VSC-HVDC adaptive fault ride-through control method, system and device considering near-field new energy influence

Abstract

The invention relates to the technical field of power systems and flexible direct current power transmission, in particular to a VSC-HVDC self-adaptive fault ride-through control method, system and device considering the influence of near-field new energy. The method comprises the following steps: firstly, according to real-time fault equivalent parameters, solving the maximum fault allowable time of a receiving-end converter station considering the influence of the near-region new energy, and taking the maximum fault allowable time as an important basis for the severity of the fault and the subsequent formulation of a control strategy; according to different possible fault durations, a control strategy is flexibly adjusted, whether unloading needs to be started or control parameters need to be adjusted is determined, the fault ride-through capacity of the system is improved, reasonable cooperation of unloading is achieved, it is ensured that dependence on unloading input is reduced, and system energy loss is reduced, so that the efficiency and adaptability of fault ride-through are improved, and the fault ride-through reliability is improved. And a powerful technical guarantee is provided for stable operation of the flexible direct-current power transmission system in a new energy access scene.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power systems and flexible HVDC technology, and particularly relates to a VSC-HVDC adaptive fault ride-through control method, system and equipment considering the influence of new energy in the near area. BACKGROUND

[0002] With the rapid development of flexible HVDC technology, it has become an important technical means for connecting large-scale new energy and regional power grids due to its advantages in long-distance, large-capacity and high controllability. Flexible HVDC system can effectively solve the problem of power loss in the transmission process of traditional AC power grid and realize flexible regulation of power grid, especially suitable for connecting renewable energy with large fluctuations. However, when a short-circuit fault occurs in the AC power grid, the voltage of the power grid drops sharply, resulting in a decrease in the output power of the receiving end converter station, thereby causing the DC voltage to rise and form an unbalanced power. If the DC voltage is not effectively controlled at this time, it may exceed the safety voltage limit, damage power electronic devices, and even cause the system to fail to recover in time. In order to ensure the stable operation of the system during the fault period, the flexible HVDC system must have the ability to absorb unbalanced power during the power grid fault, thereby realizing fault ride-through.

[0003] At present, the fault ride-through method of flexible HVDC system includes DC voltage control and unloading control. The DC voltage control adjusts the power output of the receiving end converter station to control the rise of the DC voltage, ensuring that the power electronic devices will not be damaged due to overvoltage. While the unloading control consumes unbalanced energy to slow down the rising speed of the DC voltage. There are two types of unloading, centralized and distributed. Centralized unloading connects energy-consuming resistors through external modules, which has fast response speed, but may cause electrical shock and thermal stress. Distributed unloading adjusts power through resistors in sub-modules, which can smoothly adjust the unloading power, but will face a large heat dissipation burden, affecting the energy efficiency of the system. In addition, some studies adjust the topology structure or power distribution method of the sending end converter station to improve the fault ride-through capability. By changing the capacity of the sending end converter station or adjusting its output power, the fault handling capability of the system can be improved to a certain extent, but these methods are not ideal when faults occur frequently.

[0004] Although the existing fault ride-through method can suppress the rise of DC voltage to a certain extent and guarantee the safe operation of the system, the influence of the controlled characteristics of the nearby new energy on the fault ride-through of the flexible DC power transmission system is ignored. When the power grid fails, the output current of the new energy under low penetration is controlled by the grid voltage. When the flexible DC power transmission system changes the grid voltage during fault ride-through, the change of the output current of the new energy will directly affect the AC bus voltage of the flexible DC power transmission system and further affect its power. Ignoring the controlled characteristics of the new energy is not only not conducive to guaranteeing the power output capacity of the flexible DC power transmission system during the fault, but also increases the risk of DC voltage out-of-limit. In addition, most of the existing researches cannot effectively reduce the load shedding. Excessive load shedding will cause energy loss, aggravate the thermal stress and electrical impact of the equipment, and increase the cost and risk of system operation.

[0005] In summary, although the existing technology solves the DC voltage control problem in the fault ride-through of the flexible DC power transmission system to a certain extent, it does not consider the influence of the controlled characteristics of the nearby new energy on the system during the fault, and often fails to effectively consider the influence of the new energy output on the power output of the receiving end converter station. In addition, the effectiveness and economy of the load shedding control strategy is still a problem to be solved. With the increasing demand for large-scale new energy grid connection, how to minimize the load shedding, reduce energy loss and improve the fault ride-through efficiency while ensuring the safety of the flexible DC power transmission system has become a difficult and key problem in current research. SUMMARY

[0006] In view of the above problems of the prior art, the present application provides a VSC-HVDC adaptive fault ride-through control method considering the influence of nearby new energy, which can dynamically adjust the control strategy of the receiving end converter station according to the severity of the fault and reasonably cooperate with load shedding, thereby guaranteeing the safety of the system while reducing the load shedding, reducing the energy loss of the system and improving the fault ride-through capability and the economy of the system operation.

[0007] In order to solve the above technical problems, the present application adopts the following technical scheme:

[0008] In the first aspect, the present application provides a VSC-HVDC adaptive fault ride-through control method considering the influence of nearby new energy, which is applied to a flexible DC power transmission system with new energy access in the nearby area, and includes the following steps:

[0009] S1, starting the fault ride-through control when the receiving end AC power grid of the flexible DC power transmission system fails;

[0010] S2, real-time acquisition of the AC bus voltage and current of the receiving end converter station under fault, calculation of the fault equivalent parameters of the receiving end AC power grid;

[0011] S3, solve the maximum fault allowable time of the receiving end converter station considering the influence of the new energy in the near area based on the fault equivalent parameters of the receiving end AC power grid;

[0012] S4, compare the main protection action time of the receiving end AC power grid with the maximum fault allowable time at the moment of fault occurrence; if the main protection action time is less than the maximum fault allowable time, execute step S5; otherwise, execute step S6;

[0013] S5, lock the outer loop control of the receiving end converter station, and set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum voltage operating point considering the influence of the new energy in the near area respectively; then, execute step S7;

[0014] S6, lock the outer loop control of the receiving end converter station, and set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area respectively, and at the same time, put into the first stage unloading power used to delay the overrunning time Then, execute step S7;

[0015] S7, detect whether the fault of the receiving end AC power grid is cleared at the expected action time of the main protection; if the fault is cleared, jump to step S9; if the fault is not cleared, continue to execute step S8;

[0016] S8, set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area respectively, and at the same time, put into the second stage unloading power P cp_T used to suppress the unbalanced power; then return to step S7;

[0017] S9, restore the outer loop control of the receiving end converter station, and exit the unloading, and the fault ride-through control is completed.

[0018] As a preferred scheme, in the step S2, the fault equivalent parameters of the receiving end AC power grid include an equivalent voltage source potential E E and a series impedance Z E , which are calculated in the following manner respectively:

[0019]

[0020] Wherein, R V.f and X V.f are an equivalent virtual short-circuit transient resistance and an equivalent virtual short-circuit transient reactance respectively, and the expression is:

[0021]

[0022] Wherein, X LEquivalent reactance of normal operation system; E S Grid voltage vector under normal operation; U rec.d , U rec.q are d, q axis components of AC bus voltage of receiving end converter station respectively; E S.d , E S.q are d, q axis components of grid voltage vector under normal operation respectively; I f,d and I f,q are active current and reactive current at AC bus outlet under grid fault respectively.

[0023] As a preferred solution, in step S3, the maximum fault allowable time of receiving end converter station considering the influence of new energy in the near area is calculated as follows:

[0024]

[0025] Wherein, T max is the maximum fault allowable time of receiving end converter station; U N , I N are rated voltage and rated current of grid respectively; C eq is DC capacitor of flexible HVDC transmission system; U dc.0 is DC voltage under normal operation; U dcN is rated DC voltage; K U is maximum allowable voltage coefficient; K is new energy reactive current coefficient; P dc is active power fed by DC line; R E and X E are resistance and reactance of series impedance Z E respectively; parameters B, C, A max are calculated as follows:

[0026]

[0027] C=(K I I rec.N ) 2 ;

[0028]

[0029] Wherein, I rec.N is rated AC current of receiving end converter station; K I is maximum allowable current coefficient of receiving end converter station; θ is phase angle difference between equivalent voltage of AC grid and AC bus voltage of receiving end converter station; E E is amplitude of equivalent voltage of fault AC grid; I d,w is active current corresponding to the maximum active operating point considering the influence of new energy in the near area, which is calculated as follows:

[0030]

[0031] As a preferred solution, in the step S5, the active current and the reactive current corresponding to the maximum voltage operating point considering the influence of the new energy in the near area are respectively calculated in the following manner:

[0032]

[0033] wherein I d,m and I q,m are the active current and the reactive current corresponding to the maximum voltage operating point considering the influence of the new energy in the near area; the parameter A is solved in the following manner:

[0034]

[0035] The parameter ζ satisfies |ζ|∈(0, K I I rec.N ), and is obtained by solving the following equation:

[0036]

[0037] T c is the fault duration, and the value is taken as the main protection action time T of the receiving end AC power grid, that is:

[0038] T c =T.

[0039] As a preferred solution, in the step S6, the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area are respectively calculated in the following manner:

[0040]

[0041] wherein I d,w and I q,w are the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area.

[0042] As a preferred solution, in the step S6, the first stage unloading power P for delaying the time of exceeding the limit is calculated in the following manner:

[0043]

[0044] wherein t0 is the fault time; P rec.max is the maximum active power output by the receiving end converter station corresponding to the maximum active operating point considering the influence of the new energy in the near area.

[0045] As a preferred solution, the maximum active power P rec.maxThe following applies:

[0046]

[0047] As a preferred solution, the second stage unloading power P cp_T The following applies:

[0048] P cp_T = P dc -P rec.max .

[0049] In a second aspect, the present application provides a VSC-HVDC adaptive fault ride-through control system considering the influence of new energy in the near area, comprising:

[0050] A starting module is configured to start the fault ride-through control when a fault occurs in the receiving end AC power grid of the flexible HVDC system;

[0051] An acquisition module is configured to acquire the AC bus voltage and current of the receiving end converter station in real time under the fault;

[0052] An equivalent parameter calculation module is configured to calculate the fault equivalent parameters of the receiving end AC power grid based on the AC bus voltage and current of the receiving end converter station;

[0053] A time calculation module is configured to solve the maximum fault allowable time of the receiving end converter station considering the influence of new energy in the near area based on the fault equivalent parameters of the receiving end AC power grid;

[0054] A comparison module is configured to compare the main protection action time of the receiving end AC power grid with the maximum fault allowable time at the moment of the fault; when the main protection action time is less than the maximum fault allowable time, the first control module is started, and when the main protection action time is greater than or equal to the maximum fault allowable time, the second control module is started;

[0055] The first control module is configured to, when the main protection action time is less than the maximum fault allowable time, lock the outer loop control of the receiving end converter station, and set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum voltage operating point considering the influence of new energy in the near area, respectively;

[0056] The second control module is configured to, when the main protection action time is greater than or equal to the maximum fault allowable time, lock the outer loop control of the receiving end converter station, and set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum active operating point considering the influence of new energy in the near area, respectively, and at the same time, input the first stage unloading power

[0057] A detection module is configured to detect whether the fault of the AC power grid at the receiving end is cleared at the main protection expected action time; if the fault is cleared, a recovery module is started; if the fault is not cleared, a third control module is started;

[0058] The third control module is configured to, when the fault is not cleared, keep the active current control reference value and the reactive current control reference value of the receiving end converter station at the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area, and put in the second stage unloading power P cp_T ;

[0059] The recovery module is configured to, when the fault is cleared, restore the outer loop control of the receiving end converter station and exit the unloading.

[0060] In a third aspect, the present application further provides a VSC-HVDC adaptive fault ride-through control device considering the influence of new energy in the near area, comprising 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 perform the VSC-HVDC adaptive fault ride-through control method considering the influence of new energy in the near area.

[0061] Compared with the prior art, the present application has the following beneficial effects:

[0062] 1. The present application fully considers the influence of new energy in the near area on the power of the receiving end converter station, quantifies the safety boundary of the receiving end converter station under the influence of new energy by establishing an analytical expression of the output current of the new energy and the power of the receiving end converter station, avoids overvoltage of the DC voltage under the influence of the fault current of the new energy, and effectively guarantees the stability and reliability of the system.

[0063] 2. The present application proposes a fault duration calculation method, based on the safety boundary of the receiving end converter station and the equivalent parameters of the power grid fault, solves the maximum fault allowable time of the receiving end converter station considering the influence of new energy in the near area, as an important basis for fault severity and subsequent control strategy making; according to different fault durations that may exist, the control strategy is flexibly adjusted to determine whether unloading needs to be started or control parameters need to be adjusted, thereby improving the fault ride-through capability of the system.

[0064] 3. The adaptive control strategy proposed by the present application enables the system to dynamically adjust the control strategy according to different types and durations of faults, flexibly adjusts the power output of the receiving end converter station during the fault, realizes reasonable cooperation of unloading, ensures to reduce the dependence on unloading, reduces the energy loss of the system, thereby improving the efficiency and adaptability of fault ride-through.

[0065] 4、The scheme not only improves the fault ride-through capability of the flexible HVDC power transmission system containing new energy access in the near area, ensures reliable operation under complex fault conditions, but also significantly improves the economy of system operation, and provides strong technical support for stable operation of the flexible HVDC power transmission system in the new energy access scene. BRIEF DESCRIPTION OF DRAWINGS

[0066] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be further described in detail below with reference to the drawings, in which:

[0067] Figure 1 The flow chart of the VSC-HVDC adaptive fault ride-through control method considering the influence of new energy in the near area provided by the application;

[0068] Figure 2 The framework schematic diagram of the VSC-HVDC adaptive fault ride-through control system considering the influence of new energy in the near area provided by the application;

[0069] Figure 3 The simulation system example schematic diagram of the flexible HVDC power transmission system containing new energy access in the near area of the embodiment of the application;

[0070] Figure 4 The curve diagram of the electrical quantity of the receiving end converter station and the receiving end power grid in the first embodiment scheme of the embodiment of the application;

[0071] Figure 5 The curve diagram of the electrical quantity of the receiving end converter station and the receiving end power grid in the second embodiment scheme of the embodiment of the application;

[0072] Figure 6 The curve diagram of the electrical quantity of the receiving end converter station and the receiving end power grid in the third embodiment scheme of the embodiment of the application. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be further described in detail below with reference to the drawings, in which:

[0074] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0075] In a first aspect, the present application provides a VSC-HVDC adaptive fault ride-through control method considering the influence of new energy in the near area, which is applied to a flexible HVDC transmission system with new energy access in the near area. The method considers the influence of the fault response of new energy in the near area on the controllable range of the AC current of the receiving end converter station, and realizes the improvement of the active power output of the receiving end converter station of the flexible HVDC transmission system during the fault of the receiving end AC grid and the reduction of the DC dump power through the switching of the current reference value of the receiving end converter station and the cooperation of the dump.

[0076] Based on the above technical design idea, the VSC-HVDC adaptive fault ride-through control method considering the influence of new energy in the near area has a specific process as shown in Figure 1 The method comprises the following steps:

[0077] S1, when a fault occurs in the receiving end AC grid of the flexible HVDC transmission system, starting the fault ride-through control;

[0078] S2, real-time acquisition of the AC bus voltage and current of the receiving end converter station under fault, calculation of the fault equivalent parameters of the receiving end AC grid;

[0079] S3, based on the fault equivalent parameters of the receiving end AC grid, solving the maximum fault allowable time of the receiving end converter station considering the influence of new energy in the near area;

[0080] S4, comparing the main protection action time of the receiving end AC grid with the maximum fault allowable time at the moment of fault occurrence; if the main protection action time is less than the maximum fault allowable time, executing step S5; otherwise, executing step S6;

[0081] S5, locking the outer ring control of the receiving end converter station, and setting the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum voltage operating point considering the influence of new energy in the near area respectively; then, executing step S7;

[0082] S6, locking the outer ring control of the receiving end converter station, and setting the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum active operating point considering the influence of new energy in the near area respectively, and at the same time, putting into the first stage of dump power used to delay the time of exceeding the limit Then, executing step S7;

[0083] S7, detecting whether the fault of the receiving end AC power grid is cleared at the main protection expected action moment; if the fault is cleared, jumping to step S9; if the fault is not cleared, continuing to execute step S8;

[0084] S8, setting the active current control reference value and the reactive current control reference value of the receiving end converter station as the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area, and simultaneously inputting the second stage unloading power P cp_T to suppress the unbalanced power; and then returning to step S7;

[0085] S9, restoring the outer loop control of the receiving end converter station, and exiting the unloading, and the fault ride-through control is completed.

[0086] It can be seen from the above process that, after the fault of the receiving end AC power grid of the flexible HVDC power transmission system occurs and the fault ride-through control is started, the maximum fault allowable time of the receiving end converter station considering the influence of the new energy in the near area is solved according to the real-time fault equivalent parameters, which is used as an important basis for the fault severity and the subsequent control strategy; thereafter, the control strategy is flexibly adjusted by comparing the relationship between the main protection action time and the maximum fault allowable time, and it is determined whether the unloading needs to be started or the control parameters need to be adjusted according to the fault severity, until the fault is cleared, thereby improving the fault ride-through capability of the system. Thus, through the method of the present application, the system can dynamically adjust the control strategy according to different types and durations of faults, realize the reasonable cooperation of unloading, ensure to reduce the dependence on unloading input, reduce the energy loss of the system, and thereby improve the efficiency and adaptability of the fault ride-through. Therefore, the method of the present application not only improves the fault ride-through capability of the flexible HVDC power transmission system with new energy access in the near area, ensures reliable operation under complex fault conditions, but also significantly improves the economy of system operation, and provides strong technical support for the stable operation of the flexible HVDC power transmission system in the new energy access scenario.

[0087] In a specific application implementation, a three-phase short-circuit fault occurring at an arbitrary position of the power grid is equivalent to a virtual short-circuit fault occurring at an AC bus, and it is assumed that the AC bus voltage and current of the receiving end converter station remain unchanged during the fault process. Through this equivalent model, the influence of the power grid fault on the AC bus voltage of the receiving end converter station can be simulated. In the calculation process, the equivalent virtual short-circuit transition impedance is introduced, and the virtual fault transition resistance and reactance are derived through the electrical characteristics of the power grid fault. At this time, the grid potential vector under normal operation and the voltage component of the AC bus of the receiving end converter station will be used to derive the equivalent electrical characteristics of the fault grid. Specifically, the calculation will calculate the transition resistance and reactance of the virtual fault through the node voltage equation according to the actual situation of the power grid fault. By simplifying the fault grid by using Thevenin equivalent circuit, the equivalent potential and impedance of the fault grid are finally obtained.

[0088] In a specific application implementation, the fault equivalent parameters of the receiving end alternating current power grid include an equivalent voltage source potential E E , a series impedance Z E , which are respectively calculated in the following manner:

[0089]

[0090] wherein R V.f and X V.f are respectively an equivalent virtual short-circuit transient resistance and an equivalent virtual short-circuit transient reactance of a three-phase short-circuit fault at an alternating current bus, which are solved by a node voltage equation of the equivalent network at the alternating current bus of the receiving end converter station, and respective expressions are as follows:

[0091]

[0092] wherein X L is an equivalent reactance of the system in normal operation; E S is a grid potential vector in normal operation; U rec.d and U rec.q are respectively a d-axis component and a q-axis component of the alternating current bus voltage of the receiving end converter station; E S.d and E S.q are respectively a d-axis component and a q-axis component of the grid potential vector in normal operation; I f,d and I f,q are respectively an active current and a reactive current at an outlet of the alternating current bus under a grid fault.

[0093] In a specific application implementation, the maximum fault allowable time of the receiving end converter station considering the influence of the near-zone new energy is a longest fault duration that can avoid over-limit of the direct current voltage only by control of the receiving end converter station under variation of the new energy output current with the terminal voltage. In specific calculation, it is considered that, under a grid fault, current control of the receiving end converter station is limited by a direct current voltage boundary and an alternating current boundary, and as the fault duration increases, the safe boundary of the direct current voltage moves to a positive direction of the longitudinal coordinate, resulting in reduction of the safe domain, and the fault time corresponding to tangency of the two boundaries is the maximum fault allowable time.

[0094] In some application working conditions, the maximum fault allowable time of the receiving end converter station considering the influence of the near-zone new energy is a longest fault duration that can avoid over-limit of the direct current voltage only by control of the receiving end converter station under variation of the new energy output current with the terminal voltage, which is calculated in the following manner:

[0095]

[0096] wherein T max is the maximum fault allowable time of the receiving end converter station; U N and I Nrespectively, rated voltage and rated current of power grid; C eq is DC capacitor of flexible HVDC system; U dc.0 is DC voltage in normal operation; U dcN is rated DC voltage; K U is maximum allowable voltage coefficient; K is new energy reactive current coefficient; P dc is active power fed into DC line; R E and X E are resistance and reactance of series impedance Z E , respectively.

[0097] Parameters B, C, A max are current parameter abbreviations, which are calculated by the following ways, respectively:

[0098]

[0099] C = (K I I rec.N ) 2 ;

[0100]

[0101] In the formula, I rec.N is rated AC current of receiving end converter station; K I is maximum allowable current coefficient of receiving end converter station; θ is phase angle difference between AC power grid equivalent potential and AC bus voltage of receiving end converter station; E E is amplitude of fault AC power grid equivalent potential; I d,w is active current corresponding to maximum active operating point considering the influence of new energy in the vicinity, which is calculated in the following way:

[0102]

[0103] In some application conditions, the active current and reactive current corresponding to the maximum voltage operating point considering the influence of new energy in the vicinity can support the AC bus voltage to the maximum extent on the premise of ensuring the safety of the receiving end converter station. By considering the relationship among fault duration, main protection action time and new energy output current, the active current reference value and the reactive current reference value of the maximum voltage operating point can be calculated. At this time, specifically, the active current and the reactive current corresponding to the maximum voltage operating point considering the influence of new energy in the vicinity are calculated in the following ways, respectively:

[0104]

[0105] In the formula, I d,m and I q,m are active current and reactive current corresponding to the maximum voltage operating point considering the influence of new energy in the vicinity, respectively.

[0106] The parameter A is solved in the following way:

[0107]

[0108] The parameter ζ satisfies |ζ|∈(0, K I I rec.N and is obtained by solving the following equation:

[0109]

[0110] T c is the fault duration, which is taken as the main protection action time T of the receiving end AC power grid, i.e.,

[0111] T c = T.

[0112] In other application conditions, when considering power grid faults, the current control of the receiving end converter station is limited by the DC voltage boundary and the AC current boundary. As the fault duration increases, the DC voltage safety boundary moves to the positive direction of the longitudinal coordinate, resulting in a decrease in the safety domain. The tangent point when the two boundaries are tangent is the maximum active power operating point. At this time, the active current and the reactive current corresponding to the maximum active power operating point considering the influence of the new energy in the near area can make the receiving end converter station output the maximum active power to reduce the DC unbalanced power, while delaying the DC voltage overrun time, which is calculated in the following way:

[0113]

[0114] In the formula, I d,w and I q,w are the active current and the reactive current corresponding to the maximum active power operating point considering the influence of the new energy in the near area.

[0115] Under this condition, when the maximum allowed fault time is less than the main protection action time, the safety domain does not exist, and it is impossible to avoid the DC voltage overrun only by relying on the control of the receiving end converter station before the fault is removed. In this case, it is necessary to put in the load shedding to balance the unbalanced power of the DC line. During the fault, the input of the load shedding should be avoided or reduced as much as possible. The system controls the operating point of the receiving end converter station to the maximum active power operating point, and determines the appropriate load shedding input on this basis to delay the DC voltage overrun time to the main protection action time. Therefore, under this condition, the first stage load shedding power is put in to cooperate with the converter station control to delay the DC voltage overrun time to the main protection action time, which plays a role in delaying the overrun time. The first stage load shedding power is calculated in the following way:

[0116]

[0117] where t0 is the fault time; Prec.max To account for the maximum active operating point corresponding to the maximum active power output of the receiving end converter station under the influence of new energy in the near zone, the following method is used for calculation:

[0118]

[0119] In some other application conditions, the main protection may fail to act, resulting in the fault being removed by the backup protection. At the time when the main protection should act, if the main protection fails to act successfully, the receiving end converter station outputs the maximum active power, and the unloading is appropriately increased to completely suppress the unbalanced power and prevent the DC voltage from exceeding the limit.

[0120] In this condition, the second stage unloading power P cp_T is used to completely suppress the unbalanced power, which is calculated in the following manner:

[0121] P cp_T = P dc -P rec.max .

[0122] In a second aspect, the present application provides a VSC-HVDC adaptive fault ride-through control system considering the influence of new energy in the near zone, the system architecture is as shown in Figure 2 , and includes:

[0123] A starting module is configured to start the fault ride-through control when a fault occurs in the receiving end AC power grid of the flexible DC power transmission system.

[0124] An acquisition module is configured to acquire the AC bus voltage and current of the receiving end converter station in real time under the fault.

[0125] An equivalent parameter calculation module is configured to calculate the fault equivalent parameters of the receiving end AC power grid based on the AC bus voltage and current of the receiving end converter station.

[0126] A time calculation module is configured to solve the maximum fault allowable time of the receiving end converter station considering the influence of new energy in the near zone based on the fault equivalent parameters of the receiving end AC power grid.

[0127] A comparison module is configured to compare the main protection action time of the receiving end AC power grid with the maximum fault allowable time at the time when the fault occurs, start the first control module when the main protection action time is less than the maximum fault allowable time, and start the second control module when the main protection action time is greater than or equal to the maximum fault allowable time.

[0128] The first control module is configured to, when the main protection action time is less than the maximum fault allowable time, lock the outer loop control of the receiving end converter station, and set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum voltage operating point considering the influence of new energy in the near zone, respectively.

[0129] a second control module, configured to, when the main protection action time is greater than or equal to the maximum fault allowable time, lock the outer loop control of the receiving end converter station, set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area respectively, and input the first stage unloading power

[0130] a detection module, configured to, when the main protection expected action time, detect whether the fault of the receiving end AC power grid is cleared; if the fault is cleared, start the recovery module; if the fault is not cleared, start the third control module;

[0131] a third control module, configured to, when the fault is not cleared, keep the active current control reference value and the reactive current control reference value of the receiving end converter station at the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area, and input the second stage unloading power P cp_T

[0132] a recovery module, configured to, when the fault is cleared, restore the outer loop control of the receiving end converter station, and exit the unloading.

[0133] The VSC-HVDC adaptive fault ride-through control system of the application is combined by the starting module, the acquisition module, the equivalent parameter calculation module, the time calculation module, the comparison module, the control module, the detection module and the recovery module, calculates the maximum fault allowable time of the receiving end converter station, and adjusts the control strategy of the receiving end converter station according to the fault condition. By reasonably selecting the first control module and the second control module when the fault occurs, flexibly adjusting the active current reference value and the reactive current reference value of the receiving end converter station according to the comparison result of the main protection action time and the maximum fault allowable time, the DC voltage of the power grid is ensured not to exceed the limit. At the same time, the detection module detects the main protection expected action time, and the recovery module or the third control module is started according to the fault clearing condition, so as to ensure the recovery of the control strategy after the fault is cleared, and further ensure the safety of the DC voltage and the AC current through the second stage unloading control. The VSC-HVDC adaptive fault ride-through control system thus constructed can well cooperate with the VSC-HVDC adaptive fault ride-through control method of the application, can realize reasonable cooperation of unloading, can ensure to reduce the dependence on unloading input, can reduce system energy loss, can avoid energy loss and equipment damage caused by high-power unloading, and thus can improve the economy and reliability of the system during the fault period.

[0134] ​In a third aspect, the present application also provides a VSC-HVDC adaptive fault ride-through control device considering the influence of new energy in the near area, comprising 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 VSC-HVDC adaptive fault ride-through control method considering the influence of new energy in the near area when executing the computer program.

[0135] The memory can be any combination of one or more computer readable medium. The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium can include an electronic, magnetic, optical, electromagnetic, infrared, semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a computer readable storage medium can include a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the present application, a computer readable storage medium can be any tangible medium that includes or stores a program, which can be used by or in connection with an instruction execution system, apparatus, or device.

[0136] The code for the computer program to perform the present application can be written in one or more programming languages or combinations of languages including object oriented programming languages, such as Java, Smalltalk, C++, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network or a wide area network, or the connection can be made to an external computer.

[0137] Embodiment:

[0138] To verify the effectiveness of the method of the present application, the simulation system of the flexible DC transmission system with new energy access in the near area shown in FIG. 1 is taken as an example to verify the correctness of the theoretical analysis. As shown in FIG. 2, the simulation system of the flexible DC transmission system with new energy access in the near area is taken as an example to verify the correctness of the theoretical analysis. Figure 3 Figure 3 ​The receiving end power grid adopts a 2-area 4-machine system in the illustrated simulation system. The flexible HVDC transmission system adopts a pseudo bipolar structure, with a rated voltage of ±100 kV, a rated transmission capacity of 200 MVA, a maximum allowable voltage coefficient of 1.1, and a maximum allowable current coefficient of 1.2. The SEC adopts fixed active and reactive power control, with an active power reference value of 200 MW and a reactive power reference value of 0 Mvar. In normal operation, the receiving end converter station adopts fixed DC voltage and reactive power control, with a DC voltage reference value of 100 kV and a reactive power reference value of 0 Mvar. The main protection of the AC power grid has an action time of 0.1 s, and the backup protection has an action time of 0.5 s. A centralized DC dump is adopted, and the dumps in the comparison group are all put into operation when the DC voltage reaches 1.1 p.u., with a maximum dump power of 0.6 p.u.

[0139] Three scenarios are designed according to the relationship between the fault limit removal time and the protection action time, and the following three control methods are compared: Control method 1 (Method 1) refers to the new energy fault ride-through requirement, and controls the output of the reactive power of the receiving end converter station according to the voltage drop degree. Control method 2 (Method 2) determines the active and reactive power control reference values of the receiving end converter station according to the DC voltage and AC current constraints of the receiving end converter station, with the longest time of power imbalance as the condition, without considering the cooperation between the receiving end converter station control and the dump, and without considering the influence of the near-zone new energy. Control method 3 (Method 3) is the self-adaptive fault ride-through control method proposed in the application.

[0140] Scheme one: the fault limit removal time is greater than the main protection action time and the main protection correctly acts

[0141] A three-phase short-circuit fault occurs at a distance of 0.56 times the total length of the line from the connecting transformer at 0.5 s, and the main protection correctly acts. At the moment of the fault, the voltage of the receiving end converter station AC bus drops to 0.7 p.u. The fault equivalent impedance of the receiving end AC power grid is 14.1+j9.9 Ω. According to the grid-connected point voltage, the active and reactive current reference values of Method 1 are 1.03 p.u. and 0.51 p.u. respectively; the active and reactive current reference values of Method 2 are 1.05 p.u. and 0.42 p.u. respectively. The fault limit removal time can be calculated as 0.112 s, which is greater than the main protection action time 0.1 s, so Method 3 controls the active and reactive currents in the safe domain to output the operating point m(I dm ,I qm ) with the maximum reactive power, which are 1.10 p.u. and 0.38 p.u. respectively. The electrical quantities of the receiving end converter station and the receiving end power grid under the three methods are shown in Figure 4 Method 1, Method 2, and Method 3 correspond to the curves shown in the figure.

[0142] Under Method 1, the AC bus voltage is 0.78 p.u. after the fault. However, due to the small output active current, the active power of the receiving converter station is greatly reduced, being only 0.71 p.u. during the fault, which causes the DC voltage to rise to 1.1 p.u. at 0.52 s. To avoid overvoltage, the unloading of 0.6 p.u. is put into operation at this time. Method 2 takes into account both the AC bus voltage support and the DC unbalanced power reduction, so the AC bus voltage after the fault is slightly lower than that of Method 1, being 0.76 p.u., but the active power output is increased to 0.75 p.u. At 0.56 s, the DC voltage still rises to 1.1 p.u., causing the unloading to be put into operation. Under Method 3, the AC voltage is 0.75 p.u. after the fault, but the active power reaches 0.82 p.u., which is greater than that of Methods 1 and 2. Therefore, the DC voltage rises at a slower rate under Method 3 than under Methods 1 and 2 during the fault. At the time of the main protection action, the DC voltage of Method 3 is about 1.09 p.u., and the unloading does not need to be put into operation to ensure the safety of the DC voltage.

[0143] Scheme II: Fault limit removal time is greater than the main protection action and the main protection refuses to act

[0144] The fault location is unchanged, but the main protection refuses to act at 0.1 s after the fault, and the fault is cleared by the backup protection at 0.5 s after the fault. The equivalent fault resistance is 14.1 + j9.9 Ω. The active and reactive current reference values of Method 1 are 1.03 p.u. and 0.51 p.u., respectively; the active and reactive current reference values of Method 2 are 1.05 p.u. and 0.42 p.u., respectively; and the fault limit removal time can be calculated to be 0.112 s, which is greater than the main protection action time of 0.1 s. Therefore, at the fault occurrence time, the active and reactive currents of Method 3 are controlled to output the operating point m(I dm ,I qm ) with the maximum reactive power in the safe domain, which are 1.10 p.u. and 0.38 p.u., respectively. The electrical quantities of the receiving converter station under the three different control methods are shown in Figure 5 Fig. 4, where the curves corresponding to Method 1, Method 2, and Method 3 are shown.

[0145] Method 1 causes the DC voltage to reach 1.1 p.u. for the first time at 0.56 s after the fault, and the unloading is put into operation. During the fault, the unbalanced energy stored in the DC capacitor is released through the unloading, the DC voltage decreases, and until 0.62 s, the DC voltage returns to 1.0 p.u., and the unloading is withdrawn. At this time, the fault is not removed, and the unbalanced energy continues to charge the capacitor, causing the unloading to be repeatedly put into operation. Method 2 is similar to Method 1, and the unloading is put into operation 4 times during the fault. As shown inFigure 5 (B) shows, the total unloading time of Method 1 and Method 2 is 0.30s and 0.21s respectively, and the average unloading power during the fault is 0.33p.u. and 0.23p.u. respectively. Within 0.1s after the fault, the active and reactive current of Method 3 is controlled to point c (I dm ,I qm ), at this time the AC voltage is 0.75p.u. and the active power is 0.82p.u.. After 0.1s of the fault, the DC voltage is not restored, the active and reactive current reference value of the lower end converter station in Method 3 is switched to 1.13p.u. and 0.32p.u. respectively, and the unloading is put in. As shown in (E) and (F), at this time the active and reactive power output by the lower end converter station is 0.87p.u. and 0.30p.u. respectively. The active power output by the lower end converter station in Method 3 is increased, which reduces the unbalanced energy of the DC capacitor, and the DC voltage rises more gently. Only 3 times of unloading is put in during the fault, the unloading time is reduced to 0.13s, and the average unloading power during the fault is reduced to 0.14p.u.. Figure 5 (E) and Figure 5 (F) shows, at this time the active and reactive power output by the lower end converter station is 0.87p.u. and 0.30p.u. respectively. The active power output by the lower end converter station in Method 3 is increased, which reduces the unbalanced energy of the DC capacitor, and the DC voltage rises more gently. Only 3 times of unloading is put in during the fault, the unloading time is reduced to 0.13s, and the average unloading power during the fault is reduced to 0.14p.u..

[0146] Scheme three: the fault limit removal time is less than the main protection action time

[0147] A three-phase short-circuit fault occurs at a distance of 0.25 times the total length of the line from the coupling transformer at 0.5s, and the main protection correctly acts. At the moment of the fault, the AC bus voltage of the lower end converter station drops to 0.6p.u.. The fault equivalent impedance is 10.5+j4.3Ω. The electrical quantities of the lower end converter station under the control of three different methods are shown in the curves corresponding to Method 1, Method 2 and Method 3. Figure 6 Method 1 and Method 2. The active current of the lower end converter station under Method 1 and Method 2 is 1.02p.u. and 1.03p.u. respectively, and the reactive current is 0.67p.u. and 0.55p.u. respectively. Under Method 1 and Method 2, the AC bus voltage after the fault is 0.68p.u. and 0.65p.u. respectively, the active power is 0.61p.u. and 0.65p.u. respectively, and the DC voltage rises to 1.1p.u. at 0.05s and 0.07s respectively after the fault. Both methods need to put in 0.6p.u. unloading until the end of the fault.

[0148] The fault limit removal time can be calculated as 0.074s, which is less than the main protection action time 0.1s. Therefore, the active and reactive current of the lower end converter station is controlled to point c (I dc ,I qcThe power outputs are 1.06 pu and 0.51 pu respectively, with an additional 0.11 pu unloading power applied at the moment of failure. For example... Figure 6 As shown, under Method 3, the bus AC voltage is 0.63 pu. Initially, 0.11 pu is unloaded, slowing the DC voltage rise rate. Within 0.1 seconds after the fault, the DC voltage does not exceed 1.1 pu until the main protection trips, clearing the fault and restoring the DC voltage. Under Method 3, the bus AC voltage is only reduced by 0.05 pu and 0.02 pu compared to Method 1 and Method 2, respectively, but the average unloading power is reduced by 0.47 pu, alleviating the short-term unloading heat dissipation pressure. Simultaneously, under Method 3, the active power output of the receiving-end converter station is 0.71 pu, which is 0.1 pu and 0.06 pu higher than under Method 1 and Method 2, respectively, improving the active power output capability of the receiving-end converter station under fault conditions.

[0149] In summary, compared with the prior art, the present invention has the following technical advantages:

[0150] 1. This invention fully considers the impact of nearby renewable energy sources on the power of the receiving-end converter station. By establishing analytical expressions for the output current of renewable energy sources and the power of the receiving-end converter station, the safety boundary of the receiving-end converter station under the influence of renewable energy sources is quantified, avoiding DC voltage exceeding the limit under the influence of renewable energy fault current, and effectively ensuring the stability and reliability of the system.

[0151] 2. This invention proposes a method for calculating fault duration. Based on the safety boundary of the receiving-end converter station and the equivalent parameters of the power grid fault, the maximum allowable fault time of the receiving-end converter station, taking into account the impact of nearby renewable energy sources, is calculated. This serves as an important basis for the severity of the fault and the subsequent formulation of control strategies. According to the different possible fault durations, the control strategy can be flexibly adjusted to determine whether it is necessary to start unloading or adjust the control parameters, thereby improving the fault ride-through capability of the system.

[0152] 3. The adaptive control strategy proposed in this invention enables the system to dynamically adjust the control strategy according to different types and durations of faults. During a fault, the system can flexibly adjust the power output of the receiving-end converter station to achieve reasonable coordination of unloading, ensure reduced dependence on unloading input, reduce system energy loss, and thus improve the efficiency and adaptability of fault ride-through.

[0153] 4. The present invention not only improves the fault ride-through capability of flexible DC transmission systems with new energy access in the near-field area, ensuring reliable operation under complex fault conditions, but also significantly improves the economic efficiency of system operation, providing strong technical support for the stable operation of flexible DC transmission systems in new energy access scenarios.

[0154] Finally, it should be noted that the above examples are intended to illustrate the technical solutions of the present application but not to limit the technical solutions. Those of ordinary skill in the art should understand that modifications or equivalent replacements to the technical solutions of the present application can be made without departing from the purpose and scope of the technical solutions, and all should be covered within the scope of the claims of the present application.

Claims

1. A VSC-HVDC adaptive fault ride-through control method considering the influence of new energy in the near zone, applied to a flexible HVDC transmission system with new energy access in the near zone, characterized in that, The method comprises the following steps: S1, when a fault occurs in an AC power grid at a receiving end of a flexible HVDC power transmission system, starting fault ride-through control; S2, collecting AC bus voltage and current of a receiving end converter station in real time under the fault, and calculating fault equivalent parameters of the AC power grid at the receiving end; S3, based on the fault equivalent parameters of the AC power grid at the receiving end, solving maximum fault allowable time of the receiving end converter station considering the influence of new energy in a near region; S4, comparing a main protection action time of the AC power grid at the receiving end with the maximum fault allowable time at a fault occurrence time; if the main protection action time is less than the maximum fault allowable time, executing step S5; otherwise, executing step S6; S5, locking outer loop control of the receiving end converter station, and setting active current control reference value and reactive current control reference value of the receiving end converter station to active current and reactive current corresponding to a maximum voltage operating point considering the influence of new energy in the near region respectively; then, executing step S7; S6, the slave converter station is locked out of the outer loop control, and the active current control reference value and the reactive current control reference value of the slave converter station are set to the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area, and the first stage unloading power used to delay the time of exceeding the limit is put into operation Then, step S7 is performed. S7, at a main protection expected action time, detecting whether the fault of the AC power grid at the receiving end is cleared; if the fault is cleared, jumping to step S9; if the fault is not cleared, continuing to execute step S8; S8, set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area, and simultaneously input the second stage unloading power P cp_T ; and then return to step S7; S9, restoring the outer loop control of the receiving end converter station, and exiting unloading, and the fault ride-through control is completed.

2. The VSC-HVDC adaptive fault ride through control method considering the influence of new energy in the near zone according to claim 1, characterized in that, In the step S2, the fault equivalent parameters of the receiving AC power grid comprise an equivalent voltage source potential E E , a series impedance Z E , respectively calculated as follows: wherein R V.f , X V.f are the equivalent virtual short-circuit transition resistance, the equivalent virtual short-circuit transition reactance, respectively, and the expression is: where X L is the system equivalent reactance during normal operation; E S is the grid voltage vector during normal operation; U rec.d , U rec.q are the d, q-axis components of the AC bus voltage at the receiving end converter station, respectively; E S.d , E S.q are the d, q-axis components of the grid voltage vector during normal operation, respectively; I f,d and I f,q are the active and reactive currents at the AC bus outlet during grid fault, respectively.

3. The VSC-HVDC adaptive fault ride through control method considering the influence of new energy in the near zone according to claim 1, characterized in that, In the step S3, the maximum fault allowable time of the receiving end converter station considering the influence of new energy in the near region is calculated in the following manner: Wherein, T max is the maximum fault allowable time of the receiving converter station; U N , I N are the rated voltage and the rated current of the power grid respectively; C eq is the DC capacitor of the flexible HVDC power transmission system; U dc.0 is the DC voltage in normal operation; U dcN is the rated DC voltage; K U is the maximum allowable voltage coefficient; K is the new energy reactive current coefficient; P dc is the active power fed into the DC line; R E and X E are the resistance and the reactance of the series impedance Z E respectively; the parameters B, C, A max are calculated by the following ways respectively: C = (K I I rec.N ) 2 ; where I rec.N is the rated AC current of the receiving converter station; K I is the maximum allowable current coefficient of the receiving converter station; θ is the phase angle difference between the equivalent AC potential of the AC power grid and the AC bus voltage of the receiving converter station; E E is the amplitude of the equivalent AC potential of the fault AC power grid; I d,w is the active current corresponding to the maximum active operating point considering the influence of the new energy in the vicinity, and is calculated as follows:

4. The VSC-HVDC adaptive fault ride through control method considering the influence of new energy in the near zone according to claim 3, characterized in that, In the step S5, the active current and the reactive current corresponding to the maximum voltage operating point considering the influence of new energy in the near region are calculated in the following manner respectively: Among them, I d,m I q,m These are the active current and reactive current corresponding to the maximum voltage operating point, taking into account the impact of nearby renewable energy sources; parameter A is solved as follows: The parameter ζ satisfies |ζ| ∈ (0, K I I rec.N ), is obtained by solving the following equation: T c The fault duration is taken as the value of the main protection action time T of the receiving end AC power grid, i.e. T c = T.

5. The VSC-HVDC adaptive fault ride through control method considering the influence of new energy in the near zone according to claim 3, characterized in that, In the step S6, the active current and the reactive current corresponding to the maximum active operating point considering the influence of new energy in the near region are calculated in the following manner respectively: In the formula, I d,w , I q,w are active current and reactive current corresponding to the maximum active operating point considering the influence of new energy in the near zone, respectively.

6. The VSC-HVDC adaptive fault ride through control method considering the influence of new energy in the near zone according to claim 4 or 5, characterized in that, The first stage of offload power to defer the time of exceeding the limit in the step S6 This is calculated as follows: Where t0 is the fault time; P rec.max is the maximum active power output of the receiving end converter station corresponding to the maximum active operating point considering the influence of new energy in the vicinity.

7. The VSC-HVDC adaptive fault ride through control method considering the influence of new energy in the near zone according to claim 6, characterized in that, The maximum active operation point considering the influence of new energy in the near zone corresponds to the output maximum active power P of the receiving end converter station rec.max This is calculated as follows: 8.The VSC-HVDC adaptive fault ride-through control method considering the influence of new energy in the near zone of claim 6, wherein, The second stage unloading power P cp_T is calculated in the following way: P cp_T = P dc - P rec.max . 9.A VSC-HVDC adaptive fault ride-through control system considering the influence of new energy in the near zone, characterized in that, The method comprises the following steps: a starting module, configured to start fault ride-through control when a fault occurs in an AC power grid at a receiving end of a flexible HVDC power transmission system; an obtaining module, configured to collect AC bus voltage and current of a receiving end converter station in real time under the fault; an equivalent parameter calculation module, configured to calculate fault equivalent parameters of the AC power grid at the receiving end based on the AC bus voltage and current of the receiving end converter station; a time calculation module, configured to solve maximum fault allowable time of the receiving end converter station considering the influence of new energy in a near region based on the fault equivalent parameters of the AC power grid at the receiving end; a comparison module, configured to compare a main protection action time of the AC power grid at the receiving end with the maximum fault allowable time at a fault occurrence time; a first control module is started when the main protection action time is less than the maximum fault allowable time, and a second control module is started when the main protection action time is greater than or equal to the maximum fault allowable time; the first control module is configured to lock outer loop control of the receiving end converter station, and set active current control reference value and reactive current control reference value of the receiving end converter station to active current and reactive current corresponding to a maximum voltage operating point considering the influence of new energy in the near region when the main protection action time is less than the maximum fault allowable time; The second control module is configured to, when the main protection action time is greater than or equal to the maximum fault allowable time, lock the outer loop control of the receiving end converter station, set the active current control reference value and the reactive current control reference value of the receiving end converter station to the active current and the reactive current corresponding to the maximum active operating point considering the influence of the new energy in the near area respectively, and simultaneously input the first stage unloading power a detection module, configured to detect whether the fault of the AC power grid at the receiving end is cleared at a main protection expected action time; if the fault is cleared, a restoration module is started; if the fault is not cleared, a third control module is started; The third control module is configured to, when the fault is not cleared, keep the active current control reference value and the reactive current control reference value of the receiving end converter station at the active current and the reactive current corresponding to the maximum active operation point considering the influence of the new energy in the near area, and to put in the second stage unloading power P cp_T ; the restoration module is configured to restore the outer loop control of the receiving end converter station and exit unloading when the fault is cleared.

10. A VSC-HVDC adaptive fault ride through control device considering the influence of new energy in the near zone, characterized in that, The application relates to a computer program product comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, executes the adaptive VSC-HVDC fault ride-through control method considering the influence of new energy in a near zone according to any one of claims 1 to 8.

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