A new energy gathering station power regulation method

Abstract

This application discloses a power regulation method for a new energy collection station, comprising: matching the capacity of the grid-type SVG, energy storage, and static synchronous condenser according to the location of the collection station, and constructing a three-layer collaborative architecture of master station-collection station co-control-site station; based on the equipment capacity regulation controller, enabling the grid-type equipment to operate in PV mode within the full voltage normal operating range; the master station calculates the optimal voltage target value; the co-control layer calculates the total reactive power demand accordingly and allocates it to each device according to the principle of overall planning; generates a voltage reference value; and issues instructions and receives actual feedback through a fast communication channel to achieve closed-loop regulation. During low voltage ride-through or high voltage ride-through, the grid-type equipment switches to transient support mode, prioritizing the output of the maximum reactive current, and coordinating the regulation of SVG, energy storage, and synchronous condenser to eliminate reactive power contention and circulating current, reduce voltage reactive power sensitivity, retain SVG to cope with transients, and significantly improve voltage stability and support efficiency.

Description

Technical Field

[0001] This invention relates to the field of new energy power technology, and in particular to a power regulation method for a new energy collection station. Background Technology

[0002] With the accelerated construction of new power systems and the continuous increase in the grid-connected capacity of new energy sources, 500 kV new energy collection stations, as key nodes for large-scale wind and solar power grid integration, are crucial for the safe operation of the power grid due to their voltage stability and power regulation capabilities. Currently, new energy collection stations are typically equipped with grid-type static var generators (SVG), grid-type energy storage, and static synchronous condensers to provide instantaneous and dynamic active / reactive power support and reduce risks such as phase-locked synchronization and transient overvoltage. However, the capacity configuration of existing grid-type equipment lacks differentiated design for different grid node locations, resulting in inconsistent support effects and making it difficult to achieve optimal performance.

[0003] Taking a typical 500 kV renewable energy collection station in the Northeast China Power Grid (such as the Fushun collection station) as an example, the current practice is to configure a grid-type SVG (Static Var Generator) with 5%–10% of the main transformer capacity on the 66 kV side of the collection station, and a grid-type energy storage system with 10%–20% of the renewable energy capacity in a centralized sharing mode. Static synchronous condensers or distributed synchronous condensers are also configured on the renewable energy plant side according to short-circuit ratio requirements. However, in actual operation, these devices all operate according to the traditional PQ (Power Quantity) node control mode: the dispatching master station calculates the voltage target value for each grid connection point based on sensitivity, issues a command every 5 minutes, and each substation's AVC (Active Voltage Control) automatically supports reactive power according to the command. Because the action delay is as long as minutes, the problem of reactive power contention between plants is prominent; at the same time, the lack of PV (Polymer Transmission Unit) nodes within the collection station makes the randomness and volatility of renewable energy generation highly susceptible to voltage fluctuations, seriously affecting the voltage stability of the collection station and the receiving-end power grid.

[0004] Further analysis reveals that while grid-connected equipment currently possesses the capability for reactive power response within milliseconds during non-high / low voltage ride-through processes, its control mode remains PQ mode, which cannot meet the requirements for strong voltage support. When grid-connected equipment attempts to switch to PV mode (constant active power, voltage amplitude directly set by the controller), grid-connected equipment (such as conventional wind turbines and photovoltaic inverters) within the power station operate simultaneously with the grid-connected equipment. If the reactive power is not properly coordinated, reactive power circulation can easily occur—that is, one device generates capacitive reactive power while another absorbs an equal amount of inductive reactive power, resulting in reactive power idling. This not only fails to support the bus voltage but also increases equipment losses and heat generation, severely affecting the regulation speed and accuracy of automatic voltage control (AVC).

[0005] Furthermore, the grid-type SVG, grid-type energy storage, and reactive power resources (such as wind turbine converters and photovoltaic inverters) within the collection station have not yet achieved unified steady-state capacity allocation and coordinated control. Each device operates independently, lacking rapid communication and unified dispatch commands. The existing dispatch master station issues commands with an excessively long cycle (5 minutes), which cannot adapt to the second-level fluctuations in renewable energy output, resulting in lagging voltage regulation. At the same time, the rapid reactive power response capability of the grid-type SVG is reserved for low-voltage ride-through needs, but its capacity is not rationally utilized during normal operation; although the grid-type energy storage has continuous dynamic reactive power regulation capability, it lacks a coordinated allocation mechanism with the SVG and synchronous condensers; and the transient voltage fluctuation response capability of the static synchronous condenser, as a rapid reactive power source, is also not fully utilized in steady-state regulation. Summary of the Invention

[0006] This application provides a power regulation method for a new energy collection station. By coordinating multiple types of resources within the collection station, such as grid-type SVG, grid-type energy storage, and static synchronous condensers, for voltage / reactive power regulation, it avoids reactive power contention caused by the original 5-minute delay. Through PV mode and communication channels, it reduces the voltage reactive power sensitivity coefficient and eliminates reactive power circulation within and between stations. It retains the capacity of the grid-type SVG to meet low-voltage ride-through requirements and improves transient voltage stability. It is applicable to different grid node locations in a 500 kV new energy collection station and achieves optimal support through capacity matching.

[0007] This application provides a power regulation method for a new energy collection station, including: S101, Based on the location of the aggregation station, use matching rules to match the capacity of network-type equipment; construct a three-level control architecture for the aggregation station, which includes a master station layer, an aggregation station co-control layer, and a field station layer; S102, based on the network equipment capacity regulation equipment controller, enables the network equipment to operate in PV mode within the full voltage normal operation range; the master station layer calculates the optimal voltage target value and transmits it to the aggregation station co-control layer. The aggregation station co-control layer calculates the total reactive power demand based on the received optimal voltage target value. The aggregation station co-control layer allocates the total reactive power demand to each network equipment and station based on the network equipment capacity, and generates the voltage reference value for each equipment. S103, the station layer includes grid-following equipment and network-building equipment. The network-building equipment tracks the voltage reference value, while the grid-following equipment switches to current source mode and sets a reactive power-voltage dead zone. The aggregation station control layer monitors the reactive power of each device in real time. If the reactive power of two devices is detected to be in opposite directions, the voltage reference value of one of them is adjusted until the reactive power circulation is eliminated. S104, a communication channel is established between the aggregation station control layer, the field station layer, and the network equipment. The communication channel allocates the calculated reactive power using the principle of overall allocation. The field station equipment feeds back the actual reactive power output and voltage value to the aggregation station control layer in real time through the communication channel. S105 When low voltage ride-through or high voltage ride-through is detected, the network-type equipment switches to transient support mode, prioritizes outputting the maximum reactive power current, and the collection station co-control layer suspends command transmission. After the voltage is restored, it re-enters the PV co-control mode.

[0008] Preferably, the specific steps for matching the capacity of grid-type equipment according to the location of the collection station include: dividing the collection station nodes into near-area weak grid nodes, load center nodes, and new energy rich nodes; calculating the multi-infeed short-circuit ratio of the collection station grid connection point, and increasing the capacity of grid-type equipment if the multi-infeed short-circuit ratio is less than a preset critical value; using electromagnetic transient simulation to simulate the peak value of bus overvoltage after a fault, and configuring more reactive power regulation equipment if the overvoltage exceeds 1.3 pu; the grid-type equipment includes grid-type SVG, grid-type energy storage, and static synchronous condenser.

[0009] Preferably, the PV mode refers to the external control characteristics of the grid-connected equipment under normal operating conditions: constant active power and active setting and maintenance of voltage amplitude. Constant active power means that the equipment operates according to the scheduling plan and does not change the active power output due to voltage fluctuations. Active setting and maintenance of voltage amplitude means that the equipment, as a voltage source, no longer passively follows the grid fluctuations in its grid connection point voltage amplitude. Instead, the equipment controller sets a reference value and adjusts the no-power output to make the actual voltage track the reference value.

[0010] Preferably, the formula for calculating the total reactive power demand is: ,in, This represents the total non-regulating power demand at time t. This represents the voltage deviation at time t. This is the proportionality coefficient. The integral coefficient is... For the current moment, This is a virtual integral variable used in integral operations.

[0011] Preferably, the method for setting the reactive power-voltage dead zone is as follows: when the absolute value of the deviation between the grid connection point voltage and the rated value is less than 2%, the reactive power output of the grid-connected equipment is forcibly locked to the current value or zero; when the absolute value of the deviation is greater than or equal to 2%, the grid-connected equipment outputs reactive power according to the preset droop curve.

[0012] Preferably, the power regulation method further includes: S201 collects the grid connection point voltage, calculates the voltage deviation value based on the grid connection point voltage and the optimal voltage target value, and decomposes the voltage deviation value into low-frequency components and high-frequency components through a filter. S202, measure the frequency change rate at the grid connection point, construct a frequency-reactive power reverse channel based on the frequency change rate, output reactive power regulation amount from the frequency-reactive power reverse channel, and obtain reactive power reference value based on reactive power regulation amount, high frequency component and steady state base point. S203, based on the low-frequency component obtained by monitoring, compare the low-frequency component with a threshold. If the absolute value of the low-frequency component is greater than the preset threshold, perform on-load tap changer control and mechanical energy storage. S204 performs power regulation based on the reactive power reference value and the on-load tap changer control results.

[0013] Preferably, the method for constructing the frequency-reactive power reverse channel is as follows: the frequency change rate at the grid connection point is calculated in real time using a phase-locked loop, and then multiplied by a negative adaptive coefficient to obtain the reactive power regulation amount that is opposite to the direction of frequency change. ,in, Let be the reactive power adjustment at time t. The reverse coupling coefficient, This represents the rate of change of the frequency at which the equipment connects to the grid.

[0014] Preferably, the formula for calculating the reactive power reference value is: ,in, This is the reference value for the reactive power of the equipment. As the steady-state reactive power baseline, This is the voltage regulation coefficient. For high-frequency components, The reverse coupling coefficient, This represents the rate of change of the frequency at which the equipment connects to the grid.

[0015] Preferably, the on-load tap changer control includes: when the absolute value of the low-frequency component is greater than the threshold and the duration exceeds 30 seconds, determining the direction of action and sending an up or down command to the OLTC controller; 50ms before the OLTC action, sending a pre-compensation command to the SVG / energy storage to temporarily increase its output; and at the moment of OLTC switching, absorbing the reactive pulse released by the contact spring by reverse adjusting the output of the SVG / energy storage.

[0016] Preferably, the power regulation method further includes: S301, a distributed corona electrode array is formed by installing a ring-shaped corona electrode group on the conductor of the collection station; S302, based on the ion regulation voltage generated by the discharge of the distributed corona electrode array, the power is regulated by the voltage regulation result, and the regulation level of the voltage is matched and adjusted based on the voltage deviation value. The regulation level includes a fine adjustment layer, a medium adjustment layer and a coarse adjustment layer.

[0017] One or more technical solutions provided in this application have at least the following technical effects or advantages: They coordinate the use of multiple types of resources within the substation, such as grid-type SVG, grid-type energy storage, and static synchronous condensers, for voltage / reactive power regulation, avoiding reactive power contention caused by the original 5-minute delay; they reduce the voltage reactive power sensitivity coefficient and eliminate reactive power circulation within and between substations through PV mode and communication channels; they retain the capacity of grid-type SVG to meet low-voltage ride-through requirements and improve transient voltage stability; and they are applicable to different grid node locations in 500 kV renewable energy substations, achieving optimal support through capacity matching. Low-frequency voltage deviation is handled by the high-speed OLTC, while SVG / energy storage only handles high-frequency fluctuations, reducing heat loss; the reverse reactive-frequency channel can reduce frequency overshoot in weak grids, the energy storage of OLTC contact springs is actively utilized, and switching impacts are absorbed by power electronics, reducing voltage fluctuations. By using a distributed corona electrode array to achieve continuous stepless voltage fine-tuning, the power electronic and mechanical voltage regulating equipment is freed from daily minor fluctuations, significantly reducing its operating frequency and heat loss, forming a bottom-level regulation layer, and greatly improving the overall economic efficiency and equipment lifespan of the station. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating a power regulation method for a new energy collection station according to the present invention. Figure 2 This is a schematic diagram of the on-load tap changer control process of the present invention; Figure 3 This is a schematic diagram of the distributed corona electrode array of the present invention. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more complete description of this application will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of the present invention.

[0020] It should be noted that the terms "vertical," "horizontal," "up," "down," "left," "right," and similar expressions used in this article are for illustrative purposes only and do not represent the only possible implementation.

[0021] Unless otherwise defined, 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; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Example 1: Figure 1 This is a flowchart illustrating a power regulation method for a new energy collection station according to an embodiment of the present invention, including: S101, Based on the location of the aggregation station, use matching rules to match the capacity of network-type equipment; construct a three-level control architecture for the aggregation station, the three levels including the master station layer, the aggregation station co-control layer, and the field station layer; Specifically, for the access nodes of 500 kV renewable energy collection stations in the Northeast power grid, they are divided into three categories based on the strength of the power grid structure and operating characteristics: near-field weak grid nodes, load center nodes, and renewable energy-rich nodes. Near-field weak grid nodes have low short-circuit ratios, low grid inertia, weak voltage support capacity, and high risk of transient overvoltages. Load center nodes have high short-circuit ratios, robust power grid structures, dense loads, and voltage fluctuations are mainly caused by load changes. Renewable energy-rich nodes have a large number of wind and solar power collection points, resulting in drastic power output fluctuations, but the grid structure is relatively strong. The formula for calculating the multi-infeed short-circuit ratio at the grid connection point of the collection station is: ,in, For multi-feed short-circuit ratio, Let i be the three-phase short-circuit capacity of the i-th DC converter bus. The equivalent DC power is the total corrected power that takes into account other DC effects. The rated power of the i-th DC circuit. The rated power of the j-th DC circuit. Let be the mutual impedance between the i-th and j-th converter bus nodes. Let n be the self-impedance of the i-th converter bus node and n be the total number of DC feed-in circuits. A critical value is set based on the multi-feed-in short-circuit ratio calculated above. If the calculated multi-feed-in short-circuit ratio is less than the preset critical value, the capacity of the grid-connected equipment is increased. Electromagnetic transient simulation is used to simulate the peak bus overvoltage after a fault. If the overvoltage exceeds 1.3 pu, more reactive power regulation equipment is configured. The grid-connected equipment includes grid-connected SVG, grid-connected energy storage, and static synchronous condensers. The specific steps for matching the capacity of the grid-connected equipment using matching rules are as follows: For the capacity matching of the grid-connected SVG, the matching location is on the 66kV bus side of the collection station. One set is configured for each bus section, and the capacity is selected according to 5% to 10% of the rated capacity of the main transformer. For weak grid nodes, the upper limit of 10% is used to provide stronger transient voltage support. For load center nodes, the median value of 7.5% is used for daily reactive power regulation. For new energy enrichment nodes, the value is... The lower limit is 5%; for the capacity matching of grid-type energy storage, the matching location is to be centrally arranged within the collection station, connected to the 66kV or 35kV bus via a step-up transformer. The capacity is configured according to 10% to 20% of the total installed capacity of new energy connected to the collection station. The upper limit is 20% for weak grid nodes. At the same time, the energy storage is required to have grid control function. The median value is 15% for new energy rich nodes to suppress voltage fluctuations. The lower limit is 10% for load center nodes as reactive power reserve; for the capacity matching of static synchronous condensers, the matching location is the grid connection point of each new energy plant, i.e., the 35kV or 10kV bus side. The capacity is configured according to the short-circuit ratio requirement. Usually, the short-circuit ratio of the grid connection point of the new energy plant is not less than 1.5 to 2.0. Distributed synchronous condensers are configured. The capacity of the synchronous condensers at weak grid nodes is increased by an additional 30% to 50%. For collection stations that have been configured with SVG, the capacity of the synchronous condensers on the plant side can be appropriately reduced.

[0023] A three-layer collaborative control architecture is constructed, consisting of a master station layer, a collection station co-control layer, and a field station layer. The master station layer is responsible for optimizing the voltage / reactive power of the entire network, providing the voltage target values ​​for each 500kV collection station's grid connection point. The master station layer comprises an energy management system and a calculation engine. The collection station co-control layer receives commands from the master station, coordinates network equipment within the station and at the field station side, and achieves rapid voltage regulation. The collection station co-control layer consists of a collection station co-control system and a communication gateway. The field station layer executes commands from the co-control layer and provides feedback on local operating status. The field station layer comprises network equipment. The system consists of backup, grid-connected equipment, and AVC substations at new energy power plants. The master station layer calculates the optimal voltage target value for each collection station every minute and transmits it through the scheduling data network. After receiving the optimal voltage target value, the collection station co-control layer calculates the total reactive power demand based on the local measured voltage and decomposes it into voltage reference values ​​for each device according to the allocation principle. The grid-connected equipment at the power plant layer operates by tracking the voltage reference values, and the grid-connected equipment decides whether to intervene based on the dead zone. All devices feed back their status to the co-control layer, which adjusts the instructions for the next cycle based on the feedback information.

[0024] S102, based on the network equipment capacity regulation device controller, enables the network equipment to operate in PV mode within the full voltage normal operating range; the master station layer calculates the optimal voltage target value and transmits it to the aggregation station co-control layer. The aggregation station co-control layer calculates the total reactive power demand based on the received optimal voltage target value. The aggregation station co-control layer allocates the total reactive power demand to each network equipment and station based on the network equipment capacity, and generates voltage reference values ​​for each equipment; the PV mode refers to the active power remaining constant in the equipment control system, and the voltage amplitude being directly set and actively maintained by the controller; Furthermore, in power system control, PV mode refers to the external control characteristics of grid-connected equipment under normal operating conditions: constant active power and active setting and maintenance of voltage amplitude. Constant active power means that the equipment operates according to the active power command given by the dispatch plan or the collaborative control system, without changing its active power output due to voltage fluctuations. Active setting and maintenance of voltage amplitude means that the equipment, as a voltage source, no longer passively follows grid fluctuations in its grid connection point voltage amplitude, but instead has a reference value directly set by the equipment controller, and the actual voltage accurately tracks this reference value by rapidly adjusting the reactive power output. The steps for adjusting the equipment controller based on the grid-connected equipment capacity are as follows: Based on the grid-connected equipment capacity, each piece of equipment undergoes inner-loop controller modification, outer-loop controller modification, and the definition of the full-voltage normal operating range. The inner-loop controller modification adopts active power-frequency droop and reactive power-voltage droop. The voltage reference value for droop control is directly given by the collaborative control system. The inner-loop output is a PWM drive signal, controlling the switching action of IGBT / IGCT. An outer-loop voltage tracker is added to output the current reference value required by the inner loop. PV mode only applies when the voltage is between 0.9 pu and 1.1 pu. Effective upon pu; The optimal voltage target value for each 500 kV substation grid connection point is calculated using the interior-point method. This optimal voltage target value is calculated and transmitted every 1-5 minutes. The substation control system receives the optimal voltage target value through a communication gateway. Simultaneously, voltage transformers are used to measure the real-time voltage. Based on the optimal voltage target value and the real-time voltage, the total reactive power demand is calculated using the following formula: ,in, This represents the total reactive power regulation demand at time t. A positive value indicates that capacitive reactive power needs to be injected into the grid, while a negative value indicates that inductive reactive power needs to be absorbed. This represents the voltage deviation at time t. As a proportionality coefficient, it determines the sensitivity of the total reactive power demand to the current instantaneous voltage deviation. The integral coefficient determines the contribution of the integral term to eliminating steady-state voltage deviation. For the current moment, This refers to the virtual integral variable in the integral calculation; the aggregation station control layer allocates the total reactive power demand to each network-connected device and station based on the network equipment capacity. The allocation is based on the equipment capacity limit and a unified allocation principle, which prioritizes the reactive power supplied by network-connected energy storage devices. Network-connected SVGs undergo minor adjustments during normal operation. Static synchronous condensers serve as a fast reactive power source, while network-connected devices only supplement it. Based on the above, an allocation algorithm is used for allocation, and the formula is: ,in, The power allocated to the i-th device is zero. Let i be the available reactive power capacity of the i-th device. Let i be the priority weight of the i-th device. To determine the total power regulation demand, for grid-type equipment, the collection station control layer converts the allocated power into a voltage reference value using the following formula: ,in, This is the voltage reference value for the i-th device. For real-time voltage measurement at the substation and grid connection point, The power allocated to the i-th device is zero. The rated capacity of the i-th device The equivalent reactance between the grid connection point of the i-th device and the 500kV grid connection point of the collection station is given. After the distribution is completed, the collection station control layer obtains the reactive power or voltage reference value of each device and waits to send it through the communication channel of S104.

[0025] S103, the station layer includes grid-following equipment and network-building equipment. The network-building equipment tracks the voltage reference value, while the grid-following equipment switches to current source mode and sets a reactive power-voltage dead zone. The aggregation station control layer monitors the reactive power of each device in real time. If the reactive power of two devices is detected to be in opposite directions, the voltage reference value of one of them is adjusted until the reactive power circulation is eliminated. Specifically, the grid-connected and grid-building devices are simultaneously connected to the same bus. The grid-building devices dominate the voltage, and the outer loop controllers of all grid-building devices track the voltage reference value. The inner loop of the devices ensures that the actual grid-connected voltage tracks the voltage reference value. The converter control mode of the grid-connected devices is set to current source mode, with its d-axis current used to control active power and its q-axis current used to control reactive power, but it no longer participates in the voltage closed loop. The grid-connected devices do not actively adjust reactive power output based on voltage deviation. A voltage deviation dead zone is added to the reactive power controller of the grid-connected devices. When the absolute value of the deviation between the grid voltage and the rated value is less than 2%, the reactive power output of the grid-connected equipment is forcibly locked to the current value or zero and does not respond to voltage changes. When the absolute value of the deviation is greater than or equal to 2%, the grid-connected equipment outputs reactive power according to the preset droop curve. Through the voltage deviation dead zone, all voltage regulation tasks under normal operating conditions are undertaken by the grid-connected equipment, and the grid-connected equipment remains silent. This avoids the grid-connected equipment from having a conflict with the grid-connected equipment in terms of reactive power direction due to the difference in local voltage sensitivity, while also preserving the backup support capability of the grid-connected equipment under extreme voltage deviation. Real-time data collection of actual reactive power and grid connection point voltage for each device is used to establish a reactive power direction table for each device. For any two devices, if... , This indicates the direction of reactive power loss for the equipment. If the reactive power loss signs of two devices are opposite, it means that one device is emitting capacitive reactive power while the other absorbs an equal amount of inductive reactive power, forming a reactive power circulation. When reactive power circulation is detected, the circulation is eliminated. Specifically, the voltage reference command of grid-connected equipment takes precedence over grid-connected equipment. Among the grid-connected equipment, they are sorted by capacity and preset priority. The priority weights of the two devices are compared, and the device with the lower priority is selected. Its voltage reference value is adjusted in the direction of eliminating circulation. If the two devices have the same priority, the one with the smaller absolute value of actual reactive power is selected for adjustment. Each time an adjustment is made, the aggregation station control layer waits for one communication cycle and remeasures the reactive power loss of each device. If the circulation loss decreases, the adjustment continues in the same direction. If the circulation loss increases, the adjustment is reversed until the circulation loss is less than 5% of the total reactive power, i.e., the reactive power circulation is eliminated.

[0026] S104, a communication channel is established between the aggregation station control layer, the field station layer, and the network equipment. The communication channel allocates the calculated reactive power using the principle of overall allocation. The field station equipment feeds back the actual reactive power output and voltage value to the aggregation station control layer in real time through the communication channel. Furthermore, a communication channel is established between the aggregation station control layer and each substation and each network-connected device. Based on the IEC61850 standard, the reactive power command or voltage reference value of each device allocated by the aggregation station control layer in S102 is sent to the corresponding grid-connected and network-connected devices through the substation process layer network transmission. The actual reactive power, grid connection point voltage and device status are reported to the aggregation station control layer at a period of 200~500ms. After receiving the feedback data, the aggregation station control layer performs correction and compares the grid connection point voltage with the voltage reference value. If the deviation exceeds the preset threshold, the voltage reference value and reactive power of the device are adjusted in the next cycle.

[0027] S105 When a low-voltage ride-through or high-voltage ride-through is detected in the AC system, the network-type equipment switches to transient support mode, prioritizes the output of the maximum reactive power current, and the collection station co-control layer suspends command transmission. After the voltage is restored, it switches back to PV co-control mode.

[0028] Specifically, when a low-voltage ride-through (voltage drops below 0.9 pu) or a high-voltage ride-through (voltage rises above 1.1 pu) is detected in the AC system, the grid-type SVG, energy storage, and synchronous condenser automatically switch to transient support mode, prioritize the output of the maximum reactive power current, and the collection station co-control system issues a pause command. After the voltage returns to the normal range, it re-enters PV co-control.

[0029] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages: They coordinate the use of multiple types of resources within the substation, such as grid-type SVG, grid-type energy storage, and static synchronous condensers, for voltage / reactive power regulation, avoiding reactive power contention caused by the original 5-minute delay; reducing the voltage reactive power sensitivity coefficient and eliminating reactive power circulation within and between substations through PV mode and communication channels; preserving the capacity of the grid-type SVG to meet low-voltage requirements and improving transient voltage stability; and being applicable to different grid node locations in 500 kV new energy substations, achieving optimal support through capacity matching.

[0030] Example 2: Example 1 eliminated reactive circulating current within the station through three-layer coordinated control of grid-type equipment. However, all voltage regulation tasks were undertaken by power electronic devices such as SVG and energy storage, leading to long-term heavy-load operation when dealing with persistent low-frequency voltage deviations, resulting in significant heat loss and shortened equipment lifespan. This example assigns the low-frequency component to a high-speed OLTC, forming a hybrid coordination of power electronic high-frequency regulation and mechanical low-frequency regulation, reducing the continuous load rate of power electronic devices. Figure 2 As shown.

[0031] S201 collects the grid connection point voltage, calculates the voltage deviation value based on the grid connection point voltage and the optimal voltage target value, and decomposes the voltage deviation into low-frequency components and high-frequency components through a filter. Specifically, a high-speed on-load tap changer (OLTC) is installed on the main transformer at the substation. This OLTC employs a bipolar switching structure. Voltage and current transformers are installed at the grid connection point of the grid-connected equipment and the OLTC controller to measure voltage and frequency. The voltage transformers collect the instantaneous voltage value at the 500kV grid connection point, and the effective voltage value (grid connection point voltage) for each power frequency cycle is calculated. Based on the grid connection point voltage and the optimal voltage target value, the voltage deviation is calculated using the following formula: ,in, This represents the voltage deviation value. A positive value indicates that the actual voltage is lower than the target value, requiring the addition of capacitive reactive power (voltage boosting). A negative value indicates that the actual voltage is higher than the target value, requiring the absorption of inductive reactive power (voltage reduction). The optimal voltage target value, To measure the voltage at the grid connection point, a first-order Butterworth low-pass filter (LPF) is used to filter the voltage deviation value to obtain the low-frequency component. The cutoff frequency of the LPF is set to 0.03Hz. Changes below the cutoff frequency are considered low-frequency components, while changes above or equal to the cutoff frequency are considered high-frequency components. A first-order transfer function and a bilinear transform method are used. The first-order transfer function ensures a simple filter structure, small phase lag, and facilitates real-time control. The bilinear transform method converts the transfer function in the continuous domain into a difference equation in the discrete domain, enabling the calculation of the low-frequency component. The high-frequency component is obtained by subtracting the low-frequency component from the voltage deviation value.

[0032] S202, measure the frequency change rate at the grid connection point, construct a frequency-reactive power reverse channel based on the frequency change rate, output reactive power regulation amount from the frequency-reactive power reverse channel, and obtain reactive power reference value based on reactive power regulation amount, high frequency component and steady state base point. Furthermore, the method for constructing the frequency-reactive power reverse channel is as follows: The frequency change rate at the grid connection point is calculated in real time using a local phase-locked loop, and multiplied by a negative adaptive coefficient to obtain the reactive power regulation amount opposite to the direction of frequency change; each device tracks the angular frequency of the grid voltage in real time using the voltage transformer signal at its grid connection point via a three-phase phase-locked loop, converting the angular frequency into a frequency. ,in, The frequency at the current moment, Let be the angular frequency. Perform a first-order low-pass filter on the frequency to calculate the rate of change of frequency. The formula is: ,in, To represent the rate of change of the grid connection frequency of the device at time t, a positive value indicates that the frequency is increasing, and a negative value indicates that the frequency is decreasing. The frequency at the current moment, The frequency measured at the previous sampling time. Given the sampling period of the device controller, the obtained frequency change rate is multiplied by a negative adaptive coefficient to obtain the output reactive power regulation of the reverse channel: ,in, Let be the reactive power regulation amount generated by the frequency-reactive power reverse channel at time t. The reverse coupling coefficient, adjusted according to the short-circuit ratio of the power grid where the collecting station is located, determines the reverse modulation strength of the frequency change rate on the reactive power output. To represent the rate of change of the frequency at the grid connection point of the equipment, when the frequency increases (df / dt>0), When the value is negative, the equipment reduces capacitive reactive power (or increases inductive reactive power), thereby slightly lowering the voltage and suppressing further frequency increases; when the frequency decreases (df / dt<0), To achieve a positive value, the equipment adds capacitive reactive power, slightly raising the voltage to assist frequency recovery. The reactive power reference value is calculated based on the steady-state baseline, reactive power adjustment, and high-frequency components. The steady-state baseline is the reactive power level that the equipment should maintain in steady state. The high-frequency component is multiplied by the voltage regulation coefficient to obtain the high-frequency voltage response term, which is used to quickly suppress high-frequency fluctuations in the voltage. The formula for calculating the reactive power reference value is: ,in, This is the reference value for the reactive power of the equipment. As the steady-state reactive power baseline, This is the voltage regulation coefficient. For high-frequency components, The reverse coupling coefficient, To represent the rate of change of the grid connection point frequency of the equipment, the controller sends the reactive power reference value to the inner loop current control loop. After limiting, a PWM drive signal is generated, enabling the actual reactive power output of the equipment to quickly track the reference value. Through the above steps, the grid-connected equipment achieves local frequency-reactive power reverse modulation without relying on communication: the higher the rate of frequency change, the greater the reverse regulation. At the same time, the high-frequency voltage command and steady-state base point issued by the co-control are seamlessly superimposed, enabling the equipment to respond quickly to voltage fluctuations and actively suppress voltage-frequency coupling oscillations in weak grids, significantly improving system stability.

[0033] S203, based on the low-frequency component obtained by monitoring, compare the low-frequency component with a threshold. If the absolute value of the low-frequency component is greater than the preset threshold, perform on-load tap changer control and mechanical energy storage. Specifically, based on the monitored low-frequency components, a threshold is set, taking 5% of the rated voltage as the threshold. When the absolute value of the low-frequency component is greater than the preset threshold and the continuous duration exceeds 30 seconds, on-load tap changer control is performed. The control method is as follows: identify the direction of action. When the positive value of the low-frequency component is greater than the threshold, it indicates that the voltage needs to be increased, and an up-level command is sent to the OLTC controller. If the negative value of the low-frequency component is greater than the threshold, a down-level command is sent to the OLTC controller. 50 ms before sending the action command, a pre-compensation command is sent to the grid-type SVG and energy storage device currently undertaking the high-frequency component regulation task. The pre-compensation command requires the SVG / energy storage to temporarily increase reactive power output in the next 100~200 ms. When the OLTC contacts start to move, the SVG / energy storage has already established a reverse reactive current to offset the voltage jump at the moment of switching, so that the bus voltage remains smooth.

[0034] When the OLTC switches, the energy stored in its internal contact spring is rapidly released, generating a mechanical shock. This shock induces a reactive pulse in the transformer winding, which is equivalent to a mechanical virtual reactive power reserve. This reserve is utilized in the following way: at the same moment that the pre-compensation command is completed and the OLTC is activated, an ultra-short-time reverse adjustment command is sent to the SVG / energy storage, requiring it to output reactive current in the opposite direction to the previous pre-compensation. This reverse current precisely cancels out the reactive pulse generated by the release of the contact spring, so that the voltage waveform immediately returns to smoothness after the shock ends, avoiding the impact of voltage distortion on sensitive loads.

[0035] S204, power regulation is performed based on reactive power reference value and on-load tap changer control results; Furthermore, based on the reactive power reference value and the control results of the on-load tap changer, the power control system of the collection station performs power control. Specifically, the reactive power reference value of each grid-type device is used as a power command, which is transmitted to the corresponding device through the communication channel. Power factor commands are issued to the grid-connected devices to limit their reactive power output range, thereby avoiding their active participation in voltage regulation under normal operating conditions. Only when the voltage deviation exceeds the dead zone does the grid-connected device act as a backup supplement to the grid-type device according to the commanded power factor. The power factor refers to the ratio of active power to apparent power. The grid-type device immediately adjusts its own reactive power output according to the reactive power reference value to quickly respond to voltage fluctuations. The OLTC continuously adjusts the active / reactive power flow distribution by changing the transformer ratio to achieve mechanical power bias for low-frequency voltage deviations. Each device feeds back the actual reactive power output and grid connection point voltage to the control system in real time. The system compares the feedback value with the command value. If the deviation exceeds the allowable range (e.g., 5%), it is corrected in the next command cycle until both voltage deviation and frequency fluctuations are suppressed.

[0036] The technical solutions in the above embodiments of this application have at least the following technical effects or advantages: the low-frequency voltage deviation is borne by the high-speed OLTC, the SVG / energy storage only handles high-frequency fluctuations, and the heat loss is reduced; the reverse reactive-frequency channel can reduce frequency overshoot in weak power grids, the energy storage of the OLTC contact spring is actively utilized, and the switching impact is absorbed by power electronics, reducing voltage fluctuations.

[0037] Example 3: Example 2 reduced the continuous load rate of power electronic equipment and suppressed voltage-frequency oscillations by introducing a high-speed OLTC to share low-frequency voltage deviations. However, for daily small voltage fluctuations with amplitudes less than 0.5%, frequent SVG activation is still required. This not only causes unnecessary operation of power electronic equipment and heat loss, but also, the minimum adjustment step size of the SVG is usually about 0.1%, making it difficult to achieve finer steady-state error-free tracking. This example reduces the frequent operation of power electronic and mechanical equipment by adding a corona ion wind fine-tuning network, thus extending equipment lifespan. Figure 3 As shown.

[0038] S301, a distributed corona electrode array is formed by installing a ring-shaped corona electrode group on the conductor of the collection station; Specifically, a ring-shaped corona electrode group is installed every 20 meters along the line direction on each phase conductor of the collecting station, forming a distributed corona electrode array. The ring-shaped corona electrode group includes 6 star-shaped corona electrodes, deflection electrode plates, high-voltage insulators, and cables. The 6 star-shaped corona electrodes are evenly distributed along the circumference of the busbar, with the electrode tips facing outwards from the busbar. The material is a corrosion-resistant alloy. Each electrode on the deflection electrode plate is backed by a metal plate to generate a local electric field perpendicular to the busbar surface. The high-voltage insulators are used to connect the electrodes and the busbar conductors. The cables are shielded. Shielded cables are routed along the busbar to the ground control cabinet to reduce electromagnetic interference. The specific installation method is as follows: the three-phase busbars (phases A, B, and C) are installed independently, with each phase forming its own electrode array. The spacing between two adjacent electrode arrays is 20 meters. This distance is determined based on the effective drift range of corona ions in space—too dense will increase cost and wind resistance, while too sparse will result in discontinuous voltage regulation. Starting from the side of the busbar closest to the transformer, one set is installed at fixed intervals until the end of the busbar, ensuring that the entire busbar is covered by ions. The corona initiation voltage threshold of each set of electrodes is less than the peak value of the busbar's normal operating voltage.

[0039] S302, based on the ion regulation voltage generated by the discharge of the distributed corona electrode array, the power is regulated by the voltage regulation result, and the regulation level of the voltage regulation is matched based on the voltage deviation value. The regulation level includes a fine-tuning layer, a medium-tuning layer and a coarse-tuning layer. Furthermore, based on the voltage deviation value, the voltage adjustment level is matched, and a threshold range is set. All threshold ranges include a maximum threshold and a minimum threshold. When the absolute value of the voltage deviation is less than the minimum threshold, the system matches to the fine-tuning layer and activates the distributed corona electrode array for precise, zero-steady-state-error tracking. Based on the sign and magnitude of the voltage deviation, the required parameters are retrieved from a pre-generated corona current-deflection voltage-voltage adjustment table. If the voltage deviation is greater than zero, a deflection voltage with the opposite polarity to the bus voltage is applied, attracting ions generated by the corona to the conductor surface, increasing the equivalent capacitance to ground, and thus raising the voltage. If the voltage deviation is less than zero, a deflection voltage with the same polarity as the bus voltage is applied, repelling ions away from the conductor, reducing the equivalent capacitance to ground, and thus lowering the voltage. The system simulates the normal operating voltage of the bus through a high-voltage test platform and operates under different environmental conditions. Under these conditions, different corona currents and deflection voltages are applied to a single set of corona electrodes. Simultaneously, a high-precision voltage detection module measures minute changes in the bus voltage, recording the steady-state voltage regulation corresponding to each set of parameters. Measurement data under different humidity and temperature conditions are compiled into a corona current-deflection voltage-voltage regulation reference table: using humidity and temperature as indexes, and corona current and deflection voltage as inputs, the corresponding voltage regulation is output. When the absolute value of the voltage deviation is greater than or equal to the minimum threshold and less than the maximum threshold, and this persists for a period of time, the system is matched to the intermediate regulation layer, invoking SVG / energy storage to quickly generate or absorb reactive power. When the absolute value of the voltage deviation is greater than or equal to the maximum threshold, the system is matched to the coarse regulation layer, triggering a high-speed OLTC to change the transformer ratio for wide-range voltage regulation. The intermediate and coarse regulation layers work together to regulate the voltage. If the corona regulation capability is insufficient, SVG / energy storage is automatically supplemented. Rapidly output capacitive or inductive reactive power directly changes the reactive power injection into the bus, achieving medium-amplitude voltage regulation. When the deviation further expands or deviates for a long time, the OLTC will change the transformer ratio, continuously adjust the power flow distribution, and complete a wide range of voltage regulation. During the OLTC operation, the corona and SVG will be temporarily deactivated to avoid mutual interference; fine-tuning will be reactivated after recovery.

[0040] Power is regulated by adjusting voltage. For reactive power, the voltage regulation results are adjusted by modifying the equivalent capacitance or directly injecting reactive power to change the reactive power balance of the bus, so that the voltage returns to the target value. For active power, the OLTC changes the transformation ratio to redistribute the line power flow and affect the distribution of active power. At the same time, voltage stability also ensures that the active power output of new energy units does not disconnect from the grid due to voltage exceeding the limit, so that the voltage at the grid connection point of the collection station always follows the optimal target value. This ensures the hierarchical balance of reactive power and efficient transmission of active power in the AC grid, and ultimately achieves control with voltage regulation as the means and power balance as the goal.

[0041] The technical solutions in the above embodiments of this application have at least the following technical effects or advantages: by realizing continuous stepless fine adjustment of voltage through a distributed corona electrode array, the power electronic and mechanical voltage regulating equipment is freed from daily small fluctuations, significantly reducing its operation frequency and heat loss, forming a bottom-level regulation layer, and greatly improving the overall economic efficiency and equipment life.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. 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 power regulation method for a new energy collection station, characterized in that, include: S101, Match the capacity of network-type equipment according to the location of the aggregation station using matching rules; A three-tier control architecture for the aggregation station is constructed, comprising a master station layer, an aggregation station co-control layer, and a field station layer. S102, based on the network equipment capacity regulation equipment controller, enables the network equipment to operate in PV mode within the full voltage normal operation range; the master station layer calculates the optimal voltage target value and transmits it to the aggregation station co-control layer. The aggregation station co-control layer calculates the total reactive power demand based on the received optimal voltage target value. The aggregation station co-control layer allocates the total reactive power demand to each network equipment and station based on the network equipment capacity, and generates the voltage reference value for each equipment. S103, the station layer includes grid-following equipment and network-building equipment. The network-building equipment tracks the voltage reference value, while the grid-following equipment switches to current source mode and sets a reactive power-voltage dead zone. The aggregation station control layer monitors the reactive power of each device in real time. If the reactive power of two devices is detected to be in opposite directions, the voltage reference value of one of them is adjusted until the reactive power circulation is eliminated. S104, a communication channel is established between the aggregation station control layer, the field station layer, and the network equipment. The communication channel allocates the calculated reactive power using the principle of overall allocation. The field station equipment feeds back the actual reactive power output and voltage value to the aggregation station control layer in real time through the communication channel. S105 When low voltage ride-through or high voltage ride-through is detected, the network-type equipment switches to transient support mode, prioritizes outputting the maximum reactive power current, and the collection station co-control layer suspends command transmission. After the voltage is restored, it re-enters the PV co-control mode.

2. The power regulation method for a new energy collection station according to claim 1, characterized in that, The specific steps for matching the capacity of grid-type equipment based on the location of the collection station include: dividing the collection station nodes into near-area weak grid nodes, load center nodes, and new energy rich nodes; calculating the multi-infeed short-circuit ratio of the collection station grid connection point, and increasing the capacity of grid-type equipment if the multi-infeed short-circuit ratio is less than a preset critical value; using electromagnetic transient simulation to simulate the peak value of bus overvoltage after a fault, and configuring more reactive power regulation equipment if the overvoltage exceeds 1.3 pu; the grid-type equipment includes grid-type SVG, grid-type energy storage, and static synchronous condenser.

3. The power regulation method for a new energy collection station according to claim 1, characterized in that, The PV mode refers to the external control characteristics of grid-connected equipment under normal operating conditions: constant active power and active setting and maintenance of voltage amplitude. Constant active power means that the equipment operates according to the scheduling plan and does not change its active power output due to voltage fluctuations. Active setting and maintenance of voltage amplitude means that the equipment acts as a voltage source, and its grid connection point voltage amplitude no longer passively follows the grid fluctuations. Instead, the equipment controller sets a reference value and adjusts the no-power output to make the actual voltage track the reference value.

4. The power regulation method for a new energy collection station according to claim 1, characterized in that, The formula for calculating total reactive power demand is: ,in, This represents the total non-regulating power demand at time t. This represents the voltage deviation at time t. This is the proportionality coefficient. The integral coefficient is... For the current moment, This is a virtual integral variable used in integral operations.

5. The power regulation method for a new energy collection station according to claim 4, characterized in that, The method for setting the reactive power-voltage dead zone is as follows: when the absolute value of the deviation between the grid connection point voltage and the rated value is less than 2%, the reactive power output of the grid-connected equipment is forcibly locked to the current value or zero; when the absolute value of the deviation is greater than or equal to 2%, the grid-connected equipment outputs reactive power according to the preset droop curve.

6. The power regulation method for a new energy collection station according to claim 1, characterized in that, Power regulation methods also include: S201 collects the grid connection point voltage, calculates the voltage deviation value based on the grid connection point voltage and the optimal voltage target value, and decomposes the voltage deviation value into low-frequency components and high-frequency components through a filter. S202, measure the frequency change rate at the grid connection point, construct a frequency-reactive power reverse channel based on the frequency change rate, output reactive power regulation amount from the frequency-reactive power reverse channel, and obtain reactive power reference value based on reactive power regulation amount, high frequency component and steady state base point. S203, based on the low-frequency component obtained by monitoring, compare the low-frequency component with a threshold. If the absolute value of the low-frequency component is greater than the preset threshold, perform on-load tap changer control and mechanical energy storage. S204 performs power regulation based on the reactive power reference value and the on-load tap changer control results.

7. The power regulation method for a new energy collection station according to claim 6, characterized in that, The method for constructing a frequency-reactive power reverse channel is as follows: The frequency change rate at the grid connection point is calculated in real time using a phase-locked loop (PLL), and then multiplied by a negative adaptive coefficient to obtain the reactive power regulation amount that is opposite to the direction of frequency change. ,in, Let be the reactive power adjustment at time t. The reverse coupling coefficient, This represents the rate of change of the frequency at which the equipment connects to the grid.

8. The power regulation method for a new energy collection station according to claim 7, characterized in that, The formula for calculating reactive power reference values ​​is: ,in, This is the reference value for the reactive power of the equipment. As the steady-state reactive power baseline, This is the voltage regulation coefficient. For high-frequency components, The reverse coupling coefficient, This represents the rate of change of the frequency at which the equipment connects to the grid.

9. A power regulation method for a new energy collection station according to claim 6, characterized in that, The on-load tap changer control includes: when the absolute value of the low-frequency component is greater than the threshold and the duration exceeds 30 seconds, determining the direction of action and sending an up or down command to the OLTC controller; 50ms before the OLTC action, sending a pre-compensation command to the SVG / energy storage to temporarily increase its output; and at the moment of OLTC switching, absorbing the reactive pulse released by the contact spring by reverse adjusting the output of the SVG / energy storage.

10. A power regulation method for a new energy collection station according to claim 6, characterized in that, The power regulation method further includes: S301, a distributed corona electrode array is formed by installing a ring-shaped corona electrode group on the conductor of the collection station; S302, based on the ion regulation voltage generated by the discharge of the distributed corona electrode array, the power is regulated by the voltage regulation result, and the regulation level of the voltage is matched and adjusted based on the voltage deviation value. The regulation level includes a fine adjustment layer, a medium adjustment layer and a coarse adjustment layer.

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