Network construction energy storage reactive power collaborative optimization control method and system

Abstract

The invention belongs to the technical field of electric power engineering, and particularly relates to a network construction energy storage reactive power collaborative optimization control method and system, and the method comprises the steps: obtaining a local voltage target value of network construction energy storage, a control dead zone of an AVC system, and a sum of voltage target values in different periods, and determining an effective regulation voltage interval [-, +] of AVC; and further calculating a self-adaptive voltage dead zone of network construction energy storage, so that an action voltage interval [-, +] of the self-adaptive voltage dead zone completely contains an effective regulation interval of AVC, and control isolation is realized. When the voltage of the grid-connected point is in the AVC interval, constructing a network, storing energy and silently outputting fixed reactive power; when the AVC interval is exceeded and the dead zone is still in the dead zone, the AVC is used for dominant adjustment; only when the dead zone is exceeded, network construction energy storage starts autonomous voltage regulation based on a dynamic voltage regulation coefficient. Reactive circulation and reverse adjustment are effectively avoided, and the system voltage control precision and the operation economy are improved.

Description

Reactive power coordinated optimization control method and system for grid-connected energy storage Technical Field

[0001] This invention belongs to the field of power engineering technology, specifically a method and system for reactive power coordinated optimization control of grid-connected energy storage. Background Technology

[0002] The statements in this section merely refer to the background art related to this invention and do not necessarily constitute prior art.

[0003] Grid-based energy storage technology, which can simulate the external characteristics of synchronous generators and actively provide voltage and frequency support to the power grid, has become a key piece of equipment for improving the stability of power grids with a high proportion of new energy sources, and is being widely used in new energy power plants.

[0004] In power plants incorporating grid-connected energy storage, there are typically multiple levels and types of reactive power and voltage control equipment, mainly including: Automatic Voltage Control (AVC) systems at the dispatch master station or power plant level, Static Var Generators (SVG) for continuous and rapid reactive power compensation, and grid-connected energy storage converters with autonomous adjustment capabilities. The ideal operating mode is for all equipment to coordinate and cooperate, with the AVC system making global optimization decisions, SVG and other equipment performing fine-tuning, and grid-connected energy storage responding to severe fluctuations.

[0005] However, in practical engineering applications, it has been found that due to the autonomous and rapid reactive power regulation capabilities of grid-connected energy storage based on local voltage measurements, there are serious control conflicts and coordination problems between it and the AVC system and other reactive power equipment. When voltage regulation is required at the substation (e.g., increasing the 35kV bus voltage), the autonomous control logic of the grid-connected energy storage may interpret this as a positive voltage deviation, thus absorbing reactive power. This contradicts the "reactive power output" command issued by the AVC system to the SVG. This "reverse regulation" leads to ineffective reactive power circulation between reactive power equipment within the substation, causing not only additional equipment losses and energy waste but also severely weakening the overall reactive power support efficiency of the system. Summary of the Invention

[0006] This invention provides a method and system for reactive power collaborative optimization control of grid-connected energy storage, aiming to solve the "reactive power contention" problem caused by the conflict between the autonomous voltage regulation of grid-connected energy storage and the control objectives of existing reactive power equipment such as AVC systems and SVG in new energy power plants. Its fundamental goal is to transform grid-connected energy storage into a "collaborator" through an intelligent parameter coordination and configuration method. While ensuring that daily voltage stability control is dominated by existing equipment, it maximizes the energy storage's ability to quickly support the grid during severe fluctuations, thereby improving the economy, accuracy, and safety of voltage control throughout the power plant.

[0007] The first aspect of this invention discloses a reactive power coordinated optimization control method for grid-connected energy storage, comprising the following steps: obtaining the local voltage target value of grid-connected energy storage. Automatic voltage control system (AVC) control dead zone and time-of-use voltage target values and Determine the effective regulation voltage range of the AVC system. - , + Based on the acquired , , and Calculate the adaptive voltage dead zone of grid-connected energy storage This enables the operating voltage range of the grid-connected energy storage system. - , + It fully encompasses the effective regulating voltage range of all AVC systems; it collects the voltage at the grid connection point of the grid-connected energy storage system. ,according to The interval in which it is located is subject to hierarchical control, specifically: if If the voltage range is within the effective regulation range of the AVC system, the grid-connected energy storage output will be fixed reactive power. ;like If the voltage exceeds the effective regulation range of the AVC system but falls within the operating voltage range of grid-connected energy storage, the AVC system will control its subordinate reactive power equipment to regulate the voltage, and the grid-connected energy storage will maintain a fixed reactive power output. ;like If the voltage exceeds the operating voltage range of the grid-connected energy storage, the grid-connected energy storage will initiate autonomous voltage regulation, and its output will be reactive power. ,in This is the dynamic voltage regulation coefficient.

[0008] Furthermore, adaptive voltage dead zone The calculation satisfies the following constraints: ; ;in, , These are the upper and lower limits for bus voltage operation, respectively.

[0009] Furthermore, adaptive voltage dead zone The calculation formula is: ; ; ; ;in, For the set interval, For safety margin coefficient, The current reactive power output for grid-connected energy storage is... The value after first-order low-pass filtering.

[0010] Furthermore, determine the dynamic voltage regulation coefficient. As shown in the following formula: ;in, As the reference voltage regulation coefficient, The equivalent impedance of the grid connection point is measured in real time. Voltage at grid connection point The standard deviation within a set time window; This is a fixed coefficient set based on the critical voltage fluctuation.

[0011] Furthermore, determine the reference voltage regulation coefficient. As shown in the following formula: ;in, Obtained through on-site step test. .

[0012] Furthermore, fixed coefficient The calculation formula is: ,in, The minimum voltage regulation coefficient required to maintain the minimum voltage regulation capability. This is the set standard deviation of the critical voltage fluctuation.

[0013] Furthermore, the safety margin coefficient The following safety constraints determine the maximum reactive power output of grid-connected energy storage: Under extreme operating conditions, its maximum potential voltage dead zone The following formula must be satisfied: ;in, The maximum reactive power that the energy storage device can output. For the verification parameters, For safety reasons, and These are the maximum permissible dead zones on the upper and lower voltage limits, respectively.

[0014] A second aspect of the present invention discloses a reactive power coordinated optimization control system for grid-connected energy storage, comprising: a data acquisition module configured to: acquire the local voltage target value of grid-connected energy storage. Automatic voltage control system (AVC) control dead zone and time-of-use voltage target values and The preprocessing module is configured to: determine the effective regulation voltage range of the AVC system. - , + The preprocessing module is also configured to: based on the acquired... , , and Calculate the adaptive voltage dead zone of grid-connected energy storage This enables the operating voltage range of the grid-connected energy storage system. - , + The system fully encompasses the effective regulating voltage range of the AVC system; the control output module is configured to: adjust according to the grid connection point voltage of the energy storage system. The interval in which it is located is subject to hierarchical control, specifically: if If the voltage range is within the effective regulation range of the AVC system, the grid-connected energy storage output will be fixed reactive power. ;like If the voltage exceeds the effective regulation range of the AVC system but falls within the operating voltage range of grid-connected energy storage, the AVC system will control its subordinate reactive power equipment to regulate the voltage, and the grid-connected energy storage will maintain a fixed reactive power output. ;like If the voltage exceeds the operating voltage range of the grid-connected energy storage, the grid-connected energy storage will initiate autonomous voltage regulation, and its output will be reactive power. ,in This is the dynamic voltage regulation coefficient.

[0015] A third aspect of the present invention discloses a computer program product including computer-readable instructions, which, when executed on an electronic device, enable the electronic device to implement the above-described grid-based energy storage reactive power collaborative optimization control method.

[0016] A fourth aspect of the present invention discloses an electronic device, including at least one processor and a memory connected to the processor, the memory being used to store a computer program; the processor being used to execute the computer program, enabling the electronic device to implement the above-described grid-based energy storage reactive power collaborative optimization control method.

[0017] Compared with existing technologies, the above one or more technical solutions have the following beneficial effects: 1. By setting an adaptive voltage dead zone for grid-connected energy storage, its operating range mathematically surrounds the effective adjustment range of the AVC system. This achieves "zoning" from a control logic perspective. When the voltage is within the preset normal adjustment range of the AVC, the grid-connected energy storage is forcibly locked in a static state with fixed reactive power output. This avoids grid-connected energy storage making "reverse adjustment" actions contrary to AVC commands due to autonomous judgment, and eliminates ineffective reactive power circulating currents generated within the power station due to opposite reactive power output directions. It also reduces the additional losses of equipment such as converters and transformers, improving the overall operational economy of new energy power stations.

[0018] 2. The voltage dead zone can be smoothly adjusted according to the current reactive power output of the energy storage system. When the output is high, the dead zone can be appropriately widened to avoid frequent operation. The voltage regulation coefficient Kv is based on the real-time grid impedance Zg and the voltage oscillation level σ.U Dynamic adjustment enables the control system to match the strength and dynamic characteristics of the power grid in real time: automatically enhancing regulation capabilities under weak grid conditions, and suppressing response intensity to prevent exacerbating instability when voltage oscillations are detected. Simultaneously, offline safety locking of the parameter adaptive range is achieved through a safety margin coefficient, ensuring that regardless of how online parameters are adaptively adjusted, the operating boundary always remains far from the safe operating limits of the power grid, providing quantifiable safety redundancy for the system.

[0019] 3. A tiered coordination strategy of "AVC priority, grid-based energy storage as backup" is adopted. The control process mandates that grid-based energy storage can only initiate powerful autonomous regulation when the voltage deviation exceeds the AVC's handling capacity (i.e., exceeds the AVC dead zone) and further deteriorates to the point of triggering the grid-based energy storage's own dead zone. This prioritizes the regulation potential of conventional reactive power resources such as SVG and wind turbines, enabling grid-based energy storage to serve as a "reserve" during most normal fluctuations. It balances the utilization rate of various reactive power devices, reduces the operating losses of grid-based energy storage, and fully preserves the rapid dynamic reactive power capacity of grid-based energy storage. When the grid encounters severe disturbances, grid-based energy storage can be quickly deployed to provide instantaneous reactive power support, thereby enhancing the station's ability to cope with transient stability issues such as voltage spikes / dips. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 is a schematic diagram of reactive power control for grid-connected energy storage provided by one or more embodiments of the present invention; Figure 2 is a schematic diagram of power station architecture provided by one or more embodiments of the present invention; Figure 3 is a schematic diagram of grid-connected control provided by one or more embodiments of the present invention; Figure 4 is a schematic diagram of voltage fluctuation based on simulation experiments provided by one or more embodiments of the present invention; Figure 5 is a schematic diagram of reactive power fluctuation based on simulation experiments provided by one or more embodiments of the present invention; Figure 6 is a schematic diagram of voltage per-unit value changing over time provided by one or more embodiments of the present invention; Figure 7 is a schematic diagram of reactive power changing over time provided by one or more embodiments of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] The following are relatively less common technical terms used in this scheme and their definitions: Grid-based energy storage refers to an energy storage system that can actively support the grid in terms of voltage and frequency by simulating the characteristics of a synchronous generator. It possesses autonomous regulation capabilities and is not merely a load device following the grid. Reactive power grabbing refers to the phenomenon where, when the system needs to regulate voltage, multiple reactive power regulation devices (such as grid-based energy storage, SVG, and AVC) experience conflicting control objectives or response characteristics, resulting in inconsistent reactive power output directions and mutual cancellation, leading to reduced regulation efficiency or even ineffectiveness.

[0025] Reverse regulation specifically refers to the action where the reactive power output of grid-connected energy storage is opposite to the system voltage regulation demand. For example, when the system needs to increase the voltage, it should generate reactive power, but grid-connected energy storage absorbs reactive power, resulting in reactive power waste.

[0026] AVC (Automatic Voltage Control) refers to a closed-loop control system that automatically sends instructions to reactive power equipment (such as wind turbines and SVG) within the power grid dispatching master station or station-level system based on the bus voltage target, thereby achieving voltage optimization.

[0027] An SVG (Static Var Generator) is a power electronic reactive power compensation device that uses a switchable power electronic device (such as an IGBT) to form an inverter, directly generating or absorbing continuously adjustable reactive current. It can be understood as a controllable reactive current source connected in parallel with the power grid.

[0028] As described in the background section, grid-connected energy storage (Grid-connected Energy Storage) possesses autonomous and rapid reactive power regulation capabilities based on local voltage measurements. However, this leads to significant control conflicts and coordination challenges with the AVC system and other reactive power equipment. These challenges manifest primarily as follows: 1. Reactive power circulation and reverse regulation issues: When voltage regulation is required at the substation (e.g., increasing the 35kV bus voltage), the autonomous control logic of the Grid-connected Energy Storage may interpret this as a positive voltage shift, thus absorbing reactive power. This contradicts the "reactive power output" command issued by the AVC system to the SVG. This "reverse regulation" results in ineffective reactive power circulation between reactive power equipment within the substation, causing not only additional equipment losses and energy waste but also severely weakening the overall reactive power support efficiency of the system.

[0029] 2. Control Target Conflict Issue: The AVC system dynamically sets the target voltage value at the power station's grid connection point based on superior dispatch instructions or the 24-hour optimization curve. However, the local voltage reference value for grid-connected energy storage is typically statically set or based on a different set of logic. When these targets are inconsistent, the grid-connected energy storage attempts to pull the voltage towards its own target value, while the AVC system attempts to pull it towards the dispatch target value. This "tug-of-war" keeps the voltage in a state of adjustment for extended periods, making it difficult to stabilize at the expected value. This reduces voltage control accuracy and forces the grid-connected energy storage to continuously output reactive power, shortening its effective operating time as an energy storage unit.

[0030] 3. Lack of systematic and adaptive parameter settings: Existing grid-connected energy storage control parameters are mostly factory-fixed values ​​or set based on rough experience from isolated scenarios. They cannot adapt to complex operating conditions such as changes in grid topology, switching of operating modes, and significant fluctuations in renewable energy output. Under weak grid conditions, a fixed Kv value may lead to over-regulation and oscillations; under strong grid conditions, it may result in insufficient regulation. Fixed dead-zone settings fail to achieve a dynamic balance between "avoiding frequent actions" and "ensuring rapid response."

[0031] Therefore, this solution provides a method and system for coordinated reactive power optimization control of grid-connected energy storage, designing an adaptive dead zone positively correlated with reactive power output, ensuring its lower limit is greater than the adjustment dead zone of the AVC system. This ensures that within normal, small voltage fluctuation ranges, grid-connected energy storage remains "silent," completely handing over regulation power to AVC and SVG, fundamentally avoiding conflicts. Simultaneously, a voltage regulation coefficient is designed to dynamically adjust with grid impedance and voltage oscillation levels. This allows the voltage regulation coefficient Kv to match grid strength in real time (impedance adaptation) and automatically reduce its response intensity when voltage oscillations are detected (oscillation suppression), ensuring its action is both fast and effective without exacerbating system instability.

[0032] As shown in Figure 1, the reactive power coordinated optimization control method for grid-connected energy storage includes the following steps: obtaining system parameters, specifically: obtaining the target voltage value U of the grid-connected energy storage. ref The control dead zone U of the AVC device mks and its time-segmented voltage target value U msref U mxref ; Calculate AVC dead zone: U mxref -U mks U msref +U mks ; Computational network energy storage dead zone U dead Actual acquisition terminal voltage U g ; Determine U g Is it within the AVC dead zone: If U g If it is in the AVC dead zone, then output Qv=Qref; if U g Not in the AVC dead zone, and U g If it is within the dead zone of the grid-connected energy storage, then AVC controls the reactive power output; if U g Not in the AVC dead zone, and U g If the energy storage system is not within the grid-connected dead zone, calculate the voltage regulation coefficient Kv and output Q. v =Q ref +Kv×(U ref -U g +U dead ).

[0033] The specific process of this scheme will be described in detail below, referring to the following definitions of terms.

[0034] Voltage dead zone (U dead In this scheme, "voltage deviation" refers to the allowable range set to avoid frequent equipment operation. When the voltage deviation is within this range, the grid-connected energy storage will not output reactive power regulation commands; regulation will only be initiated when the voltage deviation exceeds this range.

[0035] The voltage regulation coefficient (Kv) is a proportional coefficient in the reactive power-voltage droop control of grid-connected energy storage. It represents the amount of reactive power adjustment corresponding to a unit voltage deviation, reflecting the sensitivity and strength of its regulation.

[0036] Adaptive dead zone, the dynamic dead zone concept proposed in this scheme, refers to the dead zone size being adjustable according to the current reactive power output level (Q) of the grid-connected energy storage. filte r) Automatic adjustment to achieve selective and sensitive optimization under different operating conditions.

[0037] Equivalent impedance (Z) g Kv refers to the real-time equivalent grid impedance viewed from the grid connection point of the energy storage system towards the system side. It is used to reflect the strength of the grid and is a key parameter for dynamically adjusting Kv.

[0038] Safety margin constraints: The design principle proposed in this scheme requires that the dead zone boundary of grid-connected energy storage be kept at a certain distance (e.g., ≥1.1 times the dead zone) from the upper and lower limits of the grid operating voltage to ensure the robustness of control.

[0039] Reactive power filtering (Q filter By performing a first-order low-pass filter on the current reactive power output, a smoothed reactive power value is obtained, which is used for dead-zone adaptive calculation to avoid frequent changes in the dead zone due to instantaneous fluctuations.

[0040] Figure 3 shows a schematic diagram of the network control system, where the parameters for the primary frequency modulation section are as follows: Angular frequency refers to the angular frequency form of the system's rated frequency; the measured angular frequency of the power grid ( ), refers to the angular frequency corresponding to the measured current system frequency; primary frequency modulation ratio ( ), reflecting the active power regulation corresponding to a unit frequency deviation; primary frequency regulation power increment ( This refers to the adjustment amount that directly converts frequency deviation into active power, and its calculation formula is: External active power reference ( ), refers to the power bias provided for primary frequency regulation; actual output active power ( The active power output from the converter side is... .

[0041] The parameters for the inertia and damping module are as follows: mechanical torque equivalent conversion factor ( This section will adjust the primary frequency modulation output power. Acceleration torque converted into virtual rotor Virtual moment of inertia ( ), simulating the inertia of a synchronous generator rotor, The larger the value, the stronger the "inertial buffer" of frequency fluctuations, and the better the system's ability to resist disturbances; the virtual damping coefficient ( (), simulating the damping characteristics of a rotor to suppress frequency oscillations, The larger the value, the faster the convergence speed of frequency fluctuations; angular frequency deviation ( The acceleration torque is calculated using inertia and damping parameters: Voltage phase angle ( ), obtained by integrating the angular frequency: This determines the phase of the output alternating current.

[0042] The reactive power control values ​​for grid-connected energy storage are as follows: ; ; Voltage regulation coefficient, The reactive power target value for grid-connected energy storage Target voltage value for grid-connected energy storage This is the measured value of the terminal voltage. Voltage dead zone value of grid-connected energy storage.

[0043] The control range is limited by considering the grid connection voltage of the power station and the grid-connected energy storage access voltage.

[0044] First, the allowable operating range of the bus voltage is determined according to the dispatching procedures, and its upper and lower limits are obtained. , Secondly, obtain the control dead zone (±) set by the AVC system. ) and its time-period voltage target values ​​( , Finally, based on the above parameters, the voltage dead zone (±) of the grid-connected energy storage system is calculated and set. ).

[0045] The constraints on the above parameters are given in the following equation: ; ;in, , These are the upper and lower limits corresponding to the grid-connected energy storage bus. , For the upper and lower target values ​​at different time periods, ± For the upper and lower dead zones of the AVC device, ± This is to address the dead zone of grid-connected energy storage voltage operation.

[0046] To meet the above constraints, it is necessary to improve the selectivity, sensitivity, and redundancy of the control. This involves setting the dead zone closer to... and The addition of a range of 0.002 to 0.005 enhances selectivity and relative sensitivity, while increasing redundancy by moving it away from the upper and lower limits of the busbar. Furthermore, by adding an adaptive term positively correlated with reactive power output, the dead zone is intelligently adjusted according to the actual operating status of the equipment, further optimizing the coordination of selectivity and sensitivity under different operating conditions.

[0047] Dead Zone The calculation formula is as follows: ; ; ; ; This represents the current reactive power output value of the energy storage device. These are the filter coefficients, used for first-order filtering of reactive power to smooth out reactive power fluctuations. .

[0048] ;( ;( .

[0049] By controlling the relationship between dead zones and safety boundaries, sufficient safety margins are provided to ensure control redundancy and robustness, and this is used to obtain the coefficients. As shown in the following formula: ;in, The maximum reactive power output of the energy storage device. The maximum dead zone was calculated. Thus obtain The value is used to ensure the safety margin of the dead zone and safety boundary of the grid-connected energy storage.

[0050] The above formula constructs the theoretically largest possible dead zone. The scenario is described, and its safety is verified, including the following steps: Define the maximum basic dead zone. (Corresponding to the first formula); Calculate the maximum dead zone under the two boundary conditions respectively. and Soon Substitute into the dead zone The calculation formulas calculate the maximum dead zone values ​​that may occur on the upper voltage limit side and the lower voltage limit side respectively (corresponding to the second and third formulas). and It is the action boundary of AVC; it determines the global maximum dead zone. (Corresponding to the fourth formula); Add safety margin constraints and calculate the coefficients. (Corresponding to the last formula), the left side of the equal sign represents the target value of the grid-connected energy storage voltage. Up to the voltage safety limit stipulated by the dispatching authority or lower limit The minimum distance is used to obtain the final safety boundary for allowable voltage fluctuations; the right side of the equation indicates that this final safety boundary must be at least the maximum possible dead zone. 2.1 times that.

[0051] By controlling the instantaneous reactive power range, we can ensure that the current energy storage device does not frequently output reactive power, thereby ensuring a more balanced reactive power distribution among various reactive power devices.

[0052] The voltage regulation coefficient was verified by combining the measured equivalent impedance and voltage of the station.

[0053] At both high-power (greater than 70% output) and low-power (greater than 30% output) conditions at the power station, voltage or reactive power step tests are conducted using reactive power control (AVC) or reactive power compensation (SVG) devices to verify the correlation between reactive power and voltage, and to determine the average reactive power value corresponding to each 0.01 pu voltage change. . The rated power for grid-connected energy storage.

[0054] theory By calculating the grid connection impedance and voltage, to... Adjustments are made as shown in the following formula: ; ; ;in, The equivalent impedance measured in real time at the grid connection point. The equivalent impedance under stable operation. By measuring the equivalent impedance, we can ensure... It can match the topological changes and strength of the power grid in real time. The grid connection point voltage is at the first The instantaneous measurement value at each sampling time. To measure the average voltage, The standard deviation of voltage, As a real-time quantitative indicator for judging the dynamic instability of a system, and reflecting the degree of voltage oscillation, when the voltage oscillates, Increase This reduces the reactive power output, thereby controlling its stability.

[0055] The calculation process for the set fixed coefficient is as follows: ; To maintain the voltage regulation coefficient at the lowest voltage regulation capability, The sampling occurs when the voltage fluctuation reaches a critical point. Ensure voltage regulation coefficient It can guarantee the minimum voltage regulation capability.

[0056] The above control process can be summarized as follows: Step 1: Obtain and calculate system parameters; Step 2: Calculate the dead zone U of the grid-connected energy storage. dead Step 3: Collect voltage and determine the region.

[0057] In step 1, obtain U ref U mks U msref U mxref And calculate the effective action area of ​​AVC: [U msref +U mks U mxref -U mks ]. Among them, U msref +U mks and U mxref -U mks These two values ​​constitute the actual voltage thresholds at which the AVC starts to increase or decrease reactive power regulation, thus providing a precise boundary for subsequent determination of which response should be given to the voltage deviation.

[0058] Step 2 then calculates the adaptive dead zone ±U according to the specific formula. dead And obtain the action boundary of grid energy storage: [U ref -U dead U ref +U dead During this period, Uref±U is ensured through constraints. dead The range completely covers the effective action area of ​​AVC in the previous step (i.e., U). ref -U dead msref +U mks And U ref +U dead >U mxref -U mks (and leave a safety margin).

[0059] This step physically achieves responsibility isolation. The "non-operating zone" of grid-connected energy storage is wider than the "operating zone" of AVC. When the voltage fluctuates within the responsibility zone of AVC, the grid-connected energy storage will inevitably be in its own dead zone, thus being prohibited from operation by the control logic.

[0060] Step 3: Real-time data acquisition of U g And determine which control area it falls into.

[0061] Scenario A: U g Within the AVC dead zone (U msref +U mks ≤U g ≤U mxref -U mks ​In this case, the voltage is within the ideal target band, a result of AVC regulation. The grid-connected energy storage output Qref (usually 0 or a fixed reference) is completely silent, resolving the "reactive power grab" problem under steady-state conditions. At this time, AVC can independently and precisely regulate devices such as SVG, without interfering with grid-connected energy storage.

[0062] Situation B: U g Beyond the AVC dead zone, but within the grid-connected energy storage dead zone (U ref -U dead ≤U g msref +U mks or U mxref -U mks g ≤U ref +U dead) In this situation, the voltage has deviated from the ideal value, but the degree of deviation has not yet triggered the emergency response threshold of grid-connected energy storage, which is considered a "relatively large but still acceptable fluctuation." At this time, the reactive power output is controlled by the AVC (calling resources such as SVG and wind turbines). By prioritizing the use of conventional resources, the AVC system has the "priority" and "time window" to handle fluctuations, thus treating grid-connected energy storage as a "reserve" and avoiding unnecessary frequent actions.

[0063] Case C: U g Beyond the grid-connected energy storage dead zone (U g ref -U dead or U g >U ref +U dead In this situation, if the voltage fluctuates drastically or fails, exceeding the safety buffer zone, the AVC system may be unable to correct it quickly (or respond inadequately). At this point, the autonomous droop control Q of the grid-connected energy storage system is activated. v =Q ref +K v ×(Ur ef -U g ±U dead It can rapidly generate or absorb large amounts of reactive power. At this time, the grid-connected energy storage can quickly suppress the risk of voltage collapse or severe oscillation. The dynamic adjustment of Kv (impedance self-adaptation, oscillation suppression) ensures its precise and stable operation.

[0064] ​​​By nesting the "AVC dead zone" within the "grid-based energy storage dead zone," the design ensures, in terms of physical logic, that grid-based energy storage remains inactive within the normal operating range of the AVC. In scenarios A and B, grid-based energy storage remains inactive or is dominated by the AVC, eliminating reactive power circulation and offsetting effects. Simultaneously, grid-based energy storage operates less frequently during daily fluctuations, fully preserving its dynamic reactive power capacity. In emergency situations like scenario C, it can provide ample and rapid reactive power support, enhancing the system's dynamic stability margin.

[0065] By clearly defining the zones, conflicts and energy consumption arising from differing objectives between AVC and grid-connected energy storage are avoided. Most of the time (situations A and B), control is delegated to AVC, which tracks and dispatches the target. Only in critical situations (situation C) does grid-connected energy storage intervene strongly, anchored by its own Uref. This clear distinction between primary and secondary roles ensures that voltage follows dispatch commands more accurately most of the time, while providing the fastest response in emergencies.

[0066] This solution reduces voltage control issues in grid-connected energy storage sites by modifying and verifying the control parameters of the grid-connected energy storage system, solves reverse reactive power losses, improves the dynamic reactive power support reserve of the grid-connected energy storage system, and further enhances system safety.

[0067] When multiple grid-connected energy storage stations with independent voltage regulation capabilities are connected to the same transmission channel or load center, if their reactive power control parameters (such as voltage reference value, droop coefficient, etc.) are set independently without system-level coordination, disorderly adjustment is very likely to occur due to conflicting control objectives.

[0068] Specifically, when a power station determines that it needs to increase reactive power output to support the voltage based on local voltage measurements, another power station may mistakenly determine that the voltage is over the limit due to parameter settings differences and reduce reactive power output. This "reverse regulation" phenomenon not only causes ineffective reactive power circulation between stations, resulting in additional energy loss (i.e., reactive reverse loss), but also seriously weakens the overall dynamic reactive power support capability of the regional power grid, causing a decrease in voltage stability margin.

[0069] The reactive power regulation scheme was tested on the 35kV side of the new energy power station. The station architecture is shown in Figure 2, which includes 500kV stations A and B. After being stepped down to 220kV, the voltage reaches the 35kV new energy power station. The 35kV new energy power station corresponding to station A includes grid-type energy storage, wind power, and SVG. The 35kV new energy power station corresponding to station B includes conventional energy storage, wind power, SVG, and synchronous condenser.

[0070] Since the allowable deviation of 35 kV voltage is -3% to +7% of the corresponding system nominal voltage, (33.95-37.45 kV) is the boundary point. According to relevant specifications, such as the "Technical Guidelines for Voltage and Reactive Power in Power Systems" (GB / T 40427-2021), reactive power control should be less than the critical range of 34-37 kV (-2.85% to 5.71%). The target value of 220 kV is generally around 230 kV, which is 1 kV higher during the day than at night. The target value deviation should be converted to a standard of 0.0045. The dead zone of AVC is generally 300-500V. It will generally activate when the fluctuation exceeds (0.13% to 0.227%). To solve the problem of reactive power regulation competing for reactive power, the dead zone of grid-connected energy storage needs to be set to be greater than the dead zone of AVC (in combination with the fluctuation of the dispatch target value) but less than the critical range. This can reduce the reverse regulation and reactive power waste of grid-connected energy storage. Given the voltage regulation dead zone. =0.01. The experimental results combined with Figures 4 and 5 show that the reactive power change of the grid has no effect within the 0.01 dead zone range, but quickly adjusts after exceeding it to pull the voltage back to the corresponding fluctuating voltage value.

[0071] The existing reactive power dispatch strategy, given the upper and lower limits of the 220kV and 35kV bus voltages (225-238kV, 34-37kV), adjusts reactive power with the 220kV bus voltage as the target point, using a constant voltage mode. The values ​​issued vary for different power plants, and reactive power generation is prioritized. The reactive power regulation capacity of wind turbines (PV matrices) is utilized first; when the reactive power regulation capacity of wind turbines (PV matrices) is exhausted, the reactive power regulation capacity of SVG (SVC) is then utilized. When the reactive power regulation capacity of SVG (SVC) is also exhausted, the grid-connected energy storage system autonomously adjusts. The adjustment effect comparison after adding optimized parameters to the grid-connected energy storage system with the fast response equipment is shown in Figures 6 and 7.

[0072] In Figures 6 and 7, the horizontal axis represents time, the vertical axis of Figure 6 represents the per-unit voltage value, and the vertical axis of Figure 7 represents reactive power. The curves in Figure 6 show the changes in bus voltage over time for energy storage without a grid, for energy storage with a grid without dead zones, and for energy storage with a grid with dead zones. The upper and lower limits of the bus voltage, the target and upper / lower limits of the AVC voltage, and the upper and lower dead zones of the grid-connected energy storage voltage are also marked. The curves in Figure 7 show the changes in bus reactive power over time for energy storage with dead zones and for energy storage with dead zones.

[0073] Correspondingly, the reactive power coordinated optimization control system for grid-connected energy storage includes: a data acquisition module configured to acquire the local voltage target value of the grid-connected energy storage. Automatic voltage control system (AVC) control dead zone and time-of-use voltage target values and The preprocessing module is configured to: determine the effective regulation voltage range of the AVC system. - , + The preprocessing module is also configured to: based on the acquired... , , and Calculate the adaptive voltage dead zone of grid-connected energy storage This enables the operating voltage range of the grid-connected energy storage system. - , + It fully encompasses the effective regulating voltage range of all AVC systems; the control output module is configured to: adjust according to the grid connection point voltage of the energy storage system. The interval in which it is located is subject to hierarchical control, specifically: if If the voltage range is within the effective regulation range of the AVC system, the grid-connected energy storage output will be fixed reactive power. ;like If the voltage exceeds the effective regulation range of the AVC system but falls within the operating voltage range of grid-connected energy storage, the AVC system will control its subordinate reactive power equipment to regulate the voltage, and the grid-connected energy storage will maintain a fixed reactive power output. ;like If the voltage exceeds the operating voltage range of the grid-connected energy storage, the grid-connected energy storage will initiate autonomous voltage regulation, and its output will be reactive power. ,in This is the dynamic voltage regulation coefficient.

[0074] Correspondingly, a computer program product includes computer-readable instructions that, when executed on an electronic device, cause the electronic device to implement the aforementioned grid-connected energy storage reactive power coordinated optimization control method.

[0075] Correspondingly, an electronic device includes at least one processor and a memory connected to the processor, the memory being used to store computer programs; the processor is used to execute the computer programs, enabling the electronic device to implement the above-mentioned grid-based energy storage reactive power coordinated optimization control method.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for coordinated optimization control of reactive power in grid-connected energy storage, characterized in that, Includes the following steps: Obtain the local voltage target value for grid-connected energy storage Automatic voltage control system (AVC) control dead zone and time-of-use voltage target values and Determine the effective regulation voltage range of the AVC system. - ， + Based on the acquired 、 、 and Calculate the adaptive voltage dead zone of grid-connected energy storage This enables the operating voltage range of the grid-connected energy storage system. - ， + It fully encompasses the effective adjustable voltage range for all AVC systems; Collect grid-connected voltage of energy storage system ,according to The interval in which it is located is subject to hierarchical control, specifically: if If the voltage range is within the effective regulation range of the AVC system, the grid-connected energy storage output will be fixed reactive power. ； like If the voltage exceeds the effective regulation range of the AVC system but falls within the operating voltage range of grid-connected energy storage, the AVC system will control its subordinate reactive power equipment to regulate the voltage, and the grid-connected energy storage will maintain a fixed reactive power output. ； like If the voltage exceeds the operating voltage range of the grid-connected energy storage, the grid-connected energy storage will initiate autonomous voltage regulation, and its output will be reactive power. ,in This is the dynamic voltage regulation coefficient.

2. The reactive power coordinated optimization control method for grid-connected energy storage as described in claim 1, characterized in that, Adaptive voltage dead zone The following constraints must be met: ； ;in, ， These are the upper and lower limits for bus voltage operation, respectively.

3. The reactive power coordinated optimization control method for grid-connected energy storage as described in claim 1, characterized in that, Determine the adaptive voltage dead zone As shown in the following formula: ； ； ； ;in, For the set interval, For safety margin coefficient, The current reactive power output for grid-connected energy storage is... The value after first-order low-pass filtering.

4. The reactive power coordinated optimization control method for grid-connected energy storage as described in claim 3, characterized in that, Safety margin coefficient The following safety constraints determine the maximum reactive power output of grid-connected energy storage: Under extreme operating conditions, its maximum potential voltage dead zone The following formula must be satisfied: ;in, The maximum reactive power that the energy storage device can output. For the verification parameters, For safety reasons, and These are the maximum permissible dead zones on the upper and lower voltage limits, respectively.

5. The reactive power coordinated optimization control method for grid-connected energy storage as described in claim 1, characterized in that, Determine the dynamic voltage regulation coefficient As shown in the following formula: ;in, As the reference voltage regulation coefficient, The equivalent impedance of the grid connection point is measured in real time. Voltage at grid connection point The standard deviation within a set time window; This is a fixed coefficient set based on the critical voltage fluctuation.

6. The reactive power coordinated optimization control method for grid-connected energy storage as described in claim 5, characterized in that, Determine the reference voltage regulation coefficient As shown in the following formula: ;in, Obtained through on-site step test. 。 7. The reactive power coordinated optimization control method for grid-connected energy storage as described in claim 5, characterized in that, Fixed coefficient The calculation formula is: ,in, The minimum voltage regulation coefficient required to maintain the minimum voltage regulation capability. This is the set standard deviation of the critical voltage fluctuation.

8. A grid-connected energy storage reactive power coordinated optimization control system, characterized in that, include: The data acquisition module is configured to acquire the local voltage target value for grid-connected energy storage. Automatic voltage control system (AVC) control dead zone and time-of-use voltage target values and The preprocessing module is configured to: determine the effective regulation voltage range of the AVC system. - ， + The preprocessing module is also configured to: based on the acquired... 、 、 and Calculate the adaptive voltage dead zone of grid-connected energy storage This enables the operating voltage range of the grid-connected energy storage system. - ， + It fully encompasses the effective regulating voltage range of all AVC systems; the control output module is configured to: adjust according to the grid connection point voltage of the energy storage system. The interval in which it is located is subject to hierarchical control, specifically: if If the voltage range is within the effective regulation range of the AVC system, the grid-connected energy storage output will be fixed reactive power. ； like If the voltage exceeds the effective regulation range of the AVC system but falls within the operating voltage range of grid-connected energy storage, the AVC system will control its subordinate reactive power equipment to regulate the voltage, and the grid-connected energy storage will maintain a fixed reactive power output. ； like If the voltage exceeds the operating voltage range of the grid-connected energy storage, the grid-connected energy storage will initiate autonomous voltage regulation, and its output will be reactive power. ,in This is the dynamic voltage regulation coefficient.

9. A computer program product, characterized in that, It includes computer-readable instructions that, when executed on an electronic device, cause the electronic device to perform the steps in the grid-connected energy storage reactive power collaborative optimization control method as described in any one of claims 1-7.

10. An electronic device, characterized in that, It includes at least one processor and a memory connected to the processor, the memory being used to store a computer program; the processor is used to execute the computer program, enabling the electronic device to implement the steps in the grid-connected energy storage reactive power coordinated optimization control method as described in any one of claims 1-7.

Images