Test methods, apparatus and related equipment for over-protection of temporary lockout of flexible direct current valve control

Abstract

This application discloses a method, apparatus, and related equipment for testing flexible DC valve-controlled temporary blocking over-protection. The method includes: determining a set of operating conditions based on the main circuit topology of a flexible DC system simulation model; determining multiple consecutive fault operating conditions according to the criteria and settings of the flexible DC valve-controlled temporary blocking over-protection, and each operating condition in the set of operating conditions; triggering each of the consecutive fault operating conditions one by one in the flexible DC system simulation model, acquiring waveform data in the flexible DC system simulation model, and determining whether the flexible DC valve-controlled temporary blocking over-protection responds according to the design principles; if the flexible DC valve-controlled temporary blocking over-protection fails to respond according to the design principles, it is determined that the flexible DC valve-controlled temporary blocking over-protection has failed the test. The method is simple to operate, has good versatility and strong applicability, and can effectively perform functional testing on flexible DC valve-controlled temporary blocking over-protection.

Description

Technical Field

[0001] This application relates to the field of power system fault technology, and more specifically, to a method, apparatus and related equipment for testing temporary blocking protection of flexible DC valve control. Background Technology

[0002] Modular multilevel converters (MMCs) offer advantages such as modular design, high scalability, flexible four-quadrant power operation, low AC voltage harmonics, and small footprint. In recent years, they have been widely researched and utilized in areas such as asynchronous interconnection of AC power grids and wind farm integration. In practical applications, several completed projects in my country have adopted MMC topologies.

[0003] As a voltage source converter, to prevent overcurrent damage to fully controlled power electronic devices such as IGBTs (Insulated Gate Bipolar Transistors), the flexible DC valve control system is equipped with temporary lockout protection. This protection is fast-acting; when the flexible DC valve control detects that the arm current exceeds a set value and meets the action delay, it briefly locks the converter valve; when the flexible DC valve control detects that the arm current is less than the return value and meets the return delay, it unlocks the converter valve again. Simultaneously, to prevent multiple stress impacts on the converter valve and IGBTs caused by repeated temporary lockouts within a short period, the flexible DC valve control system is also equipped with a temporary lockout over-limit protection function. The principle of this function is: if the number of temporary lockouts reaches a set number within a set time, the temporary lockout over-limit protection will trip.

[0004] To reliably assess and verify the rationality of the criteria and settings for the temporary blocking over-circuit protection of the flexible DC valve control system, it is necessary to test this function. Due to the extremely high safety and stability requirements of power systems, it is impossible to conduct testing of this protection in actual systems. Traditional dynamic simulation tests suffer from drawbacks such as limitations in simulation scale due to site constraints, complex wiring, poor scalability, and limited testing capabilities. Therefore, simulation tools are often required for testing. However, the temporary blocking over-circuit protection is a backup protection for the MMC converter valve, and even simulating various short-circuit faults in a simulation system makes it difficult to trigger this protection action. Summary of the Invention

[0005] In view of this, this application provides a method, apparatus and related equipment for testing the over-protection of temporary interlocking of flexible DC valve control, so as to realize the functional testing of the over-protection of temporary interlocking of flexible DC valve control.

[0006] To achieve the above objectives, the first aspect of this application provides a method for testing the over-protection of temporary lockout in flexible direct current valve control, comprising:

[0007] Based on the main loop topology of the flexible DC system simulation model, the set of operating conditions is determined, which includes multiple operating conditions for triggering the flexible DC valve-controlled temporary lockout protection.

[0008] Based on the criteria and settings of the temporary lockout over-protection of the flexible direct valve control, and each working condition in the set of working conditions, multiple consecutive fault working conditions are determined.

[0009] Each of the continuous fault conditions is triggered one by one in the flexible DC system simulation model, and waveform data in the flexible DC system simulation model is obtained.

[0010] Based on the waveform data, determine whether the flexible direct current valve-controlled temporary lockout over-protection responds in accordance with the design principles;

[0011] If the flexible direct current valve-controlled temporary interlocking protection fails to respond according to the design principles, it is determined that the flexible direct current valve-controlled temporary interlocking protection has failed the test.

[0012] Preferably, the process of determining the set of operating conditions based on the main loop topology of the flexible DC system simulation model includes:

[0013] Based on the main circuit topology of the flexible DC system simulation model, multiple fault types are determined for triggering the flexible DC valve-controlled temporary blocking protection. The fault types are used to characterize the faults under different fault phases of the flexible DC system simulation model, and the fault phase is the phase in which the fault occurs.

[0014] Within a preset range, the maximum value of the preset range is used as the initial value, and a decrementing operation is performed on the initial value with a preset step size to obtain multiple voltage values ​​within the preset range.

[0015] For each fault type, each voltage value is used as the voltage of the fault phase immediately after the fault, resulting in multiple fault types with different voltage drop degrees.

[0016] For each voltage drop level, the fault type is as follows:

[0017] In the simulation model of the flexible DC system, a fault of the type matching the voltage drop level is triggered, and it is determined whether the flexible DC valve control has a temporary blocking protection.

[0018] If so, the fault type of the voltage drop is determined as the target fault condition;

[0019] The set of operating conditions consists of various target fault conditions.

[0020] Preferably, the fault types include:

[0021] Phase A grounding, Phase B grounding, Phase C grounding, AB phase-to-phase short circuit, BC phase-to-phase short circuit, CA phase-to-phase short circuit, AB phase grounding, BC phase grounding, CA phase grounding and / or three-phase grounding.

[0022] Preferably, the preset range is 95% to 0% of the original voltage setting of the fault phase; the preset step size is 5% of the original voltage setting of the fault phase.

[0023] Preferably, the process of determining multiple consecutive fault conditions based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, and each condition in the set of operating conditions, includes:

[0024] Based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, the continuous fault parameters for each continuous fault condition are determined.

[0025] For each working condition in the set of working conditions, a continuous fault working condition is constructed based on the working condition and the continuous fault parameters;

[0026] The continuous fault parameters include: the number of faults in a continuous fault condition, the duration of each fault, and the interval between adjacent faults.

[0027] Preferably, the process of determining the continuous fault parameters for each continuous fault condition based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection includes:

[0028] The duration Δts of the i-th fault is constrained by the following equation. i And the time interval Δtis from the i-th fault to the (i+1)-th fault. i :

[0029] ΔTs1≤Δts i ≤1.5×ΔTs1

[0030] ΔTs i ≤Δtis i ≤2.5×ΔTs i

[0031]

[0032] Δts i ≤Δtis i

[0033] Wherein, the action time of the flexible direct current valve-controlled temporary lockout over-protection is m, the number of actions is x, and ΔTs i The time interval between the recovery from the i-th temporary lockout and the subsequent unlocking.

[0034] Preferably, the simulation model of the flexible straight-line system includes:

[0035] The primary circuit model should include at least the MMC converter valve, flexible DC transformer, AC system, starting circuit, and bridge arm reactor of the flexible DC system.

[0036] It should include at least the typical control functions of flexible DC, such as DC power control, DC voltage control, and AC fault ride-through strategy.

[0037] It should include at least the typical protection functions of flexible DC valve-controlled temporary lockout protection and flexible DC valve-controlled temporary lockout over-time protection.

[0038] The second aspect of this application provides a test device for temporary lockout over-protection of flexible direct current valve control, comprising:

[0039] The operating condition determination unit is used to determine the set of operating conditions based on the main loop topology of the flexible DC system simulation model. The set of operating conditions includes multiple operating conditions for triggering the flexible DC valve-controlled temporary lockout protection.

[0040] The event determination unit is used to determine multiple consecutive fault conditions based on the criteria and settings of the flexible direct current valve-controlled temporary blocking over-protection, and each condition in the set of operating conditions.

[0041] The test execution unit is used to trigger each of the continuous fault conditions one by one in the flexible DC system simulation model and to acquire waveform data in the flexible DC system simulation model.

[0042] The data analysis unit is used to determine, based on the waveform data, whether the flexible direct current valve-controlled temporary lockout over-protection responds in accordance with the design principles;

[0043] The result output unit is used to determine if the unit determines that the flexible direct current valve-controlled temporary lockout over-time protection cannot respond according to the design principle, and then determines that the flexible direct current valve-controlled temporary lockout over-time protection has failed the test.

[0044] A third aspect of this application provides a test device for over-protection of temporary lockout of flexible direct current valve control, comprising: a memory and a processor;

[0045] The memory is used to store programs;

[0046] The processor is used to execute the program to implement each step of the above-described method for testing temporary lockout protection of flexible direct current valve control.

[0047] The fourth aspect of this application provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the various steps of the above-described method for testing the temporary lockout over-protection of a flexible direct current valve.

[0048] As described in the above technical solution, this application first determines the set of operating conditions based on the main circuit topology of the flexible DC system simulation model. This set of operating conditions includes multiple conditions used to trigger the flexible DC valve-controlled temporary blocking protection. Then, based on the criteria and settings of the flexible DC valve-controlled temporary blocking over-protection, and each operating condition in the set of operating conditions, multiple consecutive fault operating conditions are determined. These consecutive fault operating conditions are used to trigger the flexible DC valve-controlled temporary blocking over-protection. Next, the consecutive fault operating conditions are triggered one by one in the flexible DC system simulation model, and waveform data is obtained from the model. Finally, based on the waveform data, it is determined whether the flexible DC valve-controlled temporary blocking over-protection responds according to the design principles. If the flexible DC valve-controlled temporary blocking over-protection fails to respond according to the design principles, it is determined that the flexible DC valve-controlled temporary blocking over-protection has failed the test. Understandably, if the flexible DC valve-controlled temporary lockout over-protection responds according to design principles under all operating conditions, then the function of the flexible DC valve-controlled temporary lockout over-protection has passed the test. The technical solution of this application is simple to operate, has good versatility, and strong applicability. It can be implemented on both non-real-time simulation tools and real-time simulation tools, effectively enabling functional testing of the flexible DC valve-controlled temporary lockout over-protection. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the test method for temporary lockout protection of flexible direct current valve control disclosed in the embodiments of this application;

[0051] Figure 2 This is a schematic diagram of a typical topology of a flexible DC back-to-back system disclosed in an embodiment of this application;

[0052] Figure 3 This is a schematic diagram of a typical topology of a high-voltage flexible DC transmission system disclosed in the embodiments of this application;

[0053] Figure 4 This is a schematic diagram of a typical topology of the ultra-high voltage flexible DC transmission system disclosed in the embodiments of this application;

[0054] Figure 5 This is a schematic diagram of the continuous fault simulation logic of the sending-end AC system disclosed in the embodiments of this application;

[0055] Figure 6This is a schematic diagram of the three-phase voltage waveforms on the grid side of the MMC1 converter flexible DC converter disclosed in the embodiments of this application;

[0056] Figure 7 This is a schematic diagram of the positive and negative DC voltage waveforms of the MMC1 converter disclosed in the embodiments of this application;

[0057] Figure 8 This is a schematic diagram of the DC current waveforms of the positive and negative terminals of the MMC1 converter disclosed in the embodiments of this application;

[0058] Figure 9 This is a schematic diagram of the upper arm current waveform of the MMC1 converter disclosed in the embodiments of this application;

[0059] Figure 10 This is a schematic diagram of the lower arm current waveform of the MMC1 converter disclosed in the embodiments of this application;

[0060] Figure 11 This is a schematic diagram of the MMC1 related flag bits disclosed in the embodiments of this application;

[0061] Figure 12 This is a schematic diagram of the continuous fault simulation logic of the receiving-end AC system disclosed in the embodiments of this application;

[0062] Figure 13 The three-phase voltage waveforms on the grid side of the MMC2 converter flexible DC converter disclosed in this application embodiment.

[0063] Figure 14 The DC voltage waveforms of the positive and negative terminals of the MMC2 converter disclosed in this application are shown in the embodiments.

[0064] Figure 15 The DC current waveforms of the positive and negative terminals of the MMC2 converter disclosed in this application are shown in the embodiments.

[0065] Figure 16 The upper arm current waveform of the MMC2 converter disclosed in this application embodiment

[0066] Figure 17 The lower arm current waveform of the MMC2 converter disclosed in this application embodiment

[0067] Figure 18 This is a schematic diagram of the MMC2 related flag bits disclosed in the embodiments of this application;

[0068] Figure 19 This is a schematic diagram of the flexible direct current valve-controlled temporary lockout over-protection test device disclosed in the embodiments of this application;

[0069] Figure 20 This is a schematic diagram of the flexible direct current valve-controlled temporary lockout over-protection test equipment disclosed in the embodiments of this application. Detailed Implementation

[0070] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0071] The following describes the test method for over-protection of temporary interlocking of flexible direct current valve control provided in the embodiments of this application. Please refer to... Figure 1 The method for testing the temporary lockout over-protection of flexible direct current valve control provided in this application embodiment may include the following steps:

[0072] Step S101: Determine the set of operating conditions based on the main loop topology of the flexible DC system simulation model.

[0073] The simulation model of the flexible DC system was built in advance in the simulation tool; the set of operating conditions includes multiple operating conditions that trigger the flexible DC valve-controlled temporary blocking protection. Specifically, the operating condition is a circuit abnormality that can trigger the flexible DC valve-controlled temporary blocking protection, such as phase A grounding, phase B grounding, etc.

[0074] Step S102: Based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, and each working condition in the set of working conditions, determine multiple consecutive fault working conditions.

[0075] The criteria and settings for the over-protection of temporary blocking of flexible DC valve control can include the action time m and the number of actions x. Its physical meaning is that if the number of times temporary blocking occurs continuously within the duration m reaches m times, the over-protection of temporary blocking of flexible DC valve control will be triggered.

[0076] For example, a continuous failure condition can be set to occur x times consecutively within a duration m. Therefore, assuming that the set of conditions contains k conditions, k continuous failure conditions can be constituted according to the aforementioned rules.

[0077] Step S103: Trigger each continuous fault condition one by one in the flexible DC system simulation model and obtain the waveform data in the flexible DC system simulation model.

[0078] It is understandable that the simulation model of the flexible DC system generates corresponding waveform data before triggering a continuous fault condition, and after each fault within a continuous fault condition. Therefore, each continuous fault condition corresponds to a set of waveform data.

[0079] Step S104: Based on the waveform data, determine whether the flexible direct current valve-controlled temporary lockout over-protection responds in accordance with the design principles.

[0080] In step S105, if a situation occurs where the response cannot be carried out according to the design principles, it is determined that the temporary lockout protection of the flexible direct current valve control has failed the test.

[0081] Understandably, in the above tests, for each continuous fault condition in the power system with the most stringent safety requirements, if even one instance occurs where the system fails to respond according to design principles, the flexible DC valve-controlled temporary blocking over-intervention protection is considered to have failed the test. Conversely, if the flexible DC valve-controlled temporary blocking over-intervention protection responds according to design principles for all conditions, then its function is considered to have passed the test.

[0082] In addition, the continuous fault conditions that cause the test to fail, as well as the corresponding waveform data, can be recorded so that the temporary lockout protection of the flexible direct current valve can be analyzed and improved in the future.

[0083] This application first determines a set of operating conditions based on the main circuit topology of the flexible DC system simulation model. This set includes multiple operating conditions used to trigger the flexible DC valve-controlled temporary blocking protection. Then, based on the criteria and settings of the flexible DC valve-controlled temporary blocking over-protection, and each operating condition in the set, multiple consecutive fault operating conditions are determined. These consecutive fault operating conditions are used to trigger the flexible DC valve-controlled temporary blocking over-protection. Next, these consecutive fault operating conditions are triggered one by one in the flexible DC system simulation model, and waveform data is acquired from the model. Finally, based on this waveform data, it is determined whether the flexible DC valve-controlled temporary blocking over-protection responds according to the design principles. If a situation arises where the response does not meet the design principles, the flexible DC valve-controlled temporary blocking over-protection is deemed to have failed the test. The method of this application is simple to operate, has good versatility, and strong applicability. It can be implemented on both non-real-time simulation tools and real-time simulation tools, effectively performing functional testing on the flexible DC valve-controlled temporary blocking over-protection.

[0084] In some embodiments of this application, the simulation model of the flexible vertical transmission system mentioned above may include:

[0085] A1 includes at least the primary circuit model of the flexible DC system MMC converter valve, flexible DC transformer, AC system, starting circuit, and bridge arm reactor.

[0086] A2 includes at least the typical control functions of flexible DC, such as DC power control, DC voltage control, and AC fault ride-through strategy.

[0087] A3 includes at least the typical protection functions of flexible DC valve-controlled temporary lockout protection and flexible DC valve-controlled temporary lockout over-time protection.

[0088] Among them, flexible DC systems at both ends can be divided into flexible DC back-to-back systems, high-voltage flexible DC transmission systems, and ultra-high-voltage flexible DC transmission systems.

[0089] For a flexible vertical back-to-back system, the entire system has a symmetrical monopolar (pseudo-bipolar) structure, and a typical topology diagram is shown below. Figure 2 As shown, each end contains one converter (MMC1, MMC2) and does not involve a grounding electrode. Clamping is achieved through the flexible DC-DC converter valve side.

[0090] For high-voltage flexible DC transmission systems, symmetrical monopole (pseudo-bipolar) or symmetrical bipolar (true bipolar) structures can be adopted. A typical topology diagram under true bipolar is shown below. Figure 3 As shown, it includes two converter stations (MMC1 and MMC2). Each converter station has one MMC converter for both positive and negative poles, and each has a grounding electrode. The two MMC converters are connected by a DC line.

[0091] For ultra-high voltage (UHV) flexible direct current (DC) transmission systems, a symmetrical bipolar (true bipolar) structure can be adopted. Compared to high voltage (HV) flexible DC transmission systems, UHV flexible DC transmission systems use a structure of two MMC converters connected in series for each electrode. A typical topology diagram of an UHV flexible DC transmission system is shown below. Figure 3 As shown, it includes two converter stations (MMC1 and MMC2). The two MMC converter stations are connected by a DC line and are each equipped with a grounding electrode. Each converter station has two MMC converters on both the positive and negative poles.

[0092] In some embodiments of this application, the process of determining the set of operating conditions based on the main loop topology of the flexible DC system simulation model in step S101 may include:

[0093] S1. Based on the main circuit topology of the flexible DC system simulation model, various fault types are determined.

[0094] The fault is used to trigger the flexible DC valve-controlled temporary blocking protection. The fault type is used to characterize the fault situation under different fault phases, and the fault phase is the phase in which the fault occurs. For example, if the fault is a phase A ground fault, then the fault phase is phase A, and the fault type is phase A ground fault; if the fault is an A / B phase short circuit, then the fault phase is phase AB, and the fault type is A / B phase short circuit.

[0095] S2, within a preset range, using the maximum value of the preset range as the initial value, and performing a decrement operation on the initial value with a preset step size, to obtain multiple voltage values ​​within the preset range.

[0096] For example, assuming the faulty phase is phase A, under normal circumstances, the steady-state operating voltage of phase A is U0. The preset range is set to 90% to 0% of U0, and the preset step size is set to 20% of U0. Then, the initial value is 90%U0, and the initial value is decremented by 20% of U0. The resulting voltage values ​​are 90%U0, 70%U0, 50%U0, 30%U0, and 10%U0, respectively.

[0097] S3, for each fault type, uses each voltage value as the voltage of the fault phase at the instant after the fault, to obtain various fault types with different voltage drop degrees.

[0098] For example, suppose there are two fault types: phase A to ground and phase A to phase B short circuit; these voltage values ​​are 90%U0, 70%U0, 50%U0, 30%U0, and 10%U0, respectively. Then, the fault types with different voltage drops can include:

[0099] Phase A grounding with an instantaneous voltage of 90%U0 after a phase A fault; Phase A grounding with an instantaneous voltage of 70%U0 after a phase A fault; Phase A grounding with an instantaneous voltage of 50%U0 after a phase A fault; Phase A grounding with an instantaneous voltage of 30%U0 after a phase A fault; Phase A grounding with an instantaneous voltage of 10%U0 after a phase A fault.

[0100] And the following are examples of AB phase-to-phase short circuits with an instantaneous voltage of 90%U0 after a fault, AB phase-to-phase short circuits with an instantaneous voltage of 70%U0 after a fault, AB phase-to-phase short circuits with an instantaneous voltage of 50%U0 after a fault, AB phase-to-phase short circuits with an instantaneous voltage of 30%U0 after a fault, and AB phase-to-phase short circuits with an instantaneous voltage of 10%U0 after a fault.

[0101] S4, for each fault type of voltage drop:

[0102] In the simulation model of the flexible DC system, a fault of the fault type matching the voltage drop level is triggered, and it is determined whether the flexible DC valve control has a temporary blocking protection.

[0103] If so, the fault type corresponding to the degree of voltage drop is identified as the target fault condition.

[0104] After traversing all fault types, multiple target fault conditions are obtained, and the set of conditions is composed of each target fault condition.

[0105] The preceding paragraph only listed two fault types. In practical applications, power systems have three phases: A, B, and C. Fault types can be arbitrarily combined among these three. Therefore, in some embodiments of this application, the fault types mentioned above may include:

[0106] At least one of the following: A-phase grounding, B-phase grounding, C-phase grounding, AB-phase short circuit, BC-phase short circuit, CA-phase short circuit, AB-phase grounding, BC-phase grounding, CA-phase grounding, and three-phase grounding.

[0107] The preset range mentioned above is set to 90% to 0% of U0, and the preset step size is set to 20% of U0. In practical applications, to improve test accuracy and refine the granularity of the test, the preset range can be increased while the preset step size can be decreased. Based on this, in some embodiments of this application, the preset range mentioned above can be 95% to 0% of the originally set voltage of the fault phase; and the preset step size can be 5% of the originally set voltage of the fault phase.

[0108] The following describes the detailed process of determining the operating condition set using a specific example, based on the above embodiments, specifically for the flexible direct delivery end. Specifically, the process of determining the operating condition set may include:

[0109] S1, build the fault simulation logic for the flexible direct transmission AC system.

[0110] The simulated AC fault type is represented by a 6-bit binary number FLT_TYPE_S. Each bit of this 6-bit binary number, from least significant to most significant, corresponds to A-phase grounding, B-phase grounding, C-phase grounding, AB-phase short circuit, BC-phase short circuit, and CA-phase short circuit, respectively. Different combinations of these 6 bits result in different fault type control words. For example, 000001 indicates A-phase grounding, 000011 indicates AB-phase grounding, 000111 indicates ABC-phase grounding, and so on. Ignoring composite faults, there are a total of 10 fault types (denoted as variable i): A-phase grounding, B-phase grounding, C-phase grounding, AB-phase short circuit, BC-phase short circuit, CA-phase short circuit, AB-phase grounding, BC-phase grounding, CA-phase grounding, and three-phase grounding. The voltage drop of the faulty phase is adjustable, ranging from 95% to 0%, with an adjustment step size of 5%.

[0111] S2, set the initial value of variable i to 1; set the initial value of variable sf to 100; set the initial value of variable k to 0.

[0112] S3, run the simulation model to operate the DC power at its rated power.

[0113] S4, let sf = sf-5, simulate the i-th type of fault in the AC system of the flexible direct transmission end in the simulation model, the fault voltage drops to sf% of the initial value, the fault time is the time interval ΔTs1 from the recovery of the flexible direct transmission end valve control from the first temporary lockout to the unlocking again.

[0114] S5. Observe the response of the flexible DC after the fault. If the valve control at the sending end of the flexible DC is temporarily blocked, record the fault point in the temporary blocking action data set of the sending end valve control S_TB, and at the same time, increment k.

[0115] S6, determine if sf is greater than 0. If sf>0, repeat steps S4 to S5; if sf<0, execute S7.

[0116] S7, let i++, check if i is less than 10. If i≤10, repeat steps S4 to S6; otherwise, end the fault test of the flexible direct-feed AC system and obtain the set of operating conditions S_TB of valve-controlled temporary lockout protection of the flexible direct-feed end, which contains k operating conditions (i.e. specific fault forms).

[0117] The above provides a set of operating conditions that can trigger a single instance of flexible DC valve-controlled temporary lockout protection. The following describes how to determine continuous fault operating conditions in order to further trigger the flexible DC valve-controlled temporary lockout over-time protection.

[0118] In some embodiments of this application, the process of determining multiple consecutive fault conditions in step S102 based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection and each condition in the set of operating conditions may include:

[0119] S1, based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, determine the continuous fault parameters for each continuous fault condition.

[0120] S2, for each working condition in the set of working conditions, construct a continuous fault working condition based on the working condition and the continuous fault parameters.

[0121] The continuous fault parameters include: the number of faults in a continuous fault condition, the duration of each fault, and the interval between adjacent faults.

[0122] In some embodiments of this application, the process of determining the continuous fault parameters for each continuous fault condition based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection in S1 may include:

[0123] The duration Δts of the i-th fault is constrained by the following equation. i And the time interval Δtis from the i-th fault to the (i+1)-th fault. i :

[0124] ΔTs1≤Δts i ≤1.5×ΔTs1

[0125] ΔYs i ≤ΔtiS i ≤2.5×ΔTS i

[0126]

[0127] Δts i ≤Δtis i

[0128] The operating time of the flexible direct current valve-controlled temporary lockout over-protection is m, the number of operations is x, and ΔTs is... i The time interval between the recovery from the i-th temporary lockout and the subsequent unlocking.

[0129] The following describes, with reference to the above embodiments, a specific example of testing the valve-controlled temporary lockout over-protection of the flexible direct feed end under continuous failure conditions. Specifically, the process may include:

[0130] S1, determine the specific parameters for the over-protection of the valve-controlled temporary lockout at the flexible direct delivery end.

[0131] Specifically, the duration of the temporary interlock protection action at the flexible direct-feed end valve is denoted as m, and the number of times is denoted as x. That is, within the time m, the valve control experiences a total of x temporary interlocks, and the valve control trips during the xth temporary interlock, and will not unlock again afterward.

[0132] S2, determine the time interval data between the recovery of the flexible direct-feed end valve control from temporary lockout to unlocking again.

[0133] Specifically, the time interval between the recovery and re-unlocking of the flexible direct-feed valve control from a temporary lockout is denoted as dataset ΔTsx. Corresponding to the number of temporary lockouts, this dataset contains x data points. That is: the time interval between the first temporary lockout recovery and re-unlocking is ΔTs1, the time interval between the second temporary lockout recovery and re-unlocking is ΔTs2, and the time interval between the xth temporary lockout recovery and re-unlocking is ΔTs. x .

[0134] S3, determine the AC fault duration dataset.

[0135] Specifically, the duration of the AC fault is denoted as the dataset Δtsx, where ΔTs1≤Δts i ≤1.5×ΔTs1, that is, the duration of the AC fault is at least the time interval between the first temporary lockout and the second unlocking, and at most 1.5 times that time.

[0136] S4 determines the interval between faults.

[0137] Specifically, the interval between the end of the i-th AC fault and the occurrence of the (i+1)-th AC fault (the interval between the i-th AC faults) is denoted as the dataset Δtisx, where ΔTs i ≤Δtisi ≤2.5×ΔTs i That is, the interval between the end of the i-th AC fault and the occurrence of the (i+1)-th AC fault must be at least the time interval between the recovery from the i-th temporary lockout and the unlocking, and at most 2.5 times that time. Furthermore, Δts must be satisfied. i ≤Δtis i That is, the interval between the end of the i-th AC fault and the occurrence of the (i+1)-th AC fault is not less than the duration of the i-th AC fault.

[0138] In addition, the time variables in S2, S3, and S4 above also need to satisfy:

[0139]

[0140] S5, build a continuous fault simulation logic for the flexible direct transmission AC system.

[0141] For example, the continuous fault simulation logic of the flexible direct-transmission AC system is as follows: Figure 5 As shown. The fault trigger signal is a pulse signal; the fault type is given by a multiplexer. Each fault timing sequence includes one rising-edge monostable multivibrator and one falling-edge monostable multivibrator. The hold time t0 of the rising-edge monostable multivibrator in the first fault timing sequence must be greater than the pulse width of the fault trigger signal (typically one simulation step) to capture the fault trigger signal. The hold time of the rising-edge monostable multivibrator in subsequent fault timing sequences is the time interval between the end of the previous fault and the occurrence of the next fault; the falling-edge monostable multivibrator in the fault timing sequence represents the fault duration. The fault trigger control word for each fault timing sequence is obtained by multiplying the fault timing logic with the fault type. The fault trigger control word for the entire continuous fault sequence is obtained by performing an OR operation on the fault control words of multiple fault timing sequences.

[0142] Specifically, the continuous fault simulation logic is set as follows: the first fault lasts for Δts1, and the second fault occurs again after an interval of Δts1; the second fault lasts for Δts2, and the third fault occurs again after an interval of Δts2; the xth fault lasts for Δts... x .

[0143] S6, set the initial value of variable us to 1 and the initial value of variable vs to 0.

[0144] S7 runs the simulation model, switching the DC power to rated power operating conditions.

[0145] S8 is the us-th consecutive fault in the trigger-sender valve-controlled temporary lockout action data set S_TB.

[0146] S9. Analyze the rationality of the temporary lockout protection action of the sending valve based on the test waveform.

[0147] S10, if the temporary lockout protection action of the flexible direct valve at the sending end exceeds the design principle.

[0148] S11, if the valve-controlled temporary blocking over-protection at the feed end operates correctly or fails to operate correctly, then the test under this condition is valid. Record the fault point in the feed-end valve-controlled temporary blocking over-protection operation condition dataset S_TBM, and simultaneously increment vs++.

[0149] S12, let us++, and determine whether us is greater than k. If us≤k, repeat steps S5 to S9; otherwise, complete the over-protection test of the temporary interlocking of the valve control at the flexible direct delivery end.

[0150] Based on the above method for testing the valve-controlled temporary blocking over-protection of the flexible DC transmission end under continuous fault conditions, the following section presents the test method and test results of a certain flexible DC back-to-back DC transmission end valve-controlled temporary blocking over-protection under a certain operating condition, combined with specific parameters.

[0151] S1. Establish a simulation model of the flexible straight-line system in the simulation tool.

[0152] The established model includes at least the following: primary circuit models of the flexible DC system MMC converter valve, flexible DC transformer, AC system, start-up circuit, and bridge arm reactor; typical flexible DC control functions including DC power control, DC voltage control, and AC fault ride-through strategy; and typical flexible DC protection functions including flexible DC valve-controlled temporary blocking protection and flexible DC valve-controlled temporary blocking over-protection.

[0153] S2, build the fault simulation logic for the flexible direct transmission AC system.

[0154] S3, run the simulation model, and switch the DC operation to HVDC (high-voltage direct current) mode with 1pu rated power operation condition.

[0155] S4 triggers a three-phase ground fault at the flexible direct transmission end, causing the valve control at the flexible direct transmission end to temporarily lock out.

[0156] S5, verify that the over-protection time for the temporary lockout of the flexible direct delivery valve is 1s, and the number of times is set to 4; verify that the time interval between the first temporary lockout recovery and the second unlocking is 15ms, the time interval between the second temporary lockout recovery and the third unlocking is 300ms.

[0157] S6. Based on the relevant set values ​​of the temporary lockout of the valve control at the flexible direct transmission end, the continuous fault simulation logic of the AC system at the flexible direct transmission end is built in the model.

[0158] Specifically, the first fault lasts for 20ms, and the second fault occurs after a 20ms interval; the second fault lasts for 20ms, and the third fault occurs after a 20ms interval; the third fault lasts for 20ms, and the fourth fault occurs after a 350ms interval, and the fourth fault lasts for 20ms.

[0159] S7, run the simulation model, and operate the flexible DC system to the HVDC mode 1pu rated power operating condition.

[0160] S8 triggers a three-phase grounding continuous fault at the flexible direct transmission end, causing the valve-controlled temporary blocking protection at the flexible direct transmission end to operate beyond the specified number of times.

[0161] For example, Figures 6 to 11 The waveform diagram of a three-phase ground fault occurring in the AC system at the flexible direct-transmission end during S8 HVDC mode 1pu rated power operation is given. Figure 6 The waveforms of the three-phase voltage on the grid side of the MMC1 converter flexible DC transformer are shown. Figure 7 The waveforms are the positive and negative DC voltages of the MMC1 converter. Figure 8 The waveforms of the positive and negative DC currents of the MMC1 converter are shown. Figure 9 The waveform of the upper arm current of the MMC1 converter is shown. Figure 10 The waveform of the lower arm current of the MMC1 converter is shown. Figure 11 The flags are: MMC1 undervoltage ride-through enable flag, MMC1 valve-controlled temporary lockout protection action flag, MMC1 valve-controlled temporary lockout over-protection action flag, MMC1 valve-controlled trip request flag, and MMC1 unlock status flag.

[0162] The following describes the detailed process of determining the set of operating conditions using a specific example, based on the above embodiments, specifically for the flexible DC receiving end. Specifically, the process of determining the set of operating conditions may include:

[0163] S1, build the fault simulation logic for the flexible direct transmission AC system.

[0164] The simulated AC fault type is represented by a 6-bit binary number FLT_TYPE_R. Each bit of this 6-bit number, from least significant to most significant, corresponds to A-phase grounding, B-phase grounding, C-phase grounding, AB-phase short circuit, BC-phase short circuit, and CA-phase short circuit, respectively. Different combinations of these 6 bits result in different fault type control words. For example, 000001 indicates A-phase grounding, 000011 indicates AB-phase faulting, 000111 indicates ABC-phase three-phase grounding, and so on. Ignoring composite faults, there are a total of 10 fault types (denoted as variable i): A-phase grounding, B-phase grounding, C-phase grounding, AB-phase short circuit, BC-phase short circuit, CA-phase short circuit, AB-phase grounding, BC-phase grounding, CA-phase grounding, and three-phase grounding. The voltage drop of the faulty phase is adjustable, ranging from 95% to 0%, with an adjustment step size of 5%.

[0165] S2, set the initial value of variable j to 1. Set the initial value of variable rf to 100; set the initial value of variable l to 0.

[0166] S3, run the simulation model to operate the DC power at its rated power.

[0167] S4, let rf = rf-5, simulate a type j fault in the AC system at the flexible DC receiving end in the simulation model, the fault voltage drops to rf% of the initial value, the fault time is the time interval ΔTr1 from the recovery of the flexible DC receiving end valve control from the first temporary lockout to the unlocking again.

[0168] S5. Observe the response of the flexible DC after the fault. If the valve control at the receiving end of the flexible DC is temporarily blocked, record the fault point in the temporary blocking action data set R_TB of the receiving end valve control, and increment l.

[0169] S6, determine if rf is greater than 0. If rf > 0, repeat steps S4 to S5; if rf ≤ 0, execute S7.

[0170] S7, let j++, and determine if j is less than 10. If j≤10, repeat steps S4 to S6; otherwise, end the fault test of the flexible DC receiving end AC system and obtain the set of operating conditions R_TB of valve-controlled temporary blocking protection at the flexible DC receiving end, which includes l operating conditions (i.e., specific fault forms).

[0171] The following describes, with reference to the above embodiments, a specific example of testing the valve-controlled temporary blocking over-protection of the flexible DC receiving end under continuous fault conditions. Specifically, the process may include:

[0172] S1, determine the specific parameters for the over-protection of the flexible DC receiving end valve-controlled temporary lockout.

[0173] Specifically, the duration of the temporary interlocking protection operation at the flexible DC receiving end valve is denoted as n, and the number of operations is set to y. That is, within the time period n, the valve control will experience a total of y temporary interlocking events. The valve control will trip during the yth temporary interlocking event and will not unlock again afterward.

[0174] S2, determine the time interval dataset from when the flexible DC receiving end valve recovers from temporary locking to when it unlocks again.

[0175] Specifically, the time interval between the recovery and re-unlocking of the flexible DC receiving-end valve control from temporary locking is denoted as the dataset ΔTry. Corresponding to the number of temporary locking events, this dataset contains y data points. That is: the time interval between the first temporary locking recovery and re-unlocking is ΔTr1, the time interval between the second temporary locking recovery and re-unlocking is ΔTr2, and the time interval between the yth temporary locking recovery and re-unlocking is ΔTr... y .

[0176] S3, determine the AC fault duration dataset.

[0177] Specifically, the duration of the AC fault is denoted as the dataset Δtry, where ΔTr1 ≤ Δtr i ≤ 1.5×ΔTr1, that is, the duration of the AC fault is at least the time interval between the first temporary lockout recovery and the second unlocking, and at most 1.5 times that time.

[0178] S4 determines the interval between faults.

[0179] Specifically, the interval between the end of the i-th AC fault and the occurrence of the (i+1)-th AC fault (the interval between the i-th AC faults) is denoted as the dataset Δtiry, where ΔTr i ≤Δtir i ≤2.5×ΔTr i That is, the interval between the end of the i-th AC fault and the occurrence of the (i+1)-th AC fault is at least the time interval between the recovery from the i-th temporary lockout and the unlocking, and at most 2.5 times that time. Furthermore, Δtr must be satisfied. i ≤Δtir i That is, the interval between the end of the i-th AC fault and the occurrence of the (i+1)-th AC fault is not less than the duration of the i-th AC fault.

[0180] In addition, the time variables in S2, S3, and S4 above also need to satisfy:

[0181]

[0182] S5, build a continuous fault simulation logic for the flexible DC receiving-end AC system.

[0183] For example, the continuous fault simulation logic of the flexible DC receiving end AC system is as follows: Figure 12 As shown. The AC fault simulation logic for the sending and receiving ends is similar, except that the fault trigger signal source, fault duration, fault time interval, and fault type are set according to the actual needs of each end. Therefore, for a detailed introduction to this continuous fault simulation logic, please refer to the above description of the continuous fault simulation logic for the flexible direct transmission AC system.

[0184] Specifically, the continuous fault simulation logic is set as follows: the first fault lasts for Δtr1, and the second fault occurs after an interval of Δtr1; the second fault lasts for Δtr2, and the third fault occurs after an interval of Δtr2; the y-th fault lasts for Δtr... y .

[0185] S6, set the initial value of variable ur to 1 and the initial value of variable vr to 0.

[0186] S7 runs the simulation model, switching the DC power to rated power operating conditions.

[0187] S8 triggers the ur-th consecutive fault in the receiving-end valve-controlled temporary lockout action data set R_TB;

[0188] S9. Analyze the rationality of the over-protection action of the temporary lockout of the valve controlled by the receiving end based on the test waveform.

[0189] S10, if the temporary lockout protection action of the flexible direct valve control exceeds the design principle.

[0190] S11. If the temporary interlocking protection of the flexible DC receiving end valve operates correctly or fails to operate correctly, then the test under this condition is valid. Record the fault point in the receiving end valve-controlled temporary interlocking protection operation condition dataset R_TBM, and simultaneously increment vr.

[0191] S12, let ur++, determine if ur is greater than l. If ur≤l, repeat steps S5 to S9; if ur>l; otherwise, complete the over-protection test of the temporary interlocking of the flexible DC receiving end valve.

[0192] Based on the above method for testing the valve-controlled temporary blocking over-protection of the flexible DC transmission end under continuous fault conditions, the following section presents the test method and test results of a certain flexible DC back-to-back DC receiving end valve-controlled temporary blocking over-protection under a certain operating condition, combined with specific parameters.

[0193] S1. Establish a simulation model of the flexible straight-line system in the simulation tool.

[0194] The established model includes at least the following: primary circuit models of the flexible DC system MMC converter valve, flexible DC transformer, AC system, start-up circuit, and bridge arm reactor; typical flexible DC control functions including DC power control, DC voltage control, and AC fault ride-through strategy; and typical flexible DC protection functions including flexible DC valve-controlled temporary blocking protection and flexible DC valve-controlled temporary blocking over-protection.

[0195] S2, build the fault simulation logic of the flexible DC receiving end AC system.

[0196] S3, run the simulation model to switch the DC operation to HVDC mode 1pu rated power operation condition.

[0197] S4 triggers a two-phase ground fault at the flexible DC receiving end, causing a temporary valve-controlled interlock at the flexible DC receiving end.

[0198] S5, verify that the over-protection time for the temporary lockout at the flexible DC receiving end valve is 1s, and the number of times is set to 4; verify that the time interval between the first temporary lockout recovery and the second unlocking is 15ms, the time interval between the second temporary lockout recovery and the third unlocking is 300ms.

[0199] S6. Based on the relevant set values ​​of the temporary blocking of the flexible DC receiving end valve control, the continuous fault simulation logic of the flexible DC receiving end AC system is built in the model.

[0200] Specifically, the first fault lasts for 20ms, and the second fault occurs after a 20ms interval; the second fault lasts for 20ms, and the third fault occurs after a 20ms interval; the third fault lasts for 20ms, and the fourth fault occurs after a 700ms interval, and the fourth fault lasts for 20ms.

[0201] S7, run the simulation model, and operate the flexible DC system to the HVDC mode 1pu rated power operating condition.

[0202] S8 triggers a continuous ground fault between phases A and B at the flexible DC receiving end, causing the valve-controlled temporary blocking protection at the flexible DC receiving end to operate after the first fault.

[0203] For example, Figures 13-18 The waveform diagram is given for a two-phase ground fault (AB) in the AC system at the flexible DC receiving end during S8 HVDC mode 1pu rated power operation. Figure 13 The waveforms of the three-phase voltage on the grid side of the MMC2 converter flexible DC transformer are shown. Figure 14 Figure 15 shows the DC voltage waveforms at the positive and negative terminals of the MMC2 converter, and Figure 16 shows the DC current waveforms at the positive and negative terminals of the MMC2 converter. Figure 16 The waveform of the upper arm current of the MMC2 converter is shown. Figure 17 The waveform of the lower arm current of the MMC2 converter is shown. Figure 18 The flags are: MMC2 undervoltage ride-through enable flag, MMC2 valve-controlled temporary lockout protection action flag, MMC2 valve-controlled temporary lockout over-protection action flag, MMC2 valve-controlled trip request flag, and MMC2 unlock status flag.

[0204] The following describes the flexible DC valve-controlled temporary interlocking over-protection test device provided in the embodiments of this application. The flexible DC valve-controlled temporary interlocking over-protection test device described below can be referred to in correspondence with the flexible DC valve-controlled temporary interlocking over-protection test method described above.

[0205] Please see Figure 19 The flexible direct current valve-controlled temporary lockout over-protection test device provided in this application embodiment may include:

[0206] Operating condition determination unit 21 is used to determine the set of operating conditions based on the main loop topology of the flexible DC system simulation model. The set of operating conditions includes multiple operating conditions for triggering the flexible DC valve-controlled temporary lockout protection.

[0207] Event determination unit 22 is used to determine multiple consecutive fault conditions based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, and each condition in the set of operating conditions.

[0208] Test execution unit 23 is used to trigger each of the continuous fault conditions in the flexible DC system simulation model one by one, and to acquire waveform data in the flexible DC system simulation model.

[0209] Data analysis unit 24 is used to determine, based on the waveform data, whether the flexible direct current valve-controlled temporary lockout over-protection responds in accordance with the design principles;

[0210] The result output unit 25 is used to determine if the unit determines that the flexible direct current valve-controlled temporary lockout over-time protection cannot respond according to the design principle, and then determines that the flexible direct current valve-controlled temporary lockout over-time protection has failed the test.

[0211] In some embodiments of this application, the process by which the operating condition determination unit 21 determines the set of operating conditions based on the main loop topology of the flexible DC system simulation model may include:

[0212] Based on the main circuit topology of the flexible DC system simulation model, multiple fault types are determined for triggering the flexible DC valve-controlled temporary blocking protection. The fault types are used to characterize the faults under different fault phases of the flexible DC system simulation model, and the fault phase is the phase in which the fault occurs.

[0213] Within a preset range, the maximum value of the preset range is used as the initial value, and a decrementing operation is performed on the initial value with a preset step size to obtain multiple voltage values ​​within the preset range.

[0214] For each fault type, each voltage value is used as the voltage of the fault phase immediately after the fault, resulting in multiple fault types with different voltage drop degrees.

[0215] For each voltage drop level, the fault type is as follows:

[0216] In the simulation model of the flexible DC system, a fault of the type matching the voltage drop level is triggered, and it is determined whether the flexible DC valve control has a temporary blocking protection.

[0217] If so, the fault type of the voltage drop is determined as the target fault condition;

[0218] The set of operating conditions consists of various target fault conditions.

[0219] In some embodiments of this application, the flexible vertical transmission system simulation model may include:

[0220] The primary circuit model should include at least the MMC converter valve, flexible DC transformer, AC system, starting circuit, and bridge arm reactor of the flexible DC system.

[0221] It should include at least the typical control functions of flexible DC, such as DC power control, DC voltage control, and AC fault ride-through strategy.

[0222] It should include at least the typical protection functions of flexible DC valve-controlled temporary lockout protection and flexible DC valve-controlled temporary lockout over-time protection.

[0223] In some embodiments of this application, the fault type may include:

[0224] Phase A grounding, Phase B grounding, Phase C grounding, AB phase-to-phase short circuit, BC phase-to-phase short circuit, CA phase-to-phase short circuit, AB phase grounding, BC phase grounding, CA phase grounding and / or three-phase grounding.

[0225] In some embodiments of this application, the preset range is 95% to 0% of the original voltage set for the fault phase; the preset step size is 5% of the original voltage set for the fault phase.

[0226] In some embodiments of this application, the process by which the event determination unit 22 determines multiple consecutive fault conditions based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, and each condition in the set of operating conditions, may include:

[0227] Based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, the continuous fault parameters for each continuous fault condition are determined.

[0228] For each working condition in the set of working conditions, a continuous fault working condition is constructed based on the working condition and the continuous fault parameters;

[0229] The continuous fault parameters include: the number of faults in a continuous fault condition, the duration of each fault, and the interval between adjacent faults.

[0230] In some embodiments of this application, the process by which the event determination unit 22 determines the continuous fault parameters for each continuous fault condition based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection includes:

[0231] The duration Δts of the i-th fault is constrained by the following equation. i And the time interval Δtis from the i-th fault to the (i+1)-th fault. i :

[0232] ΔTs1≤Δts i ≤1.5×ΔTs1

[0233] ΔTs i ≤Δtis i ≤2.5×ΔTs i

[0234]

[0235] Δts i ≤Δtis i

[0236] Wherein, the action time of the flexible direct current valve-controlled temporary lockout over-protection is m, the number of actions is x, and ΔTs i The time interval between the recovery from the i-th temporary lockout and the subsequent unlocking.

[0237] The flexible DC valve-controlled temporary lockout over-protection test device provided in this application embodiment can be applied to flexible DC valve-controlled temporary lockout over-protection test equipment, such as computers. Optionally, Figure 20 The hardware structure block diagram of the test equipment for temporary interlocking protection of flexible direct current valve control is shown. (Refer to...) Figure 20 The hardware structure of the flexible direct current valve-controlled temporary lockout over-protection test equipment may include: at least one processor 31, at least one communication interface 32, at least one memory 33 and at least one communication bus 34.

[0238] In this embodiment, the number of processor 31, communication interface 32, memory 33 and communication bus 34 is at least one, and processor 31, communication interface 32 and memory 33 communicate with each other through communication bus 34;

[0239] The processor 31 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0240] The memory 33 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device;

[0241] The memory 33 stores a program, and the processor 31 can call the program stored in the memory 33. The program is used for:

[0242] Based on the main loop topology of the flexible DC system simulation model, the set of operating conditions is determined, which includes multiple operating conditions for triggering the flexible DC valve-controlled temporary lockout protection.

[0243] Based on the criteria and settings of the temporary lockout over-protection of the flexible direct valve control, and each working condition in the set of working conditions, multiple consecutive fault working conditions are determined.

[0244] Each of the continuous fault conditions is triggered one by one in the flexible DC system simulation model, and waveform data in the flexible DC system simulation model is obtained.

[0245] Based on the waveform data, determine whether the flexible direct current valve-controlled temporary lockout over-protection responds in accordance with the design principles;

[0246] If the flexible direct current valve-controlled temporary interlocking protection fails to respond according to the design principles, it is determined that the flexible direct current valve-controlled temporary interlocking protection has failed the test.

[0247] Optionally, the refined and extended functions of the program can be found in the description above.

[0248] This application embodiment also provides a storage medium that can store a program suitable for execution by a processor, the program being used for:

[0249] Based on the main loop topology of the flexible DC system simulation model, the set of operating conditions is determined, which includes multiple operating conditions for triggering the flexible DC valve-controlled temporary lockout protection.

[0250] Based on the criteria and settings of the temporary lockout over-protection of the flexible direct valve control, and each working condition in the set of working conditions, multiple consecutive fault working conditions are determined.

[0251] Each of the continuous fault conditions is triggered one by one in the flexible DC system simulation model, and waveform data in the flexible DC system simulation model is obtained.

[0252] Based on the waveform data, determine whether the flexible direct current valve-controlled temporary lockout over-protection responds in accordance with the design principles;

[0253] If the flexible direct current valve-controlled temporary interlocking protection fails to respond according to the design principles, it is determined that the flexible direct current valve-controlled temporary interlocking protection has failed the test.

[0254] Optionally, the refined and extended functions of the program can be found in the description above.

[0255] In summary:

[0256] This application first determines the set of operating conditions based on the main circuit topology of the flexible DC system simulation model. This set includes multiple operating conditions used to trigger the flexible DC valve-controlled temporary blocking protection. Then, based on the criteria and settings of the flexible DC valve-controlled temporary blocking over-protection, and each operating condition in the set, multiple consecutive fault operating conditions are determined. These consecutive fault operating conditions are used to trigger the flexible DC valve-controlled temporary blocking over-protection. Next, these consecutive fault operating conditions are triggered one by one in the flexible DC system simulation model, and waveform data is acquired from the simulation model. Finally, based on this waveform data, it is determined whether the flexible DC valve-controlled temporary blocking over-protection responds according to the design principles. If a situation arises where the response does not meet the design principles, the flexible DC valve-controlled temporary blocking over-protection is deemed to have failed the test. This application has good compatibility: it can be implemented on both non-real-time simulation tools (such as PSCAD / EMTDC, MATLAB / SIMULINK) and real-time simulation tools (such as RTDS, RTLAB, Hypersim), effectively performing functional testing on the valve-controlled temporary blocking over-protection of flexible DC transmission systems. It also has strong applicability: it can test the valve-controlled temporary blocking over-protection function of different technical routes at the sending and receiving ends of flexible DC back-to-back systems, high-voltage flexible DC transmission systems, and ultra-high-voltage flexible DC transmission systems. The implementation process is simple: no modification to the control and protection program is required; testing can be completed simply by building a simple test logic in the simulation tool. Finally, it has good completeness: it can verify the valve-controlled temporary blocking over-protection function for valve-controlled temporary blocking conditions caused by different AC fault types.

[0257] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0258] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0259] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A test method for temporary lockout protection exceeding the limit under flexible direct current valve control, characterized in that, include: Based on the main loop topology of the flexible DC system simulation model, the set of operating conditions is determined, which includes multiple operating conditions for triggering the flexible DC valve-controlled temporary lockout protection. Based on the criteria and settings of the temporary lockout over-protection of the flexible direct valve control, and each working condition in the set of working conditions, multiple consecutive fault working conditions are determined. Each of the continuous fault conditions is triggered one by one in the flexible DC system simulation model, and waveform data in the flexible DC system simulation model is obtained. Based on the waveform data, determine whether the flexible direct current valve-controlled temporary lockout over-protection responds in accordance with the design principles; If the flexible direct current valve-controlled temporary interlocking protection fails to respond according to the design principles, it is determined that the flexible direct current valve-controlled temporary interlocking protection has failed the test.

2. The method according to claim 1, characterized in that, The process of determining the set of operating conditions based on the main loop topology of the flexible DC system simulation model includes: Based on the main circuit topology of the flexible DC system simulation model, multiple fault types for triggering the flexible DC valve-controlled temporary blocking protection are determined, including fault conditions under different fault phases; Within a preset range, the maximum value of the preset range is used as the initial value, and a decrementing operation is performed on the initial value with a preset step size to obtain multiple voltage values ​​within the preset range. For each fault type, each voltage value is used as the voltage of the fault phase immediately after the fault, resulting in multiple fault types with different voltage drop degrees. For each voltage drop level, the fault type is as follows: In the simulation model of the flexible DC system, a fault of the type matching the voltage drop level is triggered, and it is determined whether the flexible DC valve control has a temporary blocking protection. If so, the fault type of the voltage drop is determined as the target fault condition; The set of operating conditions consists of various target fault conditions.

3. The method according to claim 2, characterized in that, The fault types include: Phase A grounding, Phase B grounding, Phase C grounding, AB phase-to-phase short circuit, BC phase-to-phase short circuit, CA phase-to-phase short circuit, AB phase grounding, BC phase grounding, CA phase grounding and / or three-phase grounding.

4. The method according to claim 3, characterized in that The preset range is 95% to 0% of the steady-state operating voltage of the fault phase; the preset step size is 5% of the steady-state operating voltage of the fault phase.

5. The method according to claim 1, characterized in that, The process of determining multiple consecutive fault conditions based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, and each condition in the set of operating conditions, includes: Based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection, the continuous fault parameters for each continuous fault condition are determined. For each working condition in the set of working conditions, a continuous fault working condition is constructed based on the working condition and the continuous fault parameters; The continuous fault parameters include: the number of faults in a continuous fault condition, the duration of each fault, and the interval between adjacent faults.

6. The method according to claim 5, characterized in that, The process of determining the continuous fault parameters for each continuous fault condition based on the criteria and settings of the flexible direct current valve-controlled temporary lockout over-protection includes: The duration Δts of the i-th fault is constrained by the following equation. i And the time interval Δtis from the end of the i-th fault to the start of the (i+1)-th fault. i : ΔTS1≤Δts i ≤1.5×ΔTS1 ΔTs i ≤Δtis i ≤2.5×ΔTs i Δts i ≤Δtis i Wherein, the action time of the flexible direct current valve-controlled temporary lockout over-protection is m, the number of actions is x, and ΔTs i The time interval between the recovery from the i-th temporary lockout and the subsequent unlocking.

7. The method according to claim 1, characterized in that, The simulation model of the flexible straight-line system includes: The primary circuit model should include at least the MMC converter valve, flexible DC transformer, AC system, starting circuit, and bridge arm reactor of the flexible DC system. It should include at least the typical control functions of flexible DC, such as DC power control, DC voltage control, and AC fault ride-through strategy. It should include at least the typical protection functions of flexible DC valve-controlled temporary lockout protection and flexible DC valve-controlled temporary lockout over-time protection.

8. A test device for temporary lockout protection of flexible direct current valve control, characterized in that, include: The operating condition determination unit is used to determine the set of operating conditions based on the main loop topology of the flexible DC system simulation model. The set of operating conditions includes multiple operating conditions for triggering the flexible DC valve-controlled temporary lockout protection. The event determination unit is used to determine multiple consecutive fault conditions based on the criteria and settings of the flexible direct current valve-controlled temporary blocking over-protection, and each condition in the set of operating conditions. The test execution unit is used to trigger each of the continuous fault conditions one by one in the flexible DC system simulation model and to acquire waveform data in the flexible DC system simulation model. The data analysis unit is used to determine, based on the waveform data, whether the flexible direct current valve-controlled temporary lockout over-protection responds in accordance with the design principles; The result output unit is used to determine if the unit determines that the flexible direct current valve-controlled temporary lockout over-time protection cannot respond according to the design principle, and then determines that the flexible direct current valve-controlled temporary lockout over-time protection has failed the test.

9. A test device for temporary lockout protection of flexible direct current valve control, characterized in that, include: Memory and processor; The memory is used to store programs; The processor is used to execute the program to implement each step of the test method for temporary lockout protection of flexible direct current valve control as described in any one of claims 1 to 7.

10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements each step of the test method for temporary lockout protection of flexible direct current valve control as described in any one of claims 1 to 7.

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