Method and device for controlling surplus power consumption of island new energy system

Abstract

The invention relates to the technical field of high-voltage direct-current power transmission, and discloses a surplus power consumption control method and device for an island new energy system, and the method comprises the steps: monitoring the output energy and direct-current link voltage of a transmitting-end converter station, and carrying out the control of the surplus power consumption when the island new energy system has an alternating-current fault; controlling the receiving-end converter station to perform optimal distribution of receiving-end current and dynamic adjustment of a direct-current voltage reference value so as to preferentially absorb surplus power, and further raising output energy and direct-current link voltage; when it is detected that the output energy meets the energy requirement and the direct-current link voltage meets the voltage requirement, the sending-end converter station is controlled to correct an energy reference value so that the sending-end converter station can consume surplus power through new energy, and after the alternating-current fault is removed, the sending-end converter station and the receiving-end converter station are controlled to perform sequential energy release so that the surplus power can be eliminated. When the energy consumption device is not used, the consumption control of the surplus power of the system is realized through cooperative inertia response and sequential energy release.

Description

Technical Field

[0001] This invention relates to the field of high-voltage direct current transmission technology, and in particular to a method and apparatus for controlling the surplus power absorption of an isolated renewable energy system. Background Technology

[0002] Modular multilevel converter-based high-voltage direct current (MMC-HVDC) technology is increasingly being applied to isolated renewable energy grid-connected projects. When an AC fault occurs in the system, causing power transmission to be blocked, the isolated renewable energy MMC-HVDC system suffers from overvoltage problems due to the limited power dissipation capacity on the AC side. This can easily lead to overvoltage lockout of the converter valve, significantly impacting the safe and stable operation of the system.

[0003] Currently, the main methods for dissipating surplus power in MMC-HVDC systems are reducing renewable energy output and system dissipation. Reducing renewable energy output primarily involves communication methods, voltage reduction methods, and frequency upscaling methods. However, these strategies suffer from problems such as low communication reliability, overcurrent in the grid-side converter of the wind turbine, and limited reduction in active power. The latter two also have the drawback of slow response speed. System dissipation is divided into AC energy-consuming devices and DC energy-consuming devices, such as full-bridge flexible energy-consuming devices and high-frequency buffer strategies suitable for large-capacity DC energy-consuming devices. While these can reduce losses without affecting the normal output of renewable energy plants, they also dissipate surplus power as heat during each fault, resulting in a certain degree of energy waste. Furthermore, the construction cost of these energy-consuming devices is high, leading to poor economic efficiency in engineering costs.

[0004] Therefore, it is evident that proposing a surplus power consumption strategy for isolated renewable energy systems that does not rely on energy-consuming devices, while considering reducing the use of energy-consuming devices and further improving the system's surplus power utilization capacity, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a method and apparatus for controlling surplus power absorption in an isolated renewable energy system, addressing the problem of how to propose a surplus power absorption strategy for an isolated renewable energy system that does not rely on energy-consuming devices, thereby further improving the system's surplus power utilization capacity while considering reducing the use of energy-consuming devices.

[0006] To address the aforementioned technical problems, the first aspect of this invention provides a method for controlling surplus power absorption in an isolated renewable energy system. The isolated renewable energy system is a high-voltage direct current transmission system based on a modular multilevel converter, comprising a sending-end converter station and a receiving-end converter station. The method includes: Real-time monitoring of the output energy and DC link voltage of the sending-end converter station; When an AC fault is detected in the isolated renewable energy system, the receiving-end converter station is controlled to optimize the allocation of the receiving-end current and dynamically adjust its DC voltage reference value based on the output energy, so that the receiving-end converter station increases the output energy and the DC link voltage according to the obtained allocation and adjustment results. When the output energy reaches a preset energy threshold and the DC link voltage reaches a preset voltage threshold, the sending-end converter station is controlled to dynamically correct its energy reference value based on the DC link voltage, so that the sending-end converter station can absorb the surplus power generated by the AC fault. After the AC fault is detected and cleared, the sending-end converter station and the receiving-end converter station are controlled to perform sequential energy release until the isolated renewable energy system returns to normal operation, so as to realize the control of surplus power absorption of the isolated renewable energy system.

[0007] A second aspect of the present invention provides a surplus power absorption control device for an isolated renewable energy system, wherein the isolated renewable energy system is a high-voltage direct current transmission system based on a modular multilevel converter, comprising a sending-end converter station and a receiving-end converter station, and the device includes: The real-time data monitoring module is used to monitor the output energy and DC link voltage of the sending-end converter station in real time. The active absorption control module is used to control the receiving-end converter station to optimize the allocation of receiving-end current and dynamically adjust its DC voltage reference value based on the output energy when an AC fault is detected in the isolated renewable energy system, so that the receiving-end converter station can increase the output energy and the DC link voltage according to the obtained allocation and adjustment results. An auxiliary absorption control module is used to control the sending-end converter station to dynamically correct its energy reference value based on the DC link voltage when the output energy reaches a preset energy threshold and the DC link voltage reaches a preset voltage threshold, so that the sending-end converter station can absorb the surplus power generated by the AC fault. The energy release module is used to control the sending-end converter station and the receiving-end converter station to perform sequential energy release after the AC fault is detected to be cleared, until the isolated renewable energy system returns to normal operation, so as to realize the control of surplus power absorption of the isolated renewable energy system.

[0008] A third aspect of the present invention provides an electronic device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the surplus power consumption control method of the isolated renewable energy system as described above.

[0009] A fourth aspect of the present invention provides a computer-readable storage medium comprising a stored computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements the surplus power consumption control method for the isolated renewable energy system as described above.

[0010] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows: By controlling the receiving-end converter station to optimize current distribution and dynamically correct voltage reference values, the surplus power generated by AC faults is converted into active power transmission to the AC fault side and energy storage in its own capacitors, thus enabling the receiving-end converter station to preferentially absorb surplus power. When the energy of the receiving-end converter station reaches a threshold, the sending-end converter station is controlled to correct its energy reference value, allowing it to absorb surplus power through energy buffering on the renewable energy side. By controlling the sending and receiving-end converter stations to perform coordinated inertial response, the surplus power is fully absorbed, and the drastic fluctuations in DC voltage and the overvoltage risk of submodules are effectively suppressed, ensuring the safe and stable operation of the system. At the same time, the surplus energy during the fault is temporarily stored in the sending and receiving-end converter stations and released sequentially after the fault, avoiding energy waste. Without using energy-consuming devices, the utilization capacity of surplus power is improved, and the system cost and operation and maintenance costs are reduced. Attached Figure Description

[0011] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a structural diagram of an islanded renewable energy system provided in a certain embodiment of the present invention; Figure 2 This is a flowchart of a surplus power absorption control method for an isolated renewable energy system provided in a certain embodiment of the present invention; Figure 3 This is a structural diagram of a Thevenin circuit provided in a certain embodiment of the present invention; Figure 4 This is a schematic diagram of the energy control principle of a sending-end converter station provided in a certain embodiment of the present invention; Figure 5 This is a schematic diagram of the energy control principle of a receiving-end converter station provided in a certain embodiment of the present invention; Figure 6 This is an energy control timing diagram provided in a certain embodiment of the present invention when small capacity or short-term surplus power is applied; Figure 7This is an energy control timing diagram provided in a certain embodiment of the present invention when a large capacity or long-term surplus power is applied; Figure 8 This is a simulation diagram of surplus power absorption under a three-phase grounding fault via a 0.05H inductor at the receiving end, provided by a certain embodiment of the present invention. Figure 9 This is a simulation diagram of surplus power absorption under a three-phase grounding fault via a 0.02H inductor at the receiving end, provided by a certain embodiment of the present invention. Figure 10 This is a structural diagram of a surplus power absorption control device for an isolated renewable energy system according to a certain embodiment of the present invention; Figure 11 This is a structural diagram of an electronic device provided in a certain embodiment of the present invention; Figure label: Among them, 10 is the real-time data monitoring module; 20 is the active absorption control module; 30 is the auxiliary absorption control module; 40 is the energy release module; 5000 is the electronic equipment; 5001 is the processor; 5002 is the bus; 5003 is the memory; and 5004 is the transceiver. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0014] In this invention description, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In this invention description, unless otherwise stated, "a plurality of" means two or more. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0015] In the description of this invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is merely for describing specific embodiments and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0016] In one embodiment, the first aspect of the present invention provides a method for controlling surplus power absorption in an islanded renewable energy system, wherein the structure of the islanded renewable energy system is as follows: Figure 1 As shown, this is a high-voltage direct current transmission system (i.e., MMC-HVDC system) based on modular multilevel converters, including a sending-end converter station (MMC1) and a receiving-end converter station (MMC2). The wind farm / photovoltaic and other new energy units are connected to the sending-end converter station via 33kV / 230kV transformers and 230kV / 370kV transformers. The sending-end converter station is connected via a DC line (where the rated voltage U... dcn The DC side of the sending-end converter station is connected to the receiving-end converter station (640kV). The AC side of the receiving-end converter station is connected to the traditional AC grid through a 370kV / 230kV transformer, forming a connection architecture of "new energy side - DC grid - AC grid". Both the sending-end and receiving-end converter stations adopt a modular multilevel structure (containing multiple sub-modules, each with a built-in capacitor) to realize the energy conversion between the DC side and the AC side. At the same time, based on the traditional voltage source converter dual closed-loop vector control (VSC), the converter station of this invention introduces an energy control outer loop for the bridge arm voltage equation, whereby the bridge arm voltage equation is as follows: (1) In the formula, , These are the voltages of the upper and lower bridge arms of the converter, respectively. This is the DC link voltage; To adjust the system; Angular frequency; t For time; The initial phase of the AC voltage; This is the circulating voltage component, i.e., the common-mode voltage.

[0017] For the receiving-end converter station, its inner control loop has d / q-axis current regulators and pulse width modulation (PWM) modules for real-time tracking of current commands and output of modulated voltage. Its outer control loop has a constant DC voltage controller to maintain DC voltage stability and AC side voltage / frequency stability under normal operating conditions. Its energy control outer loop is used for optimized current allocation and dynamic adjustment of the DC voltage reference value under fault conditions to absorb surplus power and avoid equipment overstress. Under normal operating conditions, the receiving-end converter's outer control loop uses constant DC voltage control, generating a DC current reference value through a PI regulator to ensure the DC voltage remains stable at its rated value. The inner control loop tracks the DC current reference value, allocating d-axis (active) and q-axis (reactive) currents to maintain AC side voltage stability. Simultaneously, it collects its actual output energy E2 in real time (calculated from the submodule capacitor voltage, E∝∑U). C 2 Compared with the rated energy E0, it is in "standby monitoring" state.

[0018] For the sending-end converter station, the structure and function of its control inner loop are the same as those of the receiving-end converter station; its control outer loop has a constant AC voltage controller, which is used to maintain the stability of the AC voltage of the new energy grid connection and the transmission power under normal operating conditions; its energy control outer loop is used to correct its own energy reference value and judge the degree of fault under fault conditions, thereby assisting in absorbing surplus power and adaptively releasing energy. Under normal operating conditions, the control outer loop of the sending-end converter station adopts constant AC voltage control—a PI regulator generates a q-axis current reference value to maintain the stability of the AC voltage on the renewable energy grid-connected side, and simultaneously generates a d-axis current reference value to match the renewable energy output, smoothly transmitting power to the receiving end; it also monitors two key signals in real time: the DC link voltage of the receiving-end converter station (reflecting the power balance of the DC line; if the receiving end's absorption is obstructed, this value will actually rise to the preset voltage threshold); and the output energy of the receiving-end converter station (obtained through the communication link; if it is not less than the preset energy threshold, it indicates that the receiving end's energy storage is saturated); the energy of its own submodule capacitor is maintained at the rated value E0 (per unit value 1.0), in a "low-load energy storage state," reserving surplus power storage space.

[0019] In one embodiment, the present invention proposes a method for controlling the surplus power absorption of an isolated renewable energy system, such as... Figure 2 As shown, it is applied to a control terminal that is communicatively connected to both the sending-end and receiving-end converter stations (it can be a centralized controller or multiple controllers deployed in a distributed manner but logically unified and coordinated) to achieve control over... Figure 1 The method for absorbing surplus power in the system shown includes: S1. Real-time monitoring of the output energy and DC link voltage of the sending-end converter station. Specifically, this invention continuously monitors the system's operating data through various sensors, such as DC link voltage (voltage on the DC line), output energy of each converter station, AC side voltage and current, etc.; wherein, the maximum energy threshold of the sending-end and receiving-end converter stations... As shown in the following formula: (2) In the formula, U Cmax and U C0 The maximum allowable voltage and rated voltage of the submodule capacitor; E 0 represents the rated energy of the converter station.

[0020] Similarly, the real-time output energy of the sending and receiving end converter stations can be calculated by replacing the maximum allowable voltage of the submodule capacitor in equation (2) with the real-time voltage of the submodule capacitor; of course, it can also be calculated by directly collecting the real-time operating data of the converter station using multiple sensors.

[0021] S2. When an AC fault is detected in the isolated renewable energy system, the receiving-end converter station is controlled to optimize the allocation of the receiving-end current and dynamically adjust its DC voltage reference value based on the output energy, so that the receiving-end converter station increases the output energy and the DC link voltage according to the obtained allocation and adjustment results. Specifically, when it is detected that the isolated renewable energy system has surplus power due to an AC side fault (such as a sudden drop in AC side voltage) and causes the DC link voltage to start rising, it is determined that a surplus power AC fault has occurred, and the subsequent coordination control logic for the receiving-end converter station is triggered.

[0022] In one embodiment, step S2 includes: The output current of the receiving-end converter station is controlled to be increased to the maximum value, and the receiving-end converter station is controlled to construct a mathematical model of its output active power and d-axis current and q-axis current based on its own topology. The receiving-end converter station is controlled to construct constraints based on the relationship between the output current and the d-axis current and the q-axis current, and to construct a target model based on the mathematical model using the Lagrange multiplier method. The receiving-end converter station is controlled to solve the target model, obtain the optimal weights of the d-axis current and the q-axis current, and execute the solution so that the receiving-end converter station actively absorbs the surplus power, thereby increasing the output energy.

[0023] Specifically, when a fault is detected on the AC side (such as a three-phase short circuit), causing power output to be blocked and resulting in a surge of surplus power to the receiving-end converter station, that is, when the voltage sensor detects a voltage drop on the AC side (or a power imbalance signal), a command signal is generated to control the receiving-end converter station to immediately switch from "normal control mode" to "fault surplus absorption mode". The receiving-end converter station is then controlled to actively absorb surplus power through a dual mechanism of current optimization distribution and output energy enhancement. In other words, the command signal is used to control the receiving-end converter station to perform the following operations: First, adjust the reference value of the inner loop current to increase its output current to the maximum value. (Typically 1.5 pu). To simplify the control logic, this invention equates the AC system from the receiving-end converter station outlet to the receiving-end circuit to a Thevenin circuit, the structure of which is as follows: Figure 3 As shown, where, This is the equivalent open-circuit voltage of the receiving-end system; The system equivalent impedance (including transformer impedance) Z T System impedance Zsys Short-circuit grounding impedance Z f The receiving-end converter station outlet is considered a "PQ node" (active / reactive controllable node), and its outlet voltage is u. d The surplus power is absorbed by controlling the active power P2 and reactive power Q2 output from this node. Therefore, based on its own topology—the Thevenin circuit—a mathematical model is constructed for its output active power, output reactive power, and d-axis and q-axis currents, thereby clarifying the relationship between P2 and i. d (Active current), i q The variation law of (reactive current); whereby the mathematical model is expressed by the following formula: (3) 4 (5) In the formula, This is the equivalent open-circuit voltage of the receiving-end system; This is the phase difference between the equivalent open-circuit voltage and the equivalent circuit port voltage. X eq This is the system's equivalent impedance.

[0024] Subsequently, constraints are constructed based on the relationship between the output current and the d-axis and q-axis currents, as shown in the following equation: 6 With the goal of maximizing P2, an objective function L is constructed using the Lagrange multiplier method combined with a mathematical model; the objective function is expressed by the following equation: 7 In the formula, It is a Lagrange multiplier.

[0025] Taking the partial derivatives of the three variables in equation (7) and setting the partial derivatives to 0, we can obtain: (8) Solving equation (8) and discarding the negative roots, the solution that maximizes the active power P2 is the solution for the corresponding operating condition i. d i q The optimal weight is determined, and the control inner loop of the receiving-end converter station replaces the reference value under normal operating conditions to output current according to the optimal weight, so that the receiving-end converter station actively absorbs surplus power, that is, converts surplus power into active power transmission to the AC fault side and energy storage of the converter station submodule capacitors, thereby increasing the output energy of the receiving-end converter station; where the output energy is essentially the energy stored in the submodule capacitors of the receiving-end converter station.

[0026] This invention controls the receiving-end converter station to construct a mathematical model based on the converter station's own topology. The method is universal and applicable to various converter station types, facilitating practical engineering applications. The receiving-end converter station is controlled to solve for the optimal solution using the Lagrange multiplier method, balancing active and reactive power demands while satisfying current constraints, ensuring the converter station operates at its optimal operating point and extending equipment lifespan. Furthermore, under the premise that the output current reaches its hardware limits, the receiving-end converter station prioritizes active power output by optimizing the weights of the d-axis and q-axis currents, effectively absorbing surplus power in the system, avoiding wind and solar power curtailment, and improving energy utilization efficiency.

[0027] In one embodiment, step S2 further includes: When the output energy is detected to reach the energy warning threshold, the receiving-end converter station is controlled to dynamically correct its DC voltage reference value based on the output energy using a nonlinear function to obtain the voltage reference correction value. The receiving-end converter station is controlled to generate and execute a corresponding current control command based on the voltage reference correction value, so as to raise the DC link voltage.

[0028] Specifically, when the surplus power is too large and current optimization alone cannot fully absorb it, this invention raises the DC voltage reference value of the receiving-end converter station to temporarily store the surplus power using the energy storage characteristics of its submodule capacitors. This invention generates command signals to control the receiving-end converter station to execute the following steps: Real-time output energy after lifting was monitored. Reaching the energy warning threshold (Pre-set to avoid) Exceeding the preset energy threshold When the voltage reference value is triggered (it can also be used as the energy control trigger value of the new energy sending station pole), it triggers the correction of the voltage reference value. That is, based on its output energy, it uses a nonlinear function to dynamically correct its own DC voltage reference value to obtain the voltage reference correction value. This correction process is expressed by the following formula: (9) In the formula, U dcref The DC voltage reference value is used as the reference value, and the corrected value is called the voltage reference correction value. U dcmax This is the maximum permissible voltage on the DC link of the DC system. U dcn This is the rated value of the DC link voltage.

[0029] Based on the calculated voltage reference correction value, a corresponding current control command is generated and executed to raise the DC link voltage: Outer loop voltage control: The new voltage reference correction value is compared with the currently measured DC link voltage, and the deviation is passed through a PI (proportional-integral) controller to generate a corresponding d-axis current reference value (in the dq rotating coordinate system, the d-axis current mainly controls active power, i.e., controls DC voltage); Inner loop current control: Based on the d-axis current reference value and the q-axis current reference value in the optimal weight, a modulation wave signal is generated by the inner loop current controller (such as a proportional resonant PR controller or a feedforward decoupled PID) to drive the converter switching devices (such as IGBTs) to execute; so that the receiving-end converter station increases the active current absorbed from the AC grid to raise its DC side voltage, making it track the new, higher reference value, and then converting the surplus power on the AC side into electric field energy stored in the DC capacitor, thereby achieving the purpose of "raising the DC link voltage" and "actively absorbing surplus power".

[0030] At the receiving-end converter station, this invention abandons the traditional fixed DC voltage control or simple linear correction strategy. Instead, it controls the receiving-end converter station to construct a DC voltage reference correction function that is nonlinearly related to its output energy state. This function maintains a smooth change before the energy reaches a warning value, and rapidly raises the voltage reference value when approaching the upper limit of energy. This fully utilizes the energy storage capacity of the capacitor, provides a smooth transition for control, effectively prevents overcharging, and thus safely stores the absorbed energy. By controlling the sending and receiving-end converter stations to perform a coordinated inertial response, the surplus power is fully absorbed, and the drastic fluctuations in DC voltage and the overvoltage risk of submodules are effectively suppressed, ensuring the safe and stable operation of the system.

[0031] S3. When the output energy reaches a preset energy threshold and the DC link voltage reaches a preset voltage threshold, the sending-end converter station is controlled to dynamically correct its energy reference value based on the DC link voltage, so that the sending-end converter station can absorb the surplus power generated by the AC fault. Specifically, if the output energy of the receiving-end converter station reaches the preset energy threshold and its DC link voltage reaches the preset voltage threshold, both of these conditions are met, it means that the receiving-end capacitor is close to saturation and cannot continue to store energy. The DC power accumulates, and the receiving end cannot fully transmit the power, which is the limit of receiving-end absorption. This triggers the sending-end converter station to switch from "standby" to "supplementary absorption mode" so that it can assist in absorbing the surplus power by correcting the energy reference value and storing energy in the sub-module. Similarly, if either of the above two conditions is not met, it means that the receiving-end converter station is capable of absorbing the surplus power generated by this AC fault. Therefore, the sending-end converter station does not need to assist in absorption and is controlled to remain in standby mode and maintain normal control logic. Its output energy E1 remains at E0, and no current or voltage command is adjusted.

[0032] In one embodiment, controlling the sending-end converter station to dynamically correct its energy reference value based on the DC link voltage, so that the sending-end converter station can absorb the surplus power generated by the AC fault, includes: The sending-end converter station corrects its own energy reference value based on the overshoot of the DC link voltage to obtain the energy reference correction value; The sending-end converter station is controlled to generate and execute a corresponding inner loop current command based on the energy reference correction value, so that the sending-end converter station can directly absorb the surplus power from the new energy side.

[0033] Specifically, after the sending-end converter station is triggered, the control terminal generates a command signal to control the sending-end converter station to perform the following steps: The energy reference value is corrected based on the overshoot of the DC link voltage (i.e., the difference between the preset upper voltage threshold of 1.08 pu and the preset lower voltage threshold of 1.02 pu) and its duration (the time it takes for the DC voltage to rise from 1.02 pu to 1.08 pu), resulting in the energy reference correction value. This process is represented by the following formula: 10 In the formula, U dcref This is the voltage reference value for the DC link voltage; ∆ U dcn For overshoot; ∆ t n Its duration; For the output energy E2 of the receiving-end converter station to reach the preset energy threshold E alert The moment; t2 represents the fault clearing time.

[0034] Subsequently, based on the calculated energy reference correction value, a corresponding inner loop current command is generated and controlled to execute the inner loop control, so that the sending-end converter station can directly absorb surplus power from the new energy side. That is, the energy control outer loop converts the energy reference correction value into the d-axis current reference value through the PI controller and executes it (reducing the d-axis current and reducing the amount of new energy power transmitted to the DC side). At the same time, the surplus power is temporarily stored in the form of "capacitor energy storage" by increasing the voltage of the submodule capacitor.

[0035] This invention controls the sending-end converter station to correct its energy reference value by utilizing the overshoot of the DC link voltage. The nonlinear relationship employed makes the control process very smooth, avoiding secondary impacts on power and voltage. By controlling the sending-end converter station itself, it can directly absorb excess power from the connected renewable energy side, avoiding the waste of renewable energy and improving energy utilization efficiency.

[0036] S4. After the AC fault is detected to be cleared, the sending-end converter station and the receiving-end converter station are controlled to perform sequential energy release until the isolated renewable energy system returns to normal operation, so as to realize the surplus power absorption control of the isolated renewable energy system; after the AC fault is detected to be cleared (such as the AC voltage returning to normal value), a command signal is generated to control the sending-end converter station and the receiving-end converter station to perform sequential energy release (i.e., the receiving end releases first, the sending end releases later, and the release rate of the sending end is adaptively adjusted according to the AC voltage drop depth) until the isolated renewable energy system returns to normal operation, so as to realize the surplus power absorption control of the isolated renewable energy system.

[0037] In one embodiment, controlling the sending-end converter station and the receiving-end converter station to perform sequential energy release includes: The receiving-end converter station is controlled to release energy at a first fixed release rate after the AC fault is cleared, so as to reduce the DC link voltage; wherein, the first fixed release rate is determined based on the difference between the maximum operating capacity of the receiving-end converter station and the actual transmission power. When the DC link voltage is detected to have recovered to its rated value, the sending-end converter station is controlled to release energy at a second preset rate determined based on the degree of fault.

[0038] Specifically, after determining that the fault has been cleared, the control unit switches the receiving-end converter station from "absorption mode" to "release mode" so that it releases energy at a first fixed release rate, feeding back the temporarily stored surplus power to the system. 2ref From E alert The voltage drops to E0, and at the same time, it falls back: U dcref Synchronous callback, U dc From U dcmaxGradually reduced to U dcn This is to reduce the DC link voltage; wherein, the first fixed release rate is determined based on the difference between the maximum operating capacity of the receiving-end converter station and its actual transmission power, and its calculation process is expressed by the following formula: 11 In the formula, The first fixed release rate; P 2max and P 2 represents the maximum allowable operating capacity and actual transmission power of the receiving-end converter station, respectively. P 2max It is generally 1.2 times. P 2.

[0039] During the energy release period at the sending-end converter station (i.e., when the DC link voltage drops but does not reach the rated value), the control maintains the energy reference value at the maximum value during the replenishment phase, allowing it to enter an energy holding phase and not participate in energy release. The control inner loop maintains the current current command to avoid superimposing with the energy release at the receiving-end converter station, which could lead to U... dc A sudden drop; the energy reference value of the sending-end converter station during this process is shown in the following formula: 12 In the formula, t 3 represents the moment when the DC link voltage returns to its rated value.

[0040] Simultaneously, the sending-end converter station monitors the DC link voltage of the receiving-end converter station in real time during the energy release period, and triggers the sending-end converter station to release energy based on the severity of the fault when the voltage returns to its rated value.

[0041] In one embodiment, controlling the sending-end converter station to release energy at a second preset rate determined based on the fault level includes: The sending-end converter station is controlled to collect AC voltage drop data of the isolated renewable energy system during a fault, and the fault severity is determined based on the AC voltage drop data. The sending-end converter station is controlled to determine the second preset rate based on its actual transmission power and the degree of fault, and the sending-end converter station is controlled to release energy at the second preset rate.

[0042] Specifically, the control unit collects the instantaneous AC voltage (u) of the faulty phase on the AC side during an AC fault at the sending-end converter station. a u b u c The voltage dip data is used as AC voltage sag data, and the effective value of the fault phase voltage is calculated using a fast voltage calculation method (avoiding the delay of direct measurement). This process is expressed by the following formula: 13 In the formula, U fa , U fb , U fc This represents the effective value of the amplitude of the fault phase voltage.

[0043] Subsequently, the sending-end converter station is controlled to sort the calculated effective values ​​of the fault phase voltage amplitude from smallest to largest, select the smallest effective value to characterize the severity of the AC fault, and combine it with its actual transmission power to calculate the second preset rate. The sending-end converter station is then controlled to release energy at the second preset rate. The calculation process of the second preset rate is expressed by the following formula: 14 In the formula, The second preset rate; U RMS This is the effective value of the rated AC phase voltage; P 1max and P 1 represents the maximum allowable operating capacity and actual transmission power of the sending-end converter station, respectively. P 1max It is generally 1.2 times. P 1.

[0044] This invention controls the receiving end to act first, with the sending end following behind, forming a clear recovery sequence and avoiding power oscillations and conflicts. The recovery rate of the sending-end converter station is adaptively determined based on the severity of the grid fault. In the case of a minor fault, energy is released quickly to accelerate the system recovery speed, while in the case of a severe fault, the energy release rate is slowed down to avoid overcharging of capacitors and overstressing of equipment, further improving the absorption and stability capabilities of the MMC-HVDC system. By allowing the sending-end and receiving-end converter stations to release the excess energy accumulated during the fault in a step-by-step and coordinated manner, the smoothness and safety of the system's recovery from the fault state to rated operation are ensured.

[0045] In one embodiment, the energy control principle of the sending-end converter station is as follows: Figure 4 As shown, the energy control principle of the sending-end converter station is as follows: Figure 5 As shown. The isolated renewable energy sending-end dual-loop control uses constant AC voltage control to maintain a stable AC grid-connected voltage. The outer loop of energy control collects the actual MMC energy signal, which, after passing through a PI circuit, generates a reference value signal i for DC current control. dcref The active receiver-end dual-loop control is responsible for maintaining the energy stability of the MMC station electrode. The constant DC voltage control generates a reference value signal i for DC current control via a PI circuit. dcref It is responsible for maintaining the stable operation of the system's DC voltage, where N is the number of submodules in a single bridge arm; the DC current reference value i is obtained through the outer loop control.dcref After comparing with the actual value, the DC modulation ratio M required for control is finally generated. dc The basic equation for this stage is shown below: 12 In the formula, k p k i These are the proportional and integral coefficients of the PI control loop.

[0046] The obtained M dc The voltage is fed into the bridge arm voltage calculation module and compared with the three-phase modulation ratio m obtained from the dual-loop control. j (j=a,b,c) and the circulating current suppression modulation ratio m 2j The modulation voltage u of the upper and lower bridge arms was obtained after calculation. pj u nj Finally, the modulation voltage is approximated by the nearest level and sorted by voltage equalization to obtain the trigger pulse required for control; the calculation process of the modulation voltage of the upper and lower bridge arms is shown in the following formula: ⒃ Energy control timing when small capacity or short-term surplus power is applied, such as Figure 6 As shown, t < t At time 1, the MMC-HVDC system is in rated operating condition, and the energy command of each station is 1 (the following text and simulation use per-unit values). t = t An error occurred at time 1. After detecting the error, MMC2 began adjusting the energy control reference value. E 2ref Tracking actual values E 2. Simultaneously increase the output current to i max The d-axis and q-axis current weights are assigned based on the solution results of equation (8). During this period, the DC voltage control outer loop is based on... E 2. Real-time rise DC voltage reference value U dcref As shown in equation (9), where E alert The energy value is set at 1.96 times the rated capacitor voltage, i.e. E alert =1.96 pu; t = t Fault clearance at time 2, at which point the MMC2 energy value has not reached E alert The threshold, the whole t 1< t < t During period 2, MMC1 does not need to participate in earnings absorption; t = tAt time 2, MMC2 enters the energy release phase and regulates... E 2ref Start with a fixed slope k release2 It dropped to 1.0 throughout the process. U dcref It still satisfies equation (9). k release2 Take the maximum value, which is ( P 2max - P 2). t = t At time 3, the system energy was completely released and the system returned to a stable operating state.

[0047] Energy control timing when large capacity or long-term surplus power is applied, such as Figure 7 As shown, t < t At time 1, the MMC-HVDC system is in rated operating condition, and the energy command of each station is 1; t = t An error occurred at time 1. After detecting the error, MMC2 began adjusting the energy control reference value. E 2ref Tracking actual values E 2. Simultaneously increase the output current to i max The d-axis and q-axis current weights are assigned based on the solution results of equation (8). During this period, the DC voltage control outer loop is based on... E 2. Real-time rise DC voltage reference value U dcref , as in equation (9); t = t 1-1 At that time, the MMC2 energy was detected to have reached the warning value. E alert At the same time, the DC voltage also rose to U dcmax To avoid the risk of over-energy consumption during further charging of MMC2, MMC1 began to participate in surplus absorption; t = t At time 2, the fault is cleared, and MMC2 begins to enter the energy release phase. E 2ref Start with a fixed slope k release2 It dropped to 1.0 throughout the process. U dcref If equation (9) is still satisfied, then MMC1 enters the surplus maintenance phase until it is detected. t At time 3, the DC voltage returns to its rated value. t = tAt time 3, MMC1 begins to enter the energy release phase, adjusting according to the degree of fault. E 1ref It begins to decrease to 1.0 at the rate of equation (14); t = t At time 4, the system energy was completely released and the system returned to a stable operating state.

[0048] The receiving-end energy control, through current optimization calculation and control during faults and real-time correction of the DC voltage reference value, undertakes the main task of absorbing surplus power under fault conditions, ensuring that the DC voltage remains within the allowable range. When the receiving end cannot independently absorb surplus power, the sending-end energy control dynamically changes the energy reference value to directly absorb the surplus power flowing into the DC grid from the renewable energy side. When releasing energy, the fault severity is assessed based on the AC voltage drop, and the energy release rate is adaptively adjusted. In the case of minor faults, energy is released quickly to accelerate system recovery, while in the case of severe faults, the energy release rate is slowed down to avoid capacitor overcharging and equipment overstress, further improving the absorption and stability capabilities of the MMC-HVDC system.

[0049] To verify the effectiveness of the solution described in this invention, specific embodiments of the invention are now described in detail with reference to the accompanying drawings and examples. However, this invention is not limited to the described embodiments. The steps are as follows: 1) In PSCAD / EMTDC electromagnetic simulation software, build such a system. Figure 1 The simulation model of the isolated renewable energy system is shown.

[0050] 2) Simulation tests were conducted to simulate the effect of small-capacity or short-term surplus power under a minor fault at the receiving end. A three-phase short-circuit grounding fault occurred on the AC side of station MMC2 at 7 seconds, and the fault was cleared after 200ms. The simulation results were obtained—the simulation diagram of surplus power absorption under a three-phase grounding fault at the receiving end via a 0.05H inductor is shown below. Figure 8 As shown, Figure 8 The table shows the energy fluctuations of MMC2 and MMC1, DC voltage fluctuations, active power fluctuations of MMC2, and voltage fluctuations of the submodules of MMC2 and MMC1 from top to bottom. Under this operating condition, the theoretical calculated value of the active power P2 obtained from equation (8) is 0.6711 pu, which differs from the simulation result of 0.66 pu. This difference is mainly due to the unconsidered resistance loss and control error, and the error level is within an acceptable range.

[0051] 3) Simulation tests were conducted to simulate the large-capacity or long-term surplus power effect under a severe fault at the receiving end. A three-phase short-circuit grounding fault occurred on the AC side of station MMC2 at 7 seconds, and the fault was cleared after 200ms. The simulation results were obtained—the simulation diagram of surplus power absorption under a three-phase grounding fault at the receiving end via a 0.02H inductor is shown below. Figure 9 As shown, Figure 9 The table shows the energy fluctuations of MMC2 and MMC1, DC voltage fluctuations, active power fluctuations of MMC2, and voltage fluctuations of the submodules of MMC2 and MMC1 from top to bottom. Under this operating condition, the theoretical calculated value of the active power P2 obtained from equation (8) is 0.3717 pu, which differs from the simulation result of 0.36 pu. This difference is mainly due to the unconsidered resistance loss and control error, and the error level is within an acceptable range.

[0052] Depend on Figure 8 , Figure 9 As can be seen, throughout the entire fault process, the energy control strategy proposed in this invention can effectively absorb surplus power under different fault levels. Submodule voltage fluctuations and DC voltage fluctuations can be controlled within reasonable allowable ranges, and the overvoltage risk of the system is effectively controlled. Furthermore, this scheme does not require the participation of energy-consuming devices, and the surplus energy generated during the fault process can be reintroduced into the system after the fault, significantly improving the utilization rate of surplus energy and demonstrating good economic characteristics.

[0053] This invention addresses the issue of how to absorb surplus power in isolated renewable energy systems while minimizing the use of energy-consuming devices. A surplus power absorption control method for isolated renewable energy systems is designed. This method controls the receiving-end converter station to optimize current allocation and dynamically correct voltage reference values, converting surplus power generated by AC faults into active power transmission to the AC fault side and energy storage in its own capacitor, thus enabling the receiving-end converter station to preferentially absorb surplus power. When the energy at the receiving-end converter station reaches a threshold, the sending-end converter station is controlled to correct the energy reference value. The system is designed to enable the sending-end converter station to absorb surplus power through energy buffering on the renewable energy side. By controlling the sending-receiving converter station to perform a coordinated inertial response, the surplus power is fully absorbed, and the severe fluctuations in DC voltage and the overvoltage risk of submodules are effectively suppressed, ensuring the safe and stable operation of the system. At the same time, the surplus energy during the fault is temporarily stored in the sending-receiving converter station and released sequentially after the fault, avoiding energy waste. Without using energy-consuming devices, the system improves the utilization of surplus power and reduces system construction and maintenance costs.

[0054] It should be noted that although the steps in the flowchart above are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order requirement for the execution of these steps, and they can be executed in other orders.

[0055] In another embodiment, such as Figure 10As shown, a second aspect of the present invention provides a surplus power absorption control device for an isolated renewable energy system, wherein the isolated renewable energy system is a high-voltage direct current transmission system based on a modular multilevel converter, comprising a sending-end converter station and a receiving-end converter station, and the device includes: Real-time data monitoring module 10 is used to monitor the output energy and DC link voltage of the sending-end converter station in real time; The active absorption control module 20 is used to control the receiving-end converter station to optimize the allocation of receiving-end current and dynamically adjust its DC voltage reference value based on the output energy when an AC fault is detected in the isolated renewable energy system, so that the receiving-end converter station can increase the output energy and the DC link voltage according to the obtained allocation and adjustment results. The auxiliary absorption control module 30 is used to control the sending-end converter station to dynamically correct its energy reference value based on the DC link voltage when it is detected that the output energy reaches a preset energy threshold and the DC link voltage reaches a preset voltage threshold, so that the sending-end converter station can absorb the surplus power generated by the AC fault. The energy release module 40 is used to control the sending-end converter station and the receiving-end converter station to perform sequential energy release after the AC fault is detected to be cleared, until the isolated renewable energy system returns to normal operation, so as to realize the surplus power absorption control of the isolated renewable energy system.

[0056] It should be noted that each module in the aforementioned surplus power absorption control device for an isolated renewable energy system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module. For specific limitations regarding the surplus power absorption control device for an isolated renewable energy system, please refer to the limitations of the surplus power absorption control method for an isolated renewable energy system described above; both have the same function and role, and will not be repeated here.

[0057] A third aspect of the present invention provides an electronic device comprising: Processor, memory, and bus; The bus is used to connect the processor and the memory; The memory is used to store operation instructions; The processor is configured to execute the operation instructions by calling the operation instructions, thereby causing the processor to perform the operation corresponding to the surplus power consumption control method of an islanded new energy system as shown in the first aspect of the present invention.

[0058] In one alternative embodiment, an electronic device is provided, such as Figure 11As shown, Figure 11 The illustrated electronic device 5000 includes a processor 5001 and a memory 5003. The processor 5001 and the memory 5003 are connected, for example, via a bus 5002. Optionally, the electronic device 5000 may also include a transceiver 5004. It should be noted that in practical applications, the transceiver 5004 is not limited to one type, and the structure of this electronic device 5000 does not constitute a limitation on the embodiments of the present invention.

[0059] Processor 5001 may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in connection with this disclosure. Processor 5001 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0060] Bus 5002 may include a path for transmitting information between the aforementioned components. Bus 5002 may be a PCI bus or an EISA bus, etc. Bus 5002 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 11 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0061] The memory 5003 may be a ROM or other type of static storage device capable of storing static information and instructions, RAM or other type of dynamic storage device capable of storing information and instructions, or it may be an EEPROM, CD-ROM or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto.

[0062] The memory 5003 is used to store application code that executes the present invention, and its execution is controlled by the processor 5001. The processor 5001 is used to execute the application code stored in the memory 5003 to implement the content shown in any of the foregoing method embodiments.

[0063] Among them, electronic devices include, but are not limited to: mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), and in-vehicle terminals (such as in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers.

[0064] The fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the surplus power consumption control method of an islanded renewable energy system as shown in the first aspect of the present invention.

[0065] Another embodiment of the present invention provides a computer-readable storage medium storing a computer program that, when run on a computer, enables the computer to execute the corresponding content in the foregoing method embodiments.

[0066] Furthermore, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0067] In summary, this invention relates to the field of high-voltage direct current (HVDC) transmission technology, and discloses a method and apparatus for controlling the absorption of surplus power in an isolated renewable energy system. By monitoring the output energy and DC link voltage of the sending-end converter station, and when an AC fault exists in the isolated renewable energy system, the receiving-end converter station is controlled to optimize the current allocation at the receiving end and dynamically adjust the DC voltage reference value to prioritize the absorption of surplus power, thereby increasing the output energy and DC link voltage. When the output energy reaches the energy demand and the DC link voltage reaches the voltage demand, the sending-end converter station is controlled to correct the energy reference value so that the sending-end converter station can absorb surplus power through renewable energy. After the AC fault is cleared, the sending-end and receiving-end converter stations are controlled to perform sequential energy release until the system returns to normal operation. This method achieves the absorption control of surplus power in the system through coordinated inertial response and sequential energy release without using energy-consuming devices.

[0068] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0069] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A method for controlling surplus power absorption in an isolated renewable energy system, characterized in that, The isolated renewable energy system is a high-voltage direct current transmission system based on modular multilevel converters, comprising a sending-end converter station and a receiving-end converter station. The method includes: Real-time monitoring of the output energy and DC link voltage of the sending-end converter station; When an AC fault is detected in the isolated renewable energy system, the receiving-end converter station is controlled to optimize the allocation of the receiving-end current and dynamically adjust its DC voltage reference value based on the output energy, so that the receiving-end converter station increases the output energy and the DC link voltage according to the obtained allocation and adjustment results. When the output energy reaches a preset energy threshold and the DC link voltage reaches a preset voltage threshold, the sending-end converter station is controlled to dynamically correct its energy reference value based on the DC link voltage, so that the sending-end converter station can absorb the surplus power generated by the AC fault. After the AC fault is detected and cleared, the sending-end converter station and the receiving-end converter station are controlled to perform sequential energy release until the isolated renewable energy system returns to normal operation, so as to realize the control of surplus power absorption of the isolated renewable energy system.

2. The surplus power absorption control method for an isolated renewable energy system according to claim 1, characterized in that, The control of the receiving-end converter station to optimize the allocation of receiving-end current and dynamically adjust its DC voltage reference value based on the output energy, so that the receiving-end converter station increases the output energy and the DC link voltage according to the obtained allocation and adjustment results, includes: The output current of the receiving-end converter station is controlled to be increased to the maximum value, and the receiving-end converter station is controlled to construct a mathematical model of its output active power and d-axis current and q-axis current based on its own topology. The receiving-end converter station is controlled to construct constraints based on the relationship between the output current and the d-axis current and the q-axis current, and to construct a target model based on the mathematical model using the Lagrange multiplier method. The receiving-end converter station is controlled to solve the target model, obtain the optimal weights of the d-axis current and the q-axis current, and execute the solution so that the receiving-end converter station actively absorbs the surplus power, thereby increasing the output energy.

3. The surplus power absorption control method for an isolated renewable energy system according to claim 2, characterized in that, The method of controlling the receiving-end converter station to optimize the allocation of receiving-end current and dynamically adjust its DC voltage reference value based on the output energy, so that the receiving-end converter station increases the output energy and the DC link voltage according to the obtained allocation and adjustment results, further includes: When the output energy is detected to reach the energy warning threshold, the receiving-end converter station is controlled to dynamically correct its DC voltage reference value based on the output energy using a nonlinear function to obtain the voltage reference correction value. The receiving-end converter station is controlled to generate and execute a corresponding current control command based on the voltage reference correction value, so as to raise the DC link voltage.

4. The surplus power absorption control method for an isolated renewable energy system according to claim 1, characterized in that, The control of the sending-end converter station to dynamically correct its energy reference value based on the DC link voltage, so as to enable the sending-end converter station to absorb the surplus power generated by the AC fault, includes: The sending-end converter station corrects its own energy reference value based on the overshoot of the DC link voltage to obtain the energy reference correction value; The sending-end converter station is controlled to generate and execute a corresponding inner loop current command based on the energy reference correction value, so that the sending-end converter station can directly absorb the surplus power from the new energy side.

5. The surplus power absorption control method for an isolated renewable energy system according to claim 1, characterized in that, The control of sequential energy release by the sending-end converter station and the receiving-end converter station includes: After the AC fault is cleared, the receiving-end converter station releases energy at a first fixed release rate to reduce the DC link voltage. When the DC link voltage is detected to have recovered to its rated value, the sending-end converter station is controlled to release energy at a second preset rate determined based on the degree of fault.

6. The surplus power absorption control method for an isolated renewable energy system according to claim 5, characterized in that, The first fixed release rate is determined based on the difference between the maximum operating capacity of the receiving-end converter station and the actual transmission power.

7. The surplus power absorption control method for an isolated renewable energy system according to claim 5, characterized in that, The control of the sending-end converter station to release energy at a second preset rate determined based on the fault level includes: The sending-end converter station is controlled to collect AC voltage drop data of the isolated renewable energy system during a fault, and the fault severity is determined based on the AC voltage drop data. The sending-end converter station is controlled to determine the second preset rate based on its actual transmission power and the degree of fault, and the sending-end converter station is controlled to release energy at the second preset rate.

8. A surplus power absorption control device for an isolated renewable energy system, characterized in that, The isolated renewable energy system is a high-voltage direct current transmission system based on modular multilevel converters, comprising a sending-end converter station and a receiving-end converter station. The device includes: The real-time data monitoring module is used to monitor the output energy and DC link voltage of the sending-end converter station in real time. The active absorption control module is used to control the receiving-end converter station to optimize the allocation of receiving-end current and dynamically adjust its DC voltage reference value based on the output energy when an AC fault is detected in the isolated renewable energy system, so that the receiving-end converter station can increase the output energy and the DC link voltage according to the obtained allocation and adjustment results. An auxiliary absorption control module is used to control the sending-end converter station to dynamically correct its energy reference value based on the DC link voltage when the output energy reaches a preset energy threshold and the DC link voltage reaches a preset voltage threshold, so that the sending-end converter station can absorb the surplus power generated by the AC fault. The energy release module is used to control the sending-end converter station and the receiving-end converter station to perform sequential energy release after the AC fault is detected to be cleared, until the isolated renewable energy system returns to normal operation, so as to realize the control of surplus power absorption of the isolated renewable energy system.

9. An electronic device, characterized in that, The system includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the surplus power consumption control method for an islanded renewable energy system as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements the surplus power consumption control method for an islanded renewable energy system as described in any one of claims 1 to 7.

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