the voltage of the second phase, or the voltage of the third phase exceeds the voltage over-limit threshold, it is determined that the voltage over-limit event has occurred, and the voltage over-limit type corresponding to the voltage over-limit event is marked as overvoltage over-limit. When the first phase voltage, the second phase voltage, and the third phase voltage are all less than the voltage lower limit threshold, it is determined that the voltage limit event has occurred, and the voltage limit type corresponding to the voltage limit event is marked as low voltage lower limit.

[0025] Specifically, if any phase voltage at a grid-connected point exceeds the upper voltage limit threshold, a voltage over-limit event is identified in the target distribution area, and the event type is marked as overvoltage exceeding the upper limit. If all three phase voltages at a grid-connected point are less than the lower voltage limit threshold, a voltage over-limit event is identified in the target distribution area, and the event type is marked as undervoltage exceeding the lower limit. If all three phase voltages are less than or equal to the upper voltage limit threshold, and at least one phase voltage is greater than or equal to the lower voltage limit threshold, then no voltage over-limit event is identified.

[0026] This invention, through comprehensive monitoring and classification of three-phase voltages, avoids malfunctions caused by misjudgments of single-phase signals (such as instantaneous fluctuations in a single phase) and accurately identifies different types of voltage limit exceedance scenarios. Specifically, a low-voltage lower limit event requires all three-phase voltages to be below the lower threshold, reflecting an overall insufficient power in the distribution area, necessitating power boosting control across the entire area. Conversely, an overvoltage upper limit event triggers whenever any phase voltage exceeds the upper limit, reflecting excessive power backflow in one or two phases, allowing for targeted control of the photovoltaic inverters on the corresponding phases.

[0027] S3. Based on the real-time operating parameters and the voltage over-limit type, generate a hierarchical step-by-step control strategy and control the photovoltaic inverter to execute it, so as to update the output parameters; In one embodiment, generating a hierarchical step-by-step control strategy based on the real-time operating parameters and the voltage over-limit type, and controlling the photovoltaic inverter to execute it, includes: When the voltage over-limit type is the overvoltage over-limit and the real-time reactive power data is greater than the preset reactive power threshold, primary regulation is triggered to generate a first-level regulation command to control the photovoltaic inverter to adjust its own reactive power to zero. The grid node voltage after reactive power adjustment is collected as the first voltage data. When the voltage over-limit event occurs in the target transformer area based on the first voltage data, secondary regulation is triggered to generate a second-level regulation command to control the photovoltaic inverter to adjust its own active power according to the preset active power adjustment rules. The grid node voltage after the active power adjustment is collected as the second voltage data, and the judgment step of the voltage over-limit event and the active power adjustment step of the photovoltaic inverter are iteratively executed based on the second voltage data until the voltage over-limit event is eliminated.

[0028] Specifically, in the event of a voltage over-limit event occurring in the target distribution area, if the type is overvoltage exceeding the upper limit and the reactive power of the photovoltaic inverter is greater than the preset reactive power threshold of 0, primary control is triggered. A first-level control command is generated and sent to the photovoltaic inverter, so that it adjusts its reactive power to zero according to the first-level control command. Next, the grid node voltage after reactive power adjustment is obtained as the first voltage data. If it is within the preset voltage over-limit threshold, the control is deemed effective, and step S4 is executed to enter the stability confirmation process; if it is not within the preset voltage over-limit threshold (that is, the voltage over-limit event has not been eliminated), the reactive power adjustment is deemed insufficient to solve the overvoltage problem, and secondary control is triggered. A second-level control command is generated and sent to the photovoltaic inverter, so that it adjusts its active power according to the preset active power adjustment rules according to the second-level control command. Subsequently, the grid node voltage after the active power adjustment is collected and used as the second voltage data. The relationship between the second voltage data and the preset voltage over-limit threshold is used to perform the voltage over-limit event judgment step. If the over-limit event still exists, the active power of the photovoltaic inverter is adjusted according to the above adjustment rules. This process is repeated until the voltage over-limit event is eliminated.

[0029] The preset active power adjustment rule is configured to adjust the percentage of active power based on a preset active power amplitude, and / or to adjust the value of active power based on a preset active power absolute value. In other words, the preset active power adjustment rule includes two modes, which can be selected as a single mode or a combination of modes through a configuration file: Percentage adjustment mode: Adjusts the percentage of active power based on a preset active power amplitude. For example, if the active power reduction amplitude is set to 5%, then each time a control command is issued, the current active power will be reduced by 5%. That is, if the current active power is 10kW, it will be reduced to 9.5kW the first time; if the voltage still does not recover, it will be reduced to 9.025kW (95% of 9.5kW) the second time, and so on. Alternatively, in absolute value adjustment mode: the active power is adjusted based on a preset absolute value. For example, if the absolute value for reducing active power is set to 0.5kW, then each time an adjustment command is issued, the current active power will be reduced by 0.5kW. That is, if the current active power is 10kW, it will be reduced to 9.5kW the first time; if the voltage still does not recover, it will be reduced to 9.0kW the second time, and so on. Alternatively, in combined mode: absolute value adjustment can be used first, and then switched to percentage adjustment when the active power drops to a certain threshold to avoid excessive reduction. For example, if the absolute value adjustment step is set to 0.5kW, when the active power drops to 5kW, it will switch to percentage adjustment (5% step) for more precise control. It is important to note that the active power reduction must not be lower than the minimum technical output of the photovoltaic inverter (usually 10% of the rated power). Falling below this value will cause the inverter to shut down. A lower limit protection must be set during the adjustment process. When the active power has dropped to the minimum technical output and the voltage has not recovered, the current output will be maintained and an alarm will be issued.

[0030] Furthermore, when the over-limit type is an overvoltage exceeding the upper limit and the real-time reactive power data is equal to zero, the secondary control is directly triggered, and the secondary control command is issued to the photovoltaic inverter. In other words, when the overvoltage exceeds the upper limit, if the reactive power of the photovoltaic inverter is equal to 0 (i.e., the inverter is already operating at unity power factor), the second control command is directly issued to the photovoltaic inverter without going through the reactive power adjustment step, thereby shortening the control chain and accelerating the response speed.

[0031] In scenarios where overvoltage exceeds the upper limit, this invention employs a layered control strategy of "first adjusting reactive power to zero, then adjusting active power": prioritizing the use of the reactive power regulation capability of the photovoltaic inverter to zero reactive power; only when reactive power regulation fails to resolve the voltage issue, then appropriately reducing active power according to preset active power adjustment rules. This fully utilizes the reactive power regulation function inherent in the photovoltaic inverter, minimizing the waste of photovoltaic power generation resources. Furthermore, the active power adjustment introduces two selectable or parallel control methods: percentage regulation and absolute value regulation, significantly improving the flexibility and scenario adaptability of the control strategy.

[0032] In one embodiment, the step of generating a hierarchical step-by-step control strategy based on the real-time operating parameters and the voltage over-limit type and controlling the photovoltaic inverter to execute it further includes: When the voltage over-limit type is the low voltage over-limit and the real-time active power data is less than the rated power data, primary regulation is triggered to generate a third-level regulation command to control the photovoltaic inverter to adjust its own active power to the rated power data. The grid node voltage after the active power adjustment is collected as the third voltage data. When the voltage over-limit event occurs in the target transformer area based on the third voltage data, the secondary regulation is triggered to generate a fourth-level regulation command to control the photovoltaic inverter to adjust its own reactive power according to the preset reactive power adjustment rules. The grid node voltage after reactive power adjustment is collected as the fourth voltage data, and the judgment step of the voltage over-limit event and the reactive power adjustment step of the photovoltaic inverter are iteratively executed based on the fourth voltage data until the voltage over-limit event is eliminated.

[0033] Specifically, in the event of a voltage over-limit event in the target distribution area, if the type is low voltage exceeding the lower limit and the reactive power of the photovoltaic inverter is less than its rated power data, primary control is triggered, generating a third-level control command and sending it to the photovoltaic inverter so that it can increase its active power to the rated power data according to the third-level control command. Next, the grid node voltage after active power adjustment is obtained as the third voltage data. If it is within the preset voltage over-limit threshold, the control is determined to be effective, and step S4 is executed to enter the stability confirmation process; if it is not within the preset voltage over-limit threshold (that is, the voltage over-limit event has not been eliminated), the active power regulation is determined to be insufficient to solve the low voltage problem, secondary control is triggered, generating a fourth-level control command and sending it to the photovoltaic inverter so that it can adjust its reactive power according to the preset reactive power adjustment rules according to the fourth-level control command. Subsequently, the grid node voltage after reactive power adjustment is collected and used as the fourth voltage data. The fourth voltage data and the preset voltage over-limit threshold are used to perform the voltage over-limit event judgment step. If the over-limit event still exists, the reactive power of the photovoltaic inverter is adjusted according to the above adjustment rules. This process is repeated until the voltage over-limit event is eliminated.

[0034] The preset reactive power adjustment rule is configured to adjust the percentage of reactive power based on a preset reactive power amplitude, and / or adjust the value of reactive power based on a preset absolute reactive power value. In other words, the preset reactive power adjustment rule includes two modes, which can be selected via a configuration file as a single mode or a combination of modes: Percentage adjustment mode: Adjusts the percentage of reactive power based on a preset reactive power amplitude. For example, setting the reactive power increase amplitude to 10% increases the reactive power by 10% each time a control command is issued. Note that percentage adjustment is ineffective when the initial reactive power value is 0; in this case, absolute value adjustment should be used. Or, absolute value adjustment mode: Adjusts the value of reactive power based on a preset absolute reactive power value. For example, setting the absolute reactive power increase to 0.3 kVar increases the reactive power by 0.3 kVar each time a control command is issued. Or, combination mode: Allows setting absolute value adjustment first, then switching to percentage adjustment when the reactive power rises to a certain threshold (the specific value can be manually set according to requirements, which will not be elaborated here). It is important to note that the increase in reactive power is limited by the inverter capacity. The apparent power of the photovoltaic inverter must not exceed its rated capacity. Therefore, when increasing reactive power, the current active power must also be considered to ensure that the apparent power limit is met. If the capacity limit has been reached and the voltage has not recovered, the current reactive power output should be maintained and an alarm should be issued.

[0035] Furthermore, when the over-limit type is the low voltage lower limit and the real-time active power data equals the rated power data, the secondary control is directly triggered, and the fourth-level control command is issued to the photovoltaic inverter. In other words, in the case of low voltage lower limit, if the active power of the photovoltaic inverter equals the rated power (i.e., it is at full capacity), the fourth control command is directly issued to the photovoltaic inverter, prioritizing voltage boosting through reactive power compensation, without needing an active power boosting step.

[0036] This invention employs a layered control strategy of "active power regulation first, reactive power adjustment later" in low-voltage scenarios: first, active power is increased to the rated power to ensure power generation; then, the grid connection voltage is increased by improving line impedance, thereby increasing power generation revenue; finally, reactive power adjustment further stabilizes the voltage, significantly improving the utilization rate of photovoltaic power generation. This control method enables distributed photovoltaic systems to maximize their power generation capacity under different operating conditions, improving the energy efficiency of distributed photovoltaic systems and promoting the effective utilization of clean energy.

[0037] S4. When the updated output parameters meet the dual-dimensional preset stability conditions, issue a control command to the photovoltaic inverter and generate a control end event. In one embodiment, issuing a control command to the photovoltaic inverter when the updated output parameters meet the two-dimensional preset stability conditions includes: When the updated grid node voltage continues to operate within the preset voltage over-limit threshold for a preset number of cycles, and the updated real-time operating parameters recover to the preset output benchmark corresponding to the voltage over-limit type, a control command to stop adjustment is issued to the photovoltaic inverter; wherein, the preset output benchmark corresponding to the overvoltage over-limit is that the active power of the photovoltaic inverter is equal to the rated power data; the preset output benchmark corresponding to the low voltage over-limit is that the reactive power of the photovoltaic inverter is equal to zero.

[0038] Specifically, when the updated grid node voltage obtained after eliminating voltage over-limit events can continue to operate within the preset voltage over-limit threshold for a preset number of cycles, and the real-time operating parameters at this time recover to the preset output benchmark corresponding to the voltage over-limit type, it indicates that the output parameters obtained after executing the control command meet the dual-dimensional preset stability conditions. A stop control command is then generated and sent to the photovoltaic inverter to end the control process and maintain the current operating parameters without further power adjustment. Simultaneously, the fusion terminal exits the control state, returns to the periodic monitoring mode of step S1, and generates a control end event. The preset number of cycles is set to 3 monitoring cycles by default. If the monitoring cycle is 5 seconds, it needs to remain stable for 15 seconds. This number of cycles can be adjusted through a configuration file. For example, in scenarios with high grid stability requirements, it can be increased to 5 cycles; in scenarios with large grid fluctuations but allowing for short-term fluctuations, it can be reduced to 2 cycles.

[0039] The preset output benchmark for overvoltage exceeding the upper limit is: active power equals the rated power of the photovoltaic inverter. That is, after the voltage stabilizes, if reactive power has returned to zero, active power should be restored to the rated output to avoid power generation losses caused by long-term power rationing. The preset output benchmark for undervoltage exceeding the lower limit is: reactive power equals 0. That is, after the voltage stabilizes, reactive power compensation should be turned off to reduce unnecessary reactive power losses and improve the power factor.

[0040] The control termination event records complete control information corresponding to voltage over-limit events, including basic event information: control start time, end time, over-limit type (overvoltage / undervoltage), over-limit phase (A / B / C / three-phase), and over-limit amplitude; control process information: control command sequence (sending time and content of the first / second / third / fourth control commands), voltage response curves after each adjustment, and active / reactive power change trajectories; control result information: final stable voltage value, final active / reactive power, and control success indicator; statistical data: total control duration, estimated active power loss (if active power is reduced), and reactive power compensation. This event is stored in the system database and can be queried and analyzed through the operation and maintenance platform. Operation and maintenance personnel can use this data to identify weak points in the distribution area and optimize control parameters, such as appropriately lowering the voltage over-limit threshold or increasing the active power reduction step size for areas with frequent overvoltages.

[0041] In addition, if no voltage over-limit event occurs in the target distribution area, the output parameters are continuously and periodically monitored to maintain real-time awareness of the grid status and ensure an immediate response when a voltage over-limit event occurs.

[0042] This invention avoids voltage "rebound" or "oscillation" problems after regulation by setting up a multi-dimensional stability verification mechanism, ensuring the long-term stability of the power grid. Simultaneously, the generated regulation event records provide maintenance personnel with traceable data analysis data, which helps to optimize regulation parameters for different photovoltaic output characteristics of different distribution areas, further improving the system's adaptability and regulation efficiency. Thus, after the voltage recovers to the normal range and meets the preset stability conditions, the issuance of regulation commands can be automatically terminated, allowing the output parameters of the photovoltaic inverter to return to the preset benchmark state. This ensures continuous voltage stability and allows distributed photovoltaics to operate in a more optimal output mode after the voltage problem is resolved. For example, when the low voltage exceeding the lower limit problem is resolved, reactive power returns to 0, and the photovoltaic inverter does not need to continuously maintain reactive power compensation, thereby reducing internal component losses and extending equipment lifespan. Conversely, when the overvoltage exceeding the upper limit problem is resolved, active power returns to the rated output, maximizing the utilization of photovoltaic resources and improving power generation efficiency. Meanwhile, the preset stability conditions avoid frequent adjustments caused by short-term voltage fluctuations, enhance the stability and reliability of the adjustment process, and ensure that the output regulation of distributed photovoltaic power generation accurately responds to the grid voltage demand while balancing equipment operating efficiency and energy utilization efficiency.

[0043] This application proposes a distributed photovoltaic (PV) output control method to address the issue of improving the efficiency and accuracy of PV output regulation. By real-time monitoring of output parameters in the target distribution area and setting differentiated over-limit judgment rules, it achieves real-time perception of the distribution network's operating status and can quickly respond to voltage over-limit issues caused by distributed PV output fluctuations. Compared to traditional solutions relying on capacitor bank switching and on-load tap-changing transformers, this invention eliminates the need for numerous additional traditional regulation devices. Voltage regulation can be achieved solely through the active and reactive power regulation capabilities of the PV inverter itself, effectively avoiding lifespan losses caused by frequent equipment operation. A hierarchical, step-by-step regulation strategy is employed to classify and regulate the PV inverter, preventing simultaneous and batch disconnection of PV inverters due to sudden voltage spikes. This minimizes the waste of PV power generation resources, significantly improves the utilization rate of PV power generation, enhances the efficiency and accuracy of distributed PV output regulation, and prevents drastic power fluctuations or even power outages caused by chain reactions, thereby improving grid safety and stability.

[0044] It should be noted that although the steps in the flowchart above are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order requirement for the execution of these steps, and they can be executed in other orders.

[0045] In another embodiment, such as Figure 2As shown, a second aspect of the present invention provides a distributed photovoltaic power output control system, including a low-voltage distribution network. The low-voltage distribution network includes a fusion terminal 201, a photovoltaic inverter 203, a photovoltaic miniature circuit breaker 202 (i.e., a photovoltaic-specific miniature circuit breaker), and a communication conversion interface 204; wherein, The fusion terminal 201 is used to execute the distributed photovoltaic power output control method as described in the first aspect; The photovoltaic micro-circuit 202 is connected to the photovoltaic inverter 203 and the fusion terminal 201 respectively, and is used to transmit the real-time operating parameters of the photovoltaic inverter 203 and the grid node voltage of the low-voltage distribution network to the fusion terminal 201, and to provide circuit continuity protection when the low-voltage distribution network has a circuit abnormality. The photovoltaic inverter 203 is connected to the photovoltaic micro-circuit 202 through the communication conversion interface 204, and is used to receive and execute the control commands sent by the fusion terminal 201.

[0046] It should be noted that each module in the aforementioned distributed photovoltaic power output control system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module. For specific limitations regarding a distributed photovoltaic power output control system, please refer to the limitations regarding a distributed photovoltaic power output control method above; both have the same function and role, and will not be repeated here.

[0047] In summary, this invention relates to the field of power regulation technology and discloses a method and system for regulating distributed photovoltaic (PV) output. It periodically monitors the real-time operating parameters of PV inverters in a target distribution area and the grid node voltages of the low-voltage distribution network. Combined with a preset voltage over-limit threshold, it determines whether a voltage over-limit event has occurred in the target distribution area according to differentiated judgment rules and marks the voltage over-limit type corresponding to the event. After an over-limit event occurs, a hierarchical step-by-step regulation strategy is generated based on the real-time operating parameters and the voltage over-limit type, and the PV inverter is controlled to execute it, thereby updating the grid node voltage. When the updated voltage data meets the dual-dimensional preset stability conditions, a stop regulation command is issued to the PV inverter, and a regulation end event is generated. This eliminates the need for a large number of traditional regulation devices; precise voltage regulation can be achieved solely through the regulation capabilities of the PV inverter itself, effectively avoiding lifespan loss caused by frequent equipment operation.

[0048] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0049] The embodiments described above are merely preferred embodiments of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the technical principles of this invention, and these improvements and substitutions should also be considered within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the scope of the claims.

Claims

1. A method for regulating distributed photovoltaic power output, characterized in that, include: Periodically monitor the output parameters of the target transformer area; the output parameters include the real-time operating parameters of the photovoltaic inverter and the grid node voltage of the low-voltage distribution network; Based on the grid node voltage and the preset voltage over-limit threshold, determine whether a voltage over-limit event has occurred in the target transformer area according to the differentiated judgment rules, and mark the voltage over-limit type corresponding to the voltage over-limit event; Based on the real-time operating parameters and the voltage over-limit type, a hierarchical step-by-step control strategy is generated and the photovoltaic inverter is controlled to execute it in order to update the output parameters; When the updated output parameters meet the dual-dimensional preset stability conditions, a control command is issued to the photovoltaic inverter, and a control end event is generated.

2. The distributed photovoltaic power output regulation method according to claim 1, characterized in that, The grid node voltage includes the first phase voltage, the second phase voltage, and the third phase voltage; the preset voltage over-limit thresholds include an upper voltage over-limit threshold and a lower voltage over-limit threshold; wherein... The process of determining whether a voltage over-limit event has occurred in the target transformer area based on the grid node voltage and a preset voltage over-limit threshold, according to a differentiated judgment rule, and marking the voltage over-limit type corresponding to the voltage over-limit event, includes: When the voltage of the first phase, the voltage of the second phase, or the voltage of the third phase exceeds the voltage over-limit threshold, it is determined that the voltage over-limit event has occurred, and the voltage over-limit type corresponding to the voltage over-limit event is marked as overvoltage over-limit. When the first phase voltage, the second phase voltage, and the third phase voltage are all less than the voltage lower limit threshold, it is determined that the voltage limit event has occurred, and the voltage limit type corresponding to the voltage limit event is marked as low voltage lower limit.

3. The distributed photovoltaic power output regulation method according to claim 2, characterized in that, The real-time operating parameters include real-time reactive power data; wherein... The step of generating a hierarchical, step-by-step control strategy based on the real-time operating parameters and the voltage over-limit type, and controlling the photovoltaic inverter to execute it, includes: When the voltage over-limit type is the overvoltage over-limit and the real-time reactive power data is greater than the preset reactive power threshold, primary regulation is triggered to generate a first-level regulation command to control the photovoltaic inverter to adjust its own reactive power to zero. The grid node voltage after reactive power adjustment is collected as the first voltage data. When the voltage over-limit event occurs in the target transformer area based on the first voltage data, secondary regulation is triggered to generate a second-level regulation command to control the photovoltaic inverter to adjust its own active power according to the preset active power adjustment rules. The grid node voltage after the active power adjustment is collected as the second voltage data, and the judgment step of the voltage over-limit event and the active power adjustment step of the photovoltaic inverter are iteratively executed based on the second voltage data until the voltage over-limit event is eliminated.

4. The distributed photovoltaic power output regulation method according to claim 3, characterized in that, The method further includes: when the over-limit type is the overvoltage over-limit and the real-time reactive power data is equal to zero, directly triggering the secondary control and issuing the secondary control command to the photovoltaic inverter.

5. The distributed photovoltaic power output regulation method according to claim 3, characterized in that, The preset active power adjustment rule is configured to adjust the power percentage of the active power according to a preset active power amplitude, and / or to adjust the value of the active power according to a preset active power absolute value.

6. The distributed photovoltaic power output regulation method according to claim 2, characterized in that, The real-time operating parameters include real-time active power data and rated power data; wherein... The step of generating a hierarchical, step-by-step control strategy based on the real-time operating parameters and the voltage over-limit type, and controlling the photovoltaic inverter to execute it, includes: When the voltage over-limit type is the low voltage over-limit and the real-time active power data is less than the rated power data, primary regulation is triggered to generate a third-level regulation command to control the photovoltaic inverter to adjust its own active power to the rated power data. The grid node voltage after the active power adjustment is collected as the third voltage data. When the voltage over-limit event occurs in the target transformer area based on the third voltage data, the secondary regulation is triggered to generate a fourth-level regulation command to control the photovoltaic inverter to adjust its own reactive power according to the preset reactive power adjustment rules. The grid node voltage after reactive power adjustment is collected as the fourth voltage data, and the judgment step of the voltage over-limit event and the reactive power adjustment step of the photovoltaic inverter are iteratively executed based on the fourth voltage data until the voltage over-limit event is eliminated.

7. A method for regulating distributed photovoltaic power output according to claim 6, characterized in that, The method further includes: when the over-limit type is the low voltage over-limit and the real-time active power data is equal to the rated power data, directly triggering the secondary control and issuing the fourth-level control command to the photovoltaic inverter.

8. A method for regulating distributed photovoltaic power output according to claim 6, characterized in that, The preset reactive power adjustment rule is configured to adjust the power percentage of the reactive power according to a preset reactive power amplitude, and / or to adjust the value of the reactive power according to a preset reactive power absolute value.

9. A method for regulating distributed photovoltaic power output according to claim 6, characterized in that, When the updated output parameters meet the dual-dimensional preset stability conditions, a control command is issued to the photovoltaic inverter, including: When the updated grid node voltage continues to operate within the preset voltage over-limit threshold for a preset number of cycles, and the updated real-time operating parameters recover to the preset output benchmark corresponding to the voltage over-limit type, a control command to stop adjustment is issued to the photovoltaic inverter; wherein, the preset output benchmark corresponding to the overvoltage over-limit is that the active power of the photovoltaic inverter is equal to the rated power data; the preset output benchmark corresponding to the low voltage over-limit is that the reactive power of the photovoltaic inverter is equal to zero.

10. A distributed photovoltaic power output regulation system, characterized in that, This includes a converged terminal, a photovoltaic inverter, a photovoltaic micro-circuit, and a communication conversion interface; among which, The fusion terminal is used to execute the distributed photovoltaic power output regulation method as described in any one of claims 1 to 9; The photovoltaic micro-circuit is connected to the photovoltaic inverter and the fusion terminal respectively, and is used to transmit the real-time operating parameters of the photovoltaic inverter and the grid node voltage of the low-voltage distribution network to the fusion terminal, and to provide circuit continuity protection when the low-voltage distribution network has a circuit abnormality. The photovoltaic inverter is connected to the photovoltaic micro-circuit via the communication conversion interface, and is used to receive and execute the control commands sent by the fusion terminal.

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