Active support control key parameter design method for improving new energy delivery capability

Abstract

The invention belongs to the technical field of power systems and automation thereof, provides an active support control key parameter design method for improving new energy delivery capacity, and provides a set of systematized improved overvoltage suppression strategies. According to the strategy, key parameters such as an optimal droop control coefficient and the like are systematically designed by constructing a composite evaluation index fusing reactive power-voltage sensitivity solved by an improved Jacobi matrix and transient voltage stability margin calculated based on a binary table method, and the defect that traditional parameter design depends on experience is overcome; and rapid and accurate suppression of the transient overvoltage of the LCC-HVDC rectification side is realized. As an infrastructure-friendly solution, the method fully utilizes existing equipment to provide reactive power support by optimizing an inherent control loop of the grid-connected inverter, and hardware compensation devices such as SVG do not need to be newly added, so that the investment cost is effectively reduced while the fault ride-through capability and the power transmission capacity of the system are remarkably improved, and the system reliability is improved. And the unification of high efficiency and economical efficiency is realized.

Description

Technical Field

[0001] This invention relates to the field of power systems and their automation technology, and in particular to a design method for key parameters of active support control to enhance the transmission capacity of new energy sources. Background Technology

[0002] In recent years, driven by the global trend of sustainable energy development, renewable energy power generation has made great progress. To achieve large-scale consumption of renewable energy, cross-regional power transmission has become an essential requirement. High-voltage direct current (HVDC) transmission technology plays a crucial role in this process due to its long-distance, high-capacity, and highly reliable power transmission capabilities.

[0003] Line commutated converter high voltage direct current (LCC-HVDC) transmission, as a widely used mainstream DC transmission technology, plays a crucial role in addressing key issues such as end-user consumption, grid dispatch, large-scale renewable energy grid integration, and inter-regional power transmission. However, the system faces a significant challenge: when a severe fault occurs in the AC system, commutation failure is likely to occur, potentially leading to a complete DC system shutdown. Under such conditions, reactive power is fed back into the AC grid, causing transient overvoltage problems on the rectifier side and severely limiting the system's transmission capacity.

[0004] Existing research on rectifier-side overvoltage suppression mainly revolves around three technical approaches: optimizing DC control systems, improving grid voltage stability margins, and using reactive power compensation devices for voltage regulation. Among these, effective suppression of AC overvoltage hinges on precise control of reactive power output. Some studies have proposed strengthening the AC grid structure on the rectifier side to address overvoltage, but this method requires additional coal-fired power units to support DC operation, which contradicts the clean energy development trend. Another approach uses a second-order Pade approximation algorithm to address the inherent delay in wind turbine voltage detection, achieving some success in reducing transient overvoltage peak values. However, this method lacks systematic optimization of the compensation coefficients and time steps, and the robustness of parameters to changes in grid strength has not been fully verified.

[0005] Furthermore, a study that quantifies the enhancement capabilities of devices such as SLCC, VSC, and SVG in the LCC-HVDC system using stability evaluation indicators shows that the enhancement effect of SVG under specific operating indicators exhibits rapid saturation, resulting in the ineffective utilization of its excess capacity and restricting the full realization of equipment efficiency. Summary of the Invention

[0006] Therefore, one objective of this invention is to propose a design method for key parameters of active support control to enhance the transmission capacity of new energy sources, so as to solve the problems mentioned in the background art and overcome the shortcomings of the prior art.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a method for designing key parameters of active support control to enhance the transmission capacity of new energy sources, comprising: The sensitivity between reactive power and AC voltage of the new energy subsystem of the high-voltage direct current transmission system of the grid-commutated converter is calculated based on the improved Jacobian matrix. The transient voltage stability margin is calculated based on the binary classification method, and a composite index for transient voltage stability assessment is constructed by combining the aforementioned sensitivity. The reciprocal of the composite index value calculated at the renewable energy access node is set as the droop coefficient of the renewable energy grid-connected inverter at that node. The key control parameters of the overvoltage fast suppression controller are designed based on the droop coefficient.

[0008] Preferably, the method further includes: A fault diagnosis module is constructed to monitor the AC voltage of the high-voltage DC transmission system of the grid phase converter in real time, and output a start signal when the voltage exceeds a preset threshold, and output a stop signal when the voltage returns to the normal operating range. An overvoltage fast suppression controller is constructed, which is put into operation in response to the start signal, controls the output reactive power of the renewable energy grid-connected system through key control parameters to suppress transient overvoltage, and exits operation in response to the exit signal.

[0009] Preferably, the improved Jacobian matrix is ​​obtained through the following steps: An improved power flow calculation model incorporating the power equations of a permanent magnet synchronous wind turbine and a photovoltaic power generation system is constructed, and its expression is as follows: ; in, This refers to the active power generated by the generator. This represents the voltage magnitude at node i. Let J be the voltage magnitude at node j. Let be the real part of the element in the i-th row and j-th column of the nodal admittance matrix. Represents the imaginary part of the element in the i-th row and j-th column of the nodal admittance matrix; Let i be the voltage phase difference between node i and node j. This refers to the reactive power generated by the generator. By performing differential derivation on the improved power flow calculation model, the improved Jacobian matrix is ​​obtained: ; in, and These are the incremental change vectors of active power and reactive power, respectively. and These are the incremental change vectors of the commutation voltage angle and voltage amplitude, respectively; For the complete improved Jacobian matrix, and can be determined according to the selected state variables. Divide U into four sub-matrices ( , , , ).

[0010] Preferably, the sensitivity is a submatrix of the aforementioned improved Jacobian matrix. The decision is made using the following formula: ; in, Let J be the voltage magnitude at node j. Let be the reactive power flowing into node j.

[0011] Preferably, the transient voltage stability margin The calculation formula is: ; in, The threshold for overvoltage. The threshold for low voltage. As an evaluation index for overvoltage, As an evaluation indicator for low voltage, The time during which the voltage is allowed to exceed the threshold. This is the reference value for the rated voltage. - The recovery time of the overvoltage state quantity. - This refers to the recovery time of a quantity under low voltage conditions.

[0012] Preferably, the overvoltage fast suppression controller implements control by adjusting the droop control coefficients of the permanent magnet synchronous wind turbine and the photovoltaic inverter, wherein: The reactive power output of the permanent magnet synchronous wind turbine meets the following requirements: ; in, This refers to the reactive power of a permanent magnet synchronous wind turbine generator. This refers to the rated reactive power of a permanent magnet synchronous wind turbine generator. This refers to the droop control coefficient in the grid-side converter control of permanent magnet synchronous wind turbine generators. This is the measured voltage value at the common coupling point of the permanent magnet synchronous generator; This refers to the rated voltage at the common connection point of the permanent magnet synchronous wind turbine generator. The reactive power output of the photovoltaic inverter meets the following requirements: ; in, The reactive power generated by the photovoltaic power generation system. The rated reactive power of the photovoltaic power generation system. This is the droop control coefficient in photovoltaic converter control. This is the measured voltage value at the point of common coupling of the photovoltaic power generation system. This refers to the rated voltage at the point of common coupling of the photovoltaic power generation system.

[0013] Preferably, the composite index The expression is as follows: ; in, Transient voltage stability margin for each node, Let J be the voltage magnitude at node j. Let be the reactive power flowing into node j.

[0014] Secondly, the present invention provides a design system for key parameters of active support control to enhance the transmission capacity of new energy sources, comprising: The sensitivity determination module is used to calculate the sensitivity between the reactive power of the grid-commutated converter high-voltage DC transmission system and the AC voltage of the new energy subsystem based on the improved Jacobian matrix. The composite index determination module is used to calculate the transient voltage stability margin based on the binary classification method, and to construct a composite index for transient voltage stability assessment in combination with the sensitivity. The droop coefficient determination module is used to set the reciprocal of the composite index value calculated at the renewable energy access node as the droop coefficient of the renewable energy grid-connected inverter at that node. The key control parameter design module is used to design the key control parameters of the overvoltage fast suppression controller based on the droop coefficient. The fault diagnosis module is used to monitor the AC voltage of the high voltage DC transmission system of the grid commutator in real time, and output a start signal when the voltage exceeds a preset threshold, and output a stop signal when the voltage returns to the normal operating range. An overvoltage fast suppression controller is used to activate in response to the start signal, control the output reactive power of the renewable energy grid-connected system through key control parameters to suppress transient overvoltage, and deactivate in response to the exit signal.

[0015] Preferably, the improved Jacobian matrix is ​​obtained through the following steps: An improved power flow calculation model incorporating the power equations of a permanent magnet synchronous wind turbine and a photovoltaic power generation system is constructed, and its expression is as follows: ; in, This refers to the active power generated by the generator. This represents the voltage magnitude at node i. Let J be the voltage magnitude at node j. Let be the real part of the element in the i-th row and j-th column of the nodal admittance matrix. Represents the imaginary part of the element in the i-th row and j-th column of the nodal admittance matrix; Let i be the voltage phase difference between node i and node j. This refers to the reactive power generated by the generator. By performing differential derivation on the improved power flow calculation model, the improved Jacobian matrix is ​​obtained: ; in, and These are the incremental change vectors of active power and reactive power, respectively. and These are the incremental change vectors of the commutation voltage angle and voltage amplitude, respectively; For the complete improved Jacobian matrix, and can be determined according to the selected state variables. Divide U into four sub-matrices ( , , , ).

[0016] Preferably, the sensitivity is a submatrix of the aforementioned improved Jacobian matrix. The decision is made using the following formula: ; in, Let J be the voltage magnitude at node j. Let be the reactive power flowing into node j.

[0017] Preferably, the transient voltage stability margin The calculation formula is: ; in, The threshold for overvoltage. The threshold for low voltage. As an evaluation index for overvoltage, As an evaluation indicator for low voltage, The time during which the voltage is allowed to exceed the threshold. This is the reference value for the rated voltage. - The recovery time of the overvoltage state quantity. - This refers to the recovery time of a quantity under low voltage conditions.

[0018] Preferably, the overvoltage fast suppression controller implements control by adjusting the droop control coefficients of the permanent magnet synchronous wind turbine and the photovoltaic inverter, wherein: The reactive power output of the permanent magnet synchronous wind turbine meets the following requirements: ; in, This refers to the reactive power of a permanent magnet synchronous wind turbine generator. This refers to the rated reactive power of a permanent magnet synchronous wind turbine generator. This refers to the droop control coefficient in the grid-side converter control of permanent magnet synchronous wind turbine generators. This is the measured voltage value at the common coupling point of the permanent magnet synchronous generator; This refers to the rated voltage at the common connection point of the permanent magnet synchronous wind turbine generator. The reactive power output of the photovoltaic inverter meets the following requirements: ; in, The reactive power generated by the photovoltaic power generation system. The rated reactive power of the photovoltaic power generation system. This is the droop control coefficient in photovoltaic converter control. This is the measured voltage value at the point of common coupling of the photovoltaic power generation system. This refers to the rated voltage at the point of common coupling of the photovoltaic power generation system.

[0019] Preferably, the composite index The expression is as follows: ; in, Transient voltage stability margin for each node, Let J be the voltage magnitude at node j. Let be the reactive power flowing into node j.

[0020] Thirdly, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described method for designing key parameters of active support control to enhance the transmission capacity of new energy sources.

[0021] Fourthly, the present invention provides a readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, it implements the steps of the above-described method for designing key parameters of active support control to enhance the transmission capacity of new energy sources.

[0022] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: This invention provides a design method for key parameters of active support control to enhance the transmission capacity of new energy sources. By constructing quantitative indicators of transmission capacity applicable to new energy sources via high-voltage direct current transmission systems, the method includes reactive power-voltage sensitivity solved by an improved Jacobian matrix and transient voltage stability margin solved by a binary classification method. The method systematically calculates the optimal droop control coefficient and transient voltage stability margin that reflect reactive power and voltage sensitivity, overcoming the problems of parameter dependence on experience or lack of systematic optimization in traditional schemes, and achieving accurate and robust design of key control parameters.

[0023] This invention is based on transient voltage stability assessment and coordinated control using a composite index. It innovatively combines reactive power-voltage sensitivity derived from an improved Jacobian matrix with transient voltage stability margin determined by a binary classification method to establish a composite assessment index. This index is directly used to guide the activation and deactivation of the improved overvoltage suppression strategy (IOSS) and optimize its control effect, thereby achieving rapid and accurate suppression of transient overvoltage on the LCC-HVDC rectifier side under severe faults such as commutation failure or DC blockage.

[0024] This invention, as a control strategy and parameter design method, optimizes the inherent control loop of grid-connected inverters (such as permanent magnet synchronous wind turbines and photovoltaic inverters), making full use of existing equipment to provide reactive power support without relying on additional reactive power compensation devices (such as SVG) or strengthening the power grid structure. It effectively solves the problems of insufficient equipment capacity utilization, contradiction with the development orientation of clean energy, or high investment costs in the prior art, and significantly improves the system's fault ride-through capability and transmission capacity.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A flowchart illustrating a method for designing key parameters of active support control to enhance the transmission capacity of new energy sources, according to an embodiment of the present invention. Figure 2This is an equivalent structure diagram of a renewable energy source based on high-voltage direct current transmission according to an embodiment of the present invention; Figure 3 This is a block diagram of IOSS according to an embodiment of the present invention; Figure 4 This is a diagram of a renewable energy topology based on high-voltage direct current transmission according to an embodiment of the present invention; Figure 5 This is a graph showing the calculation results of the comprehensive evaluation index of DC transmission capacity according to an embodiment of the present invention; Figure 6 This is a voltage change curve during DC blocking according to an embodiment of the present invention; Figure 7 This is a voltage change curve when commutation fails according to an embodiment of the present invention; Figure 8 The graphs show the fault voltage variation under different control strategies in this embodiment of the invention. Figure 9 The graphs show the DC transmission capacity curves under different control strategies according to embodiments of the present invention. Figure 10 This is a graph showing the reactive power support capability under different control strategies in an embodiment of the present invention. Figure 11 This is a schematic diagram of a key parameter design system for active support control to enhance the transmission capacity of new energy sources, according to an embodiment of the present invention. Figure 12 This is a schematic block diagram of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] like Figure 2 The diagram illustrates a topology for a new energy source via a high-voltage direct current (HVDC) transmission system. This system comprises synchronous generators, a renewable energy grid-connected system, and a grid-commutated converter HVDC link. The LCC-HVDC link is constructed as a 24-pulse structure according to the International Conference on Large Electric Systems (CIGRE) standard, and its filters and reactive power compensation devices are represented by parallel-connected equivalent grounding susceptance. The renewable energy generation component includes permanent magnet synchronous generators and photovoltaic power generation systems, both of which are grid-connected via voltage source converters. These grid-connected inverters employ a control strategy based on d-axis control of DC voltage and q-axis control of reactive power. A key operational challenge for this system is the potential for overvoltage on the rectifier-side AC bus following commutation failure or DC blocking faults.

[0029] Based on this, such as Figure 1 As shown, this invention proposes a design method for key parameters of active support control to improve the transmission capacity of new energy sources. This method mainly includes the calculation of parameters for the overvoltage fast suppression controller and related numerical calculations for the fault diagnosis module. The calculation of the overvoltage fast suppression controller parameters is primarily obtained by calculating the reactive power sensitivity of the LCC subsystem and the AC voltage sensitivity of the new energy subsystem using an improved Jacobian matrix. It includes the following steps: The sensitivity between reactive power and AC voltage of the new energy subsystem of the high-voltage direct current transmission system of the grid-commutated converter is calculated based on the improved Jacobian matrix. The transient voltage stability margin is calculated based on the binary classification method, and a composite index for transient voltage stability assessment is constructed by combining the aforementioned sensitivity. The reciprocal of the composite index value calculated at the renewable energy access node is set as the droop coefficient of the renewable energy grid-connected inverter at that node. The key control parameters of the overvoltage fast suppression controller are designed based on the droop coefficient.

[0030] Furthermore, it also includes: A fault diagnosis module is constructed to monitor the AC voltage of the high-voltage DC transmission system of the grid phase converter in real time, and output a start signal to the selector when the voltage exceeds a preset threshold, and output an exit / stop signal to the selector when the voltage returns to the normal operating range. An overvoltage fast suppression controller is constructed, which is put into operation in response to the start signal, controls the output reactive power of the renewable energy grid-connected system through key control parameters to suppress transient overvoltage, and exits / stops operation in response to the exit / stop signal.

[0031] like Figure 3 As shown, the improved overvoltage suppression strategy (IOSS) includes a fault diagnosis module (FDM) and an overvoltage fast suppression controller (OFSC). The control logic for mitigating AC bus overvoltage operates as follows: When the fault diagnosis module detects that the AC line voltage exceeds a preset threshold, the voltage data of the renewable energy grid-connected inverter is transmitted to the IOSS system, automatically activating the overvoltage fast suppression controller. The activation of this controller effectively suppresses overvoltage phenomena on the LCC-HVDC rectifier side bus. When the fault diagnosis module detects that the system voltage has returned to the normal operating range, the overvoltage fast suppression controller automatically exits operation.

[0032] Furthermore, under stable operating conditions, the reactive power demand of the LCC-HVDC converter station is mainly compensated by the reactive power provided by the filters. However, when a commutation failure occurs, an overvoltage phenomenon will appear on the rectifier side. The quantitative relationship between voltage and reactive power under this fault condition is characterized by the following formula: ; in, , These represent the active power and reactive power injected into the grid-connected phase-commutator high-voltage direct current transmission (LCC-HVDC) system, respectively. It is the active power transmitted through DC lines; It is the dimensionless voltage value measured at the point of common coupling (PCC); The rated reactive power generated by the RPCD The reactive power consumed by the LCC-HVDC converter.

[0033] Furthermore, by introducing a reactive power control strategy into the droop control mechanism, the renewable energy grid-connected system can provide a specific amount of reactive power during AC grid faults, thereby ensuring sufficient voltage support. Correspondingly, the relationship between power and voltage amplitude at the port of a permanent magnet direct-drive synchronous wind turbine (PMSG) is characterized by the following formula: ; In the formula, , These represent the active power and reactive power generated by the permanent magnet synchronous wind turbine (PMSG), respectively. This refers to the rated reactive power of a permanent magnet synchronous wind turbine generator. This represents the equivalent impedance of a permanent magnet synchronous generator. This is the voltage phase angle difference; It is the droop control coefficient in the grid-side converter control of permanent magnet synchronous wind turbine generator; This represents the measured voltage value at the point of common coupling (PCC) of the permanent magnet synchronous generator; This refers to the rated voltage at the point of common coupling (PCC) of the permanent magnet synchronous wind turbine.

[0034] Furthermore, the relationship between power and voltage at the photovoltaic inverter port is characterized by the following formula: ; In the formula: , These represent the active power and reactive power generated by the photovoltaic power generation system, respectively. The rated reactive power of the photovoltaic power generation system; This represents the equivalent impedance of a photovoltaic power generation system; This is the voltage phase angle difference; It is the droop control coefficient in photovoltaic converter control; This indicates the measured voltage value at the point of common coupling (PCC) of the photovoltaic power generation system; This refers to the rated voltage value of the photovoltaic power generation system.

[0035] Furthermore, by integrating the power equations of each subsystem into a multi-node power flow calculation framework, an improved power flow calculation method suitable for new energy transmission systems via high-voltage direct current (HVDC) is constructed: ; In the formula: This indicates the active power output of the generator; This represents the voltage magnitude at node j; This indicates the reactive power output of the generator; This represents the voltage magnitude at node i; Let be the real part of the element in the i-th row and j-th column of the node admittance matrix; Represents the imaginary part of the element in the i-th row and j-th column of the nodal admittance matrix; Let be the voltage phase difference between node i and node j.

[0036] Furthermore, for renewable energy high-voltage direct current transmission systems, an improved Jacobian matrix is ​​obtained through differential derivation of the improved power flow calculation formula, and its mathematical expression is as follows: ; In the formula: and These are the incremental change vectors of active power and reactive power, respectively. and These are the incremental change vectors of the commutation voltage angle and voltage amplitude, respectively; For a complete improved Jacobian matrix, and can be determined based on selected state variables (phase angles) The amplitude U) is divided into four sub-matrices ( , , , ).

[0037] Furthermore, the droop coefficient k represents the sensitivity between reactive power and AC voltage amplitude in LCC-HVDC (grid-commutated high-voltage direct current transmission) under renewable energy scenarios. The formula for calculating the droop coefficient is derived.

[0038] ; in, is the voltage amplitude at node j, and k is the droop coefficient in converter control. It is the reactive power flowing into node j.

[0039] Furthermore, to assess transient voltage stability margin, a binary classification method is used for renewable energy systems connected to the grid via high-voltage direct current (HVDC) transmission. This criterion defines system instability as a transient voltage deviation exceeding 0.8–1.2 pu and lasting for more than 1.0 s.

[0040] ; In the formula, It represents the transient voltage margin of each node. The overvoltage threshold; The threshold voltage refers to the low voltage level. This refers to the evaluation index for overvoltage; This refers to the evaluation criteria for low voltage; This refers to the time during which the voltage is allowed to exceed a threshold. The state quantity based on the binary table criterion exceeds the maximum allowable value of the rated voltage; This represents the maximum allowable value for the cumulative drop in state variables based on the binary table criterion. This is the reference value for the rated voltage. and These are the states that fall below during the process of state quantity drop. and higher during the recovery process At that moment, - This is the recovery time for the overvoltage condition. - This refers to the recovery time of a quantity under low voltage conditions.

[0041] Furthermore, by combining reactive power-voltage sensitivity with the transient voltage margin obtained from the binary classification method, a proposed composite index for transient voltage stability assessment was established: ; In the formula, It represents the transient voltage margin of each node.

[0042] In one embodiment, to verify the effectiveness of IOSS, a renewable energy system based on high-voltage direct current transmission was built in PSCAD / EMTDC, such as... Figure 4As shown in the figure, this model is constructed based on the specific topology of the Northwest my country Power Grid and is used to characterize a renewable energy system based on high-voltage direct current (HVDC). The system model includes a HVDC transmission system, photovoltaic and wind power generation systems, energy storage systems, hydropower, and other equivalent grid nodes. The LCC-HVDC system uses a 24-pulse converter conforming to the CIGRE standard. The rated capacity of this HVDC transmission system is 6000MW, the DC voltage is ±800kV, the DC current is 7.5kA, and it is connected to a 750kV AC grid. Analysis and comparison were conducted for different fault scenarios. Case A: A three-phase ground fault lasting 0.1 seconds was set on the inverter side, causing the system to fail to commutate; Case B: A ground fault lasting 0.1 seconds was set on a DC line, causing DC blocking.

[0043] In this embodiment, the operating condition after a commutation failure was simulated, and the transient voltage stability margin was calculated. For example... Figure 5 As shown, η values ​​greater than 3 were observed at renewable energy access nodes III, V, and VIII, indicating poor DC stability and limited transmission capacity in this region. Figure 4 As can be seen, Node III connects both the LCC-HVDC transmission line and a large-capacity renewable energy generation system, while Nodes V and VIII are connected to large-scale renewable energy generation units. Analysis shows that the main reason for the deterioration in voltage stability is that the inertial support provided by the LCC-HVDC system and the photovoltaic system is close to zero.

[0044] In this embodiment, simulation verification of different faults is conducted. To enhance voltage stability, this invention introduces reactive power-voltage droop control in the grid-connected inverter of the renewable energy system. This control strategy achieves voltage stability regulation by setting the reciprocal of the η value of each corresponding node as the droop coefficient. Figure 6 and Figure 7 As shown, simulation results comparing control performance under commutation failure and DC blockage faults demonstrate that the proposed droop control most effectively suppresses voltage fluctuations. This invention uses the minimum reactive voltage sag factor as the benchmark for comparison of the proposed control strategy, i.e., setting the droop control factor to 1.5.

[0045] like Figures 8-10 As shown in the simulation verification of transmission capacity in this embodiment, the peak transient voltage is set as a constant comparison benchmark under fault conditions. Analysis indicates that after adopting the optimized control strategy, the maximum transmission power increases from 6000MW to 6690MW, a relative increase of 11.5%. This scheme significantly enhances reactive power support capability.

[0046] This invention proposes a design method for key parameters of active support control to enhance the transmission capacity of new energy sources. Its innovations and core protection points are mainly reflected in the following aspects: An Improved Overvoltage Suppression Strategy (IOSS) and Key Parameter Design Method: This paper proposes a systematic solution including a Fault Diagnosis Module (FDM) and an Overvoltage Fast Suppression Controller (OFSC). Its core innovation lies in constructing a quantitative index suitable for the transmission capacity of new energy sources via HVDC transmission systems. This index includes reactive power-voltage sensitivity solved using an improved Jacobian matrix and a transient voltage stability margin calculation method based on a binary table method. The optimal droop control coefficient (k) reflecting reactive power and voltage sensitivity, as well as the transient voltage stability margin value, are systematically calculated. This method overcomes the problems of parameter dependence on experience or lack of systematic optimization in traditional schemes, achieving accurate and robust design of key control parameters.

[0047] Transient Voltage Stability Assessment and Coordinated Control Based on Composite Indicators: This innovative approach combines reactive power-voltage sensitivity derived from an improved Jacobian matrix with transient voltage stability margin determined by a binary classification method to establish a composite assessment index. This index directly guides the startup and shutdown of IOSS (Inverterless Supersonic Oscillator) and optimizes its control performance, thereby achieving rapid and precise suppression of transient overvoltages on the LCC-HVDC rectifier side under severe faults such as commutation failure or DC blockage.

[0048] Infrastructure-friendly solution requiring no additional hardware: The core protection of this solution lies in its role as a control strategy and parameter design method. By optimizing the inherent control loop of grid-connected inverters (such as permanent magnet synchronous wind turbines and photovoltaic inverters), it fully utilizes existing equipment to provide reactive power support without relying on additional reactive power compensation devices (such as SVG) or strengthening the grid structure. This effectively solves the problems of insufficient equipment capacity utilization, contradiction with the development orientation of clean energy, or high investment costs in existing technologies, and significantly improves the system's fault ride-through capability and transmission capacity.

[0049] This invention also provides a design system for key parameters of active support control to enhance the transmission capacity of new energy sources, such as... Figure 11 As shown, it includes: The sensitivity determination module is used to calculate the sensitivity between the reactive power of the grid-commutated converter high-voltage DC transmission system and the AC voltage of the new energy subsystem based on the improved Jacobian matrix. The composite index determination module is used to calculate the transient voltage stability margin based on the binary classification method, and to construct a composite index for transient voltage stability assessment in combination with the sensitivity. The droop coefficient determination module is used to set the reciprocal of the composite index value calculated at the renewable energy access node as the droop coefficient of the renewable energy grid-connected inverter at that node. The key control parameter design module is used to design the key control parameters of the overvoltage fast suppression controller based on the droop coefficient. The fault diagnosis module is used to monitor the AC voltage of the high voltage DC transmission system of the grid commutator converter in real time, and output a start signal when the voltage exceeds a preset threshold, and output an exit / stop signal when the voltage returns to the normal operating range. An overvoltage fast suppression controller is used to activate the system in response to the start signal, control the output reactive power of the renewable energy grid-connected system through key control parameters to suppress transient overvoltage, and to deactivate / stop the system in response to the exit / stop signal.

[0050] Furthermore, the improved Jacobian matrix is ​​obtained through the following steps: An improved power flow calculation model incorporating the power equations of a permanent magnet synchronous wind turbine and a photovoltaic power generation system is constructed, and its expression is as follows: ; in, This refers to the active power generated by the generator. This represents the voltage magnitude at node i. Let J be the voltage magnitude at node j. Let be the real part of the element in the i-th row and j-th column of the nodal admittance matrix. Represents the imaginary part of the element in the i-th row and j-th column of the nodal admittance matrix; Let i be the voltage phase difference between node i and node j. This refers to the reactive power generated by the generator. By performing differential derivation on the improved power flow calculation model, the improved Jacobian matrix is ​​obtained: ; in, and These are the incremental change vectors of active power and reactive power, respectively. and These are the incremental change vectors of the commutation voltage angle and voltage amplitude, respectively; For the complete improved Jacobian matrix, and can be determined according to the selected state variables. Divide U into four sub-matrices ( , , , ).

[0051] Furthermore, the sensitivity is determined by a submatrix of the aforementioned improved Jacobian matrix. The decision is made using the following formula: ; in, Let J be the voltage magnitude at node j. Let be the reactive power flowing into node j.

[0052] Furthermore, the transient voltage stability margin The calculation formula is: ; in, The threshold for overvoltage. The threshold for low voltage. As an evaluation index for overvoltage, As an evaluation indicator for low voltage, The time during which the voltage is allowed to exceed the threshold. This is the reference value for the rated voltage. - The recovery time of the overvoltage state quantity. - This refers to the recovery time of a quantity under low voltage conditions.

[0053] Furthermore, the overvoltage fast suppression controller implements control by adjusting the droop control coefficients of the permanent magnet synchronous wind turbine and the photovoltaic inverter, wherein: The reactive power output of the permanent magnet synchronous wind turbine meets the following requirements: ; in, This refers to the reactive power of a permanent magnet synchronous wind turbine generator. This refers to the rated reactive power of a permanent magnet synchronous wind turbine generator. This refers to the droop control coefficient in the grid-side converter control of permanent magnet synchronous wind turbine generators. This is the measured voltage value at the common coupling point of the permanent magnet synchronous generator; This refers to the rated voltage at the common connection point of the permanent magnet synchronous wind turbine generator. The reactive power output of the photovoltaic inverter meets the following requirements: ; in, The reactive power generated by the photovoltaic power generation system. The rated reactive power of the photovoltaic power generation system. This is the droop control coefficient in photovoltaic converter control. This is the measured voltage value at the point of common coupling of the photovoltaic power generation system. This refers to the rated voltage at the point of common coupling of the photovoltaic power generation system.

[0054] Furthermore, the composite index The expression is as follows: ; in, Transient voltage stability margin for each node, Let J be the voltage magnitude at node j. Let be the reactive power flowing into node j.

[0055] It should be understood that, since the above-described modules are merely for illustrating the functional units of the system disclosed herein, the physical devices corresponding to these modules may be the processor itself, or a part of the processor's software, hardware, or a combination of both. Therefore, the number of modules shown in the figures is merely illustrative.

[0056] To address the aforementioned technical problems, this invention also provides a computer / electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of the above-described method for designing key parameters of active support control to enhance the transmission capacity of new energy sources.

[0057] like Figure 12 As shown, the computer / electronic device includes memory, processor, and network interface interconnected via a system bus. It should be noted that the figure only shows a computer device with components such as memory, processor, network interface, and operating system; however, it should be understood that it is not required to implement all the components shown, and more or fewer components can be implemented alternatively. Those skilled in the art will understand that the computer / electronic device described here is a device capable of automatically performing numerical calculations and / or information processing according to pre-set or stored instructions, and its hardware includes, but is not limited to, microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), embedded devices, etc.

[0058] Computers / electronic devices can be desktop computers, laptops, PDAs, and cloud servers, among other computing devices. They can interact with users through keyboards, mice, remote controls, touchpads, or voice-activated devices.

[0059] There may be one or more memories, and at least one type of readable storage medium, including flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, etc. In some embodiments, the memory may be an internal storage unit of a computer device, such as the hard disk or RAM of the computer device. In other embodiments, the memory may also be an external storage device of the computer device, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the computer device. Of course, the memory may include both internal storage units and external storage devices of the computer device. In this embodiment, the memory is typically used to store the operating system and various application software installed on the computer device, such as program code for a method for designing key parameters of active support control to improve the transmission capacity of new energy sources. In addition, the memory may also be used to temporarily store various types of data that have been output or will be output.

[0060] In some embodiments, the processor may be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip. The processor is typically used to control the overall operation of a computer device. In this embodiment, the processor is used to run program code stored in memory or process data, such as running program code for a method to design key parameters for active support control to improve the transmission capacity of new energy sources.

[0061] Network interfaces may include wireless network interfaces and / or wired network interfaces, which are typically used to establish communication connections between computer devices and other electronic devices.

[0062] The present invention also provides another embodiment, namely, providing a readable storage medium on which a computer program is stored, which, when executed by a processor, implements the steps of the above-described method for designing key parameters of active support control to enhance the transmission capacity of new energy sources.

[0063] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] It will be readily understood by those skilled in the art that this invention includes any combination of the inventive description and specific embodiments outlined in the foregoing specification, as well as the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0065] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for designing key parameters of active support control to enhance the transmission capacity of new energy sources, characterized in that, include: The sensitivity between reactive power and AC voltage of the new energy subsystem of the high-voltage direct current transmission system of the grid-commutated converter is calculated based on the improved Jacobian matrix. The transient voltage stability margin is calculated based on the binary classification method, and a composite index for transient voltage stability assessment is constructed by combining the aforementioned sensitivity. The reciprocal of the composite index value calculated at the renewable energy access node is set as the droop coefficient of the renewable energy grid-connected inverter at that node. The key control parameters of the overvoltage fast suppression controller are designed based on the droop coefficient.

2. The design method for key parameters of active support control for improving new energy transmission capacity as described in claim 1, characterized in that, Also includes: A fault diagnosis module is constructed to monitor the AC voltage of the high-voltage DC transmission system of the grid phase converter in real time, and output a start signal when the voltage exceeds a preset threshold, and output a stop signal when the voltage returns to the normal operating range. An overvoltage fast suppression controller is constructed, which is put into operation in response to the start signal, controls the output reactive power of the renewable energy grid-connected system through key control parameters to suppress transient overvoltage, and exits operation in response to the exit signal.

3. The design method for key parameters of active support control for improving the transmission capacity of new energy sources as described in claim 1, characterized in that, The improved Jacobian matrix is ​​obtained through the following steps: An improved power flow calculation model incorporating the power equations of a permanent magnet synchronous wind turbine and a photovoltaic power generation system is constructed, and its expression is as follows: ； in, This refers to the active power generated by the generator. This represents the voltage magnitude at node i. Let J be the voltage magnitude at node j. Let be the real part of the element in the i-th row and j-th column of the nodal admittance matrix. Represents the imaginary part of the element in the i-th row and j-th column of the nodal admittance matrix; Let i be the voltage phase difference between node i and node j. This refers to the reactive power generated by the generator. By performing differential derivation on the improved power flow calculation model, the improved Jacobian matrix is ​​obtained: ； in, and These are the incremental change vectors of active power and reactive power, respectively. and These are the incremental change vectors of the commutation voltage angle and voltage amplitude, respectively; For the complete improved Jacobian matrix, and can be determined according to the selected state variables. Divide U into four sub-matrices ( , , , ).

4. The design method for key parameters of active support control for improving the transmission capacity of new energy sources as described in claim 3, characterized in that, The sensitivity is determined by a submatrix of the improved Jacobian matrix. The decision is made using the following formula: ； in, Let J be the voltage magnitude at node j. Let be the reactive power flowing into node j.

5. The design method for key parameters of active support control for improving the transmission capacity of new energy sources as described in claim 1, characterized in that, The transient voltage stability margin The calculation formula is: ； in, The threshold for overvoltage. The threshold for low voltage. As an evaluation index for overvoltage, As an evaluation indicator for low voltage, The time during which the voltage is allowed to exceed the threshold. This is the reference value for the rated voltage. - The recovery time of the overvoltage state quantity. - This refers to the recovery time of a quantity under low voltage conditions.

6. The design method for key parameters of active support control for improving the transmission capacity of new energy sources as described in claim 2, characterized in that, The overvoltage fast suppression controller implements control by adjusting the droop control coefficients of the permanent magnet synchronous wind turbine and the photovoltaic inverter, wherein: The reactive power output of the permanent magnet synchronous wind turbine meets the following requirements: ； in, This refers to the reactive power of a permanent magnet synchronous wind turbine generator. This refers to the rated reactive power of a permanent magnet synchronous wind turbine generator. This refers to the droop control coefficient in the grid-side converter control of permanent magnet synchronous wind turbine generators. This is the measured voltage value at the common coupling point of the permanent magnet synchronous generator; This refers to the rated voltage at the common connection point of the permanent magnet synchronous wind turbine generator. The reactive power output of the photovoltaic inverter meets the following requirements: ； in, The reactive power generated by the photovoltaic power generation system. The rated reactive power of the photovoltaic power generation system. This is the droop control coefficient in photovoltaic converter control. This is the measured voltage value at the point of common coupling of the photovoltaic power generation system. This refers to the rated voltage at the point of common coupling of the photovoltaic power generation system.

7. The design method for key parameters of active support control for improving new energy transmission capacity as described in claim 1, characterized in that, The composite index The expression is as follows: ； in, Transient voltage stability margin for each node, Let J be the voltage magnitude at node j. Let be the reactive power flowing into node j.

8. A design system for key parameters of active support control to enhance the transmission capacity of new energy sources, characterized in that, include: The sensitivity determination module is used to calculate the sensitivity between the reactive power of the grid-commutated converter high-voltage DC transmission system and the AC voltage of the new energy subsystem based on the improved Jacobian matrix. The composite index determination module is used to calculate the transient voltage stability margin based on the binary classification method, and to construct a composite index for transient voltage stability assessment in combination with the sensitivity. The droop coefficient determination module is used to set the reciprocal of the composite index value calculated at the renewable energy access node as the droop coefficient of the renewable energy grid-connected inverter at that node. The key control parameter design module is used to design the key control parameters of the overvoltage fast suppression controller based on the droop coefficient. The fault diagnosis module is used to monitor the AC voltage of the high-voltage DC transmission system of the grid phase converter in real time, and output a start signal when the voltage exceeds a preset threshold, and output an exit signal when the voltage returns to the normal operating range. An overvoltage fast suppression controller is used to activate the system in response to the start signal, control the output reactive power of the renewable energy grid-connected system through key control parameters to suppress transient overvoltages, and deactivate the system in response to the exit signal.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the active support control key parameter design method for improving the new energy transmission capacity as described in claims 1-7.

10. A readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the active support control key parameter design method for improving the transmission capacity of new energy sources as described in claims 1-7.

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