Method and device for monitoring short-circuit fault in DC voltage area of converter valve test circuit

Abstract

The present invention discloses a method and device for monitoring short-circuit faults in the DC voltage region of a converter valve test circuit. The method comprises: initializing a pause control variable BL of a protection function block to a protection function pause state; collecting voltages at each series port and pole line capacitor port of the converter valve test circuit; determining, based on the voltages at each series port and pole line capacitor port, an instantaneous value of the monitored variable and a maximum value of the monitored variable within a preset time; and monitoring the converter valve test circuit for short-circuit faults in the DC voltage region based on the trip logic state of the protection function block, the instantaneous value of the monitored variable, and the maximum value of the monitored variable within a preset time. The present invention can monitor short-circuit faults in the DC voltage region of the converter valve test circuit, ensuring safe and reliable operation of the test system.

Description

Technical Field

[0001] The present invention relates to the field of converter valve test circuits, and in particular to a method and device for monitoring a DC voltage area short-circuit fault in a converter valve test circuit. Background Art

[0002] This section is intended to provide a background or context to the embodiments of the invention that are recited in the claims. No statement herein is admitted to be prior art by virtue of its inclusion in this section.

[0003] With the rise of DC transmission, a functional test circuit for converter valve assemblies has long been available. This test power supply scheme consists of a set of 6P bridge voltage sources and a set of 6P bridge current sources. The test assembly replaces a portion of the module in one arm of the current source. The voltage source then controls the test assembly through devices such as isolation valves to increase the synthesized synchronous voltage, thereby meeting the test current and voltage parameter requirements for the test assembly. The DC pole lines of a DC transmission system are characterized by high current and high voltage, requiring a variety of regional protection configurations. Common DC pole line protections include traveling wave protection, DC undervoltage protection, and DC line differential protection.

[0004] This synthetic circuit is different from the DC transmission system. The synthetic circuit has been systematically studied and equipped with appropriate measurement points and protection functions. When some faults occur in the DC voltage synthesis area, it mainly relies on voltage characteristics for monitoring and protection. Voltage source charging overvoltage protection and test valve undervoltage protection are often configured to monitor faults in the area.

[0005] However, as the voltage and current of individual components increase, the associated integrated circuits, both newly built and renovated, also face challenges in increasing capacity and power quality. To accommodate product testing across different voltage ranges while also optimizing power quality, a power supply solution has emerged that uses 6P bridges for current sources in parallel and 6P bridges for voltage sources in series.

[0006] The voltage source can be used by connecting two or more lower-capacity 6P bridge groups in series, or by short-circuiting only one group of 6P bridges. Without adding a large number of measuring devices and protection function units, it can flexibly meet the voltage requirements of valve assemblies with more voltage levels, and can carry out various operation tests safely and smoothly. However, the protection measures in the supporting voltage source area need to be adjusted.

[0007] Under the special positioning of the synthetic loop test system, the protection cannot be malfunctioned or refused to operate during the system's startup, operation, shutdown, and testing processes, and can also perform sensitive and rapid protection actions when a fault occurs. Therefore, in response to different test operation modes and the level of test parameters, certain special designs are required for some protection functions, protection input data processing, protection function activation and deactivation conditions, etc.

[0008] Regarding abnormal DC power supply voltage, this article focuses on voltage drops caused by short circuits. This article briefly describes several scenarios in which protection configurations and implementations are implemented for voltage drops caused by short circuits in the DC power supply voltage region.

[0009] In a DC transmission system, DC overcurrent protection, traveling wave protection, and DC undervoltage protection are implemented between the valve outlet and the DC line to monitor short-circuit faults that could cause voltage drops in the DC power supply area. The undervoltage protection employed here is a fixed-limit protection measure, applicable to systems operating at rated voltage, with a certain percentage of reduced voltage allowed.

[0010] In the converter valve assembly functional test circuit, the test voltage and current of the test product are synthesized by different 6P bridges. The short-circuit capacity of the voltage source 6P bridge port is not large, nor does it generate excessive short-circuit current. The DC voltage region contains numerous devices, and short-circuit currents vary significantly at different locations. Therefore, no current measurement points are designed at the DC power supply voltage source port or pole line. In this synthetic test circuit using a single 6P bridge voltage source, short-circuit faults in the DC power supply region after the 6P bridge port cause voltage drops. Undervoltage protection of the test product valve is primarily used. However, the DC voltage region between the 6P bridge DC voltage port and the test product contains capacitors, inductors, and isolation valves. The test product voltage measurement point is not a continuous DC voltage, but rather has a 20ms periodic characteristic in different tests. Furthermore, to test products of different voltage levels, no rated operating voltage is available. Therefore, monitoring for short-circuit faults requires detecting a voltage drop exceeding a certain percentage within a 20ms period, and maintaining this voltage drop for more than 20ms.

[0011] In existing converter valve assembly functional test circuit upgrades, some use two or more 6P bridges in series as the voltage source. In addition to the existing test valve undervoltage protection, some have proposed using voltage source differential pressure protection to monitor the DC voltage supply area. This differential pressure protection scheme uses a fixed difference or ratio between the voltage at the 6P bridge port and the voltage at the test valve port.

[0012] However, in practice, the voltage difference between the power supply voltage outlet and the test valve port of the powered equipment is not proportional. Due to the influence of controllable devices such as isolation valves in the circuit, differential pressure protection between the two points is not easy to implement. Therefore, this function is generally disabled during system operation. The actual system mainly uses the test valve undervoltage protection and AC transformer overcurrent protection to monitor possible short-circuit faults in this area.

[0013] Undervoltage protection, commonly used in DC transmission systems, is a fixed-limit protection measure suitable for systems operating at rated voltage, with a certain percentage of reduced voltage allowed. However, in this test circuit system, the operating voltage is not constant. When operating at a lower voltage, even if the fault voltage stress does not damage the equipment, the corresponding system protection measures may not yet meet the required conditions for operation, causing the protection to fail to operate, resulting in a failure to effectively shut down the system in a timely manner and alerting the test personnel to the system fault. In this synthetic test circuit system with a single 6P bridge voltage source, the undervoltage protection of the test object is used as the power supply monitoring device for the voltage source system. Considering that when synthesizing the test object voltage, the voltage source branch under the controlled operating conditions of the isolation valve does not produce a continuous voltage parameter, requiring periodic sampling. The maximum value of the previous cycle is used as 1p.u. The maximum value of the current cycle is determined to determine whether it has dropped by more than a certain percentage and whether the drop persists into the next cycle or for a certain period of time. For some short-circuit fault phenomena in the voltage source area, this method takes a long time to judge. Before starting the isolation valve and when conducting tests on items such as short-circuit current, it is necessary to temporarily exit the undervoltage protection of the test product, which makes the voltage source lose certain protection functions.

[0014] With the increasing number of such systems in recent years, undisclosed technical solutions may exist. The following similar solutions may exist: A converter valve synthetic test circuit system with a single 6P bridge voltage source adds a DC undervoltage protection function to monitor voltage at the external end of the DC reactor at the 6P bridge port. This, combined with the test product undervoltage protection, can monitor most short-circuit faults in the DC voltage source area. However, due to the different test products requiring different supply voltages, the DC undervoltage protection setting must be modified based on the test voltage. Furthermore, when the system is upgraded and modified, the single 6P bridge voltage source is replaced with two 6P bridges connected in series. The voltage source's constant voltage closed-loop control and protection utilize sampling points outside the reactor, with a non-full voltage output. If one 6P bridge port shorts to ground, the other 6P bridge port may raise the voltage. However, due to the influence of the DC reactor and capacitor, the voltage at the monitoring point will not experience a significant and sustained drop, causing the protection function to fail to operate. If we refer to the low-voltage protection of adding two 6P bridge ports to the DC transmission system, the protection function configuration will increase significantly, and depending on the operating mode and test operating parameters, the activation and deactivation of the protection function and the setting of the set value will require other information besides the PT.

[0015] For converter valve assembly synthetic test circuit systems using two 6P bridges connected in series to form a voltage source, one case proposed adding voltage source differential pressure protection to monitor the DC voltage supply area (using a fixed or proportional difference between the voltage at the port of the series 6P bridge and the voltage at the port of the test product) in addition to the existing test valve undervoltage protection, to detect short-circuit faults in the DC voltage area. However, this method is difficult to implement because controlled equipment such as isolation valves are located in the middle, and the monitored voltages are not measured at two measuring points with a proportional pressure difference. This makes it less suitable for the DC voltage area of the system (it is known that this function, which was set up in the project at the time, has been disabled and not put into use). Even if the characteristic of controlling the isolation valve to periodically open and synthesize the test product voltage is utilized, and a strategy is adopted to perform periodic parameter processing and calculations at the two points, the monitoring function requirements can be met, but the problem of needing to disable protection before activating the isolation valve and during test items such as short-circuit current still exists.

[0016] Therefore, there is an urgent need for a DC voltage area short-circuit fault monitoring solution for a converter valve test circuit that can overcome the above problems. Summary of the Invention

[0017] An embodiment of the present invention provides a method for monitoring a DC voltage region short-circuit fault in a converter valve test circuit, for monitoring a DC voltage region short-circuit fault in the converter valve test circuit to ensure safe and reliable operation of the test system. The method includes:

[0018] Initialize the pause control amount BL of the protection function block to the protection function pause state;

[0019] Collect the voltage of each series port and pole line capacitor port of the converter valve test circuit;

[0020] Determine the instantaneous value of the monitored quantity and the maximum value of the monitored quantity within a preset time according to the voltages of the series ports and the voltage of the polar line capacitor port;

[0021] According to the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within the preset time, the DC voltage area short circuit fault monitoring of the converter valve test circuit is carried out.

[0022] An embodiment of the present invention provides a device for monitoring a DC voltage region short-circuit fault in a converter valve test circuit, for monitoring a DC voltage region short-circuit fault in the converter valve test circuit to ensure safe and reliable operation of the test system. The device includes:

[0023] A control quantity initialization module is used to initialize the pause control quantity BL of the protection function block to a protection function pause state;

[0024] The port voltage acquisition module is used to collect the voltage of each series port of the converter valve test circuit and the voltage of the pole line capacitor port;

[0025] A monitoring quantity determination module, configured to determine an instantaneous value of the monitoring quantity and a maximum value of the monitoring quantity within a preset time according to the voltages of the series ports and the voltages of the polar line capacitor ports;

[0026] The short-circuit fault monitoring module is used to monitor the short-circuit fault in the DC voltage area of the converter valve test circuit based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within a preset time.

[0027] An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the DC voltage area short-circuit fault monitoring method of the converter valve test circuit is implemented.

[0028] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for monitoring a DC voltage area short-circuit fault in the converter valve test circuit is implemented.

[0029] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the above-mentioned method for monitoring short-circuit faults in the DC voltage area of the converter valve test loop.

[0030] The embodiment of the present invention initializes the suspension control quantity BL of the protection function block to a protection function suspension state; collects the voltages of each series port and the pole line capacitor port of the converter valve test circuit; determines the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within a preset time based on the voltages of each series port and the pole line capacitor port; and performs short-circuit fault monitoring in the DC voltage region of the converter valve test circuit based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity, and the maximum value of the monitoring quantity within a preset time. The embodiment of the present invention does not require the addition of excessive measuring point equipment and protection equipment, does not require excessive signal interaction between control and protection systems, and does not require the acquisition of state quantity signals such as shorted busbars. After a one-time commissioning, there is no need to modify the set value or manually switch the protection function. The DC voltage region short-circuit fault monitoring in the converter valve test circuit is performed based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity, and the maximum value of the monitoring quantity within a preset time. This avoids the risks associated with manually configuring protection switching and manually setting set values when conducting tests on test products of different voltage levels for flexible power supply input schemes, significantly shortens the monitoring and judgment time when short-circuit faults occur in the DC voltage region, and ensures safe and reliable operation of the test system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0032] Figure 1 Schematic diagram of a method for monitoring a DC voltage area short-circuit fault in a converter valve test circuit according to an embodiment of the present invention;

[0033] Figures 2 and 3 Schematic diagram of DC voltage area short circuit fault monitoring of a converter valve test circuit in a specific embodiment of the present invention;

[0034] Figure 4 This is a structural diagram of a DC voltage area short-circuit fault monitoring device for a converter valve test circuit according to an embodiment of the present invention;

[0035] Figure 5 Schematic diagram of the computer device structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0037] First, the abbreviations of the embodiments of the present invention are defined:

[0038] BL: Pause control value of protection function block (logically generated, different from external throw-in / out control signal EN). If BL=1, the function is suspended.

[0039] T1: dynamic T1ms timer (timing length);

[0040] A: Maximum value of monitoring quantity within the preset time T1ms;

[0041] B: Instantaneous value of monitored quantity;

[0042] k: drop coefficient;

[0043] X0: protection over-limit value;

[0044] X1: out-of-limit parameter (logically generated value size, if it is greater than X0, it is out-of-limit);

[0045] T0: Protection over-limit time.

[0046] In order to monitor the DC voltage area short circuit fault of the converter valve test circuit and ensure the safe and reliable operation of the test system, the embodiment of the present invention provides a method for monitoring the DC voltage area short circuit fault of the converter valve test circuit, such as Figure 1 As shown, the method may include:

[0047] Step 101: Initialize the pause control value BL of the protection function block to the protection function pause state;

[0048] Step 102: collecting the voltages of the series terminals and the pole line capacitor terminals of the converter valve test circuit;

[0049] Step 103: Determine the instantaneous value of the monitored variable and the maximum value of the monitored variable within a preset time according to the voltages of the series ports and the voltage of the polar capacitor port;

[0050] Step 104: Perform short-circuit fault monitoring of the DC voltage region of the converter valve test circuit based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity, and the maximum value of the monitoring quantity within a preset time.

[0051] Depend on Figure 1 As shown, the embodiment of the present invention initializes the pause control quantity BL of the protection function block to the protection function pause state; collects the voltages of each series port and the pole line capacitor port of the converter valve test circuit; determines the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within a preset time according to the voltages of each series port and the pole line capacitor port; and performs DC voltage area short circuit fault monitoring of the converter valve test circuit according to the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within a preset time. The embodiment of the present invention does not require the addition of excessive measuring point equipment and protection equipment, does not require the addition of excessive signal interactions of the control and protection systems, and does not require the acquisition of status quantity signals such as short-circuited busbars. After a one-time adjustment, there is no need to modify the set value and manually switch on and off the protection function. The DC voltage area short-circuit fault monitoring of the converter valve test circuit is performed according to the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within the preset time. This avoids the risks brought about by the manual configuration of protection switching and manual setting of set values required for flexible power supply input schemes when testing products of different voltage levels. This greatly shortens the monitoring and judgment time when a short-circuit fault occurs in the DC voltage area, thereby ensuring the safe and reliable operation of the test system.

[0052] In order to reduce the investment of test institutions and enterprises in the planning and use stages of the converter valve synthesis test system for new construction and old renovation projects. When the system tests products of different voltage levels, the flexible power supply commissioning scheme brings great challenges to the protection scheme. The method of the embodiment of the present invention does not need to add too many measuring point equipment and protection equipment, does not need to increase too much signal interaction of the control and protection systems, does not need to obtain status quantity signals such as short-circuited busbars, and after a one-time adjustment, there is no need to modify the set value and manually activate or deactivate the protection function. Under the multi-variable power supply commissioning scheme, in conjunction with the functional testing of valve components of different voltage levels, the short-circuit fault monitoring in the DC voltage power supply area is optimized to ensure the safe and reliable operation of the test system.

[0053] Each step is analyzed in detail below.

[0054] In step 101, the suspension control amount BL of the protection function block is initialized to a protection function suspension state.

[0055] In specific implementation, after the loading program is started, global variables are initialized and assigned values; wherein the pause control quantity BL of the protection function block is initialized to the protection function pause state, that is, assigned a value of 1.

[0056] In step 102, the voltages of the series terminals and the pole line capacitor terminals of the converter valve test loop are collected.

[0057] During specific implementation, after initialization, the function loop logic of each cycle is entered to collect the voltage of each series port and the voltage of the polar line capacitor port.

[0058] In step 103, the instantaneous value of the monitoring variable and the maximum value of the monitoring variable within a preset time are determined according to the voltages of the series ports and the voltage of the polar capacitor port.

[0059] In one embodiment, each series port voltage includes: a first series port voltage and a second series port voltage, wherein the first series port voltage is a port voltage of the lowest level series power supply;

[0060] Determining the instantaneous value of the monitored quantity and the maximum value of the monitored quantity within a preset time according to the voltages of the series ports and the voltages of the polar line capacitor ports includes:

[0061] Comparing the voltage of the first series port with the voltage of the polar line capacitor port, and determining the instantaneous value of the first monitoring quantity and the maximum value of the monitoring quantity within the first preset time according to the comparison result;

[0062] The voltage of the first series port is subtracted from the voltage of the second series port, and the instantaneous value of the second monitored variable and the maximum value of the monitored variable within the second preset time are determined according to the result of the subtraction.

[0063] During specific implementation, the pole line voltage is compared with the port voltage of the lowest level series power supply, and the smaller one is taken. The instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within the preset time T1 are taken and sent to the data monitoring part of the first functional unit; the port voltages of other interval series power supplies are respectively differentiated, and the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within the preset time T1 are taken and sent to each monitoring functional unit.

[0064] In step 104, the DC voltage area short circuit fault monitoring of the converter valve test circuit is performed based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within a preset time.

[0065] In one embodiment, the DC voltage area short circuit fault monitoring of the converter valve test circuit is performed based on the trip logic state quantity of the protection function block, the instantaneous value of the monitoring quantity, and the maximum value of the monitoring quantity within a preset time, including:

[0066] If the trip logic state quantity of the protection function block is 1, the trip output lock waiting for reset state is entered.

[0067] In one embodiment, the DC voltage area short circuit fault monitoring of the converter valve test circuit is performed based on the trip logic state quantity of the protection function block, the instantaneous value of the monitoring quantity, and the maximum value of the monitoring quantity within a preset time, including:

[0068] If the trip logic state quantity of the protection function block is 2, the product of the maximum value of the monitored quantity and the drop coefficient within the preset time is compared with the instantaneous value of the monitored quantity. If the product of the maximum value of the monitored quantity and the drop coefficient within the preset time is greater than or equal to the instantaneous value of the monitored quantity, an over-limit parameter is generated and sent to the protection function block. If the product of the maximum value of the monitored quantity and the drop coefficient within the preset time is less than the instantaneous value of the monitored quantity, a non-over-limit parameter is generated and sent to the protection function block.

[0069] The protection function block updates the tripping logic state quantity according to the input over-limit parameters or non-over-limit parameters.

[0070] In one embodiment, the DC voltage area short circuit fault monitoring of the converter valve test circuit is performed based on the trip logic state quantity of the protection function block, the instantaneous value of the monitoring quantity, and the maximum value of the monitoring quantity within a preset time, including:

[0071] If the trip logic state quantity of the protection function block is 0, the rising edge and falling edge of the monitored quantity are determined according to the instantaneous value of the monitored quantity and the maximum value of the monitored quantity within the preset time;

[0072] If the rising edge of the monitored quantity exceeds the preset high threshold voltage value, the pause control quantity BL of the protection function block is set to the protection function activation state; if the falling edge of the monitored quantity is lower than the preset low threshold voltage value and the protection function timing is not activated, the pause control quantity BL of the protection function block is set to the protection function pause state.

[0073] In specific implementation, the trip logic state quantity (Trip state quantity) of the protection function block is judged: if Trip=0, the protection function enabling condition judgment is entered; if Trip=1, the trip output is locked and waits for reset. If Trip=2, the protection function activation timing state is entered, and the data is further compared.

[0074] When Trip=1, it means that a trip is in effect and waiting for manual confirmation and reset;

[0075] When Trip=2, it means that the timing of the protection function block has been activated. It only needs to continuously judge whether the maximum value A×drop coefficient k of the T1 period is greater than or equal to the instantaneous value B; if so, the over-limit parameter X1 is generated to be greater than the protection set value X0 and sent to the protection function block; if not, the non-over-limit parameter X1 is generated to be less than the protection set value X0 and sent to the protection function block;

[0076] When Trip=0, it means that no limit has been exceeded, and other conditions are analyzed. First, the protection function enabling condition is determined: if the rising edge of the monitored quantity exceeds the upper threshold voltage, BL=0 is enabled; if the falling edge of the monitored quantity is lower than the lower threshold voltage and the protection function timing is not activated, BL=1 is enabled; in other cases, BL remains unchanged.

[0077] When BL=0, first determine whether the maximum value A×drop coefficient k of the T1 period is greater than or equal to the instantaneous value B; if so, the T1 timer assignment time length T1 is reduced by 1 step, and then the over-limit parameter X1 is generated to be greater than the protection set value X0 and sent to the protection function block; if not, determine whether the maximum value A×drop coefficient k of the T1 period is less than or equal to the instantaneous value B [if yes, the maximum value A of the T1 period is updated to the instantaneous value B, the T1 timer is cleared to 0, and then the T1 timer is increased by 1 step; if not, the T1 timer is directly increased by 1 step], and then continue to determine whether the T1 timer is greater than or equal to the T1 duration [if yes, the T1 timer is cleared to 0, and the maximum value A of the T1 period is updated to the instantaneous value B, and then the non-over-limit parameter X1 is generated to be less than the protection set value X0 and sent to the protection function block]; when BL=1, the maximum value A of the T1 period is cleared to 0, the T1 timer is cleared to 0, and the non-over-limit parameter X1 is generated to be less than the protection set value X0 and sent to the protection function block.

[0078] The protection function block executes basic protection analysis subroutines based on inputs. These subroutines determine whether a function is enabled, whether a parameter exceeds a limit, and whether a protection setting has been reached. Trip status values 0 / 1 / 2 can be generated: 0 indicates no limit violation and the timer returns to 0; 1 indicates a trip output and a locked state awaiting reset; 2 indicates a parameter violation and the timer is activated (the timer has not yet returned to 0). The limit violation timing portion of the protection function block features fast acceleration and slow deceleration. When the output state Trip is 0 or 2, the next sampling and timing cycle begins; if it is 1, the circuit breaker trips.

[0079] A specific embodiment is given below to illustrate the specific application of the DC voltage area short-circuit fault monitoring of the converter valve test circuit in the embodiment of the present invention. Figures 2 and 3 This is a schematic diagram of short-circuit fault monitoring in the DC voltage region of a converter valve test circuit, according to a specific embodiment of the present invention. During the sampling and data preprocessing stages, this embodiment of the present invention considers the number of voltage sources in series, the location of measurement points, and the number of monitoring units configured. After data preprocessing and input to each monitoring unit, the same logical structure can be used. The specific number of monitoring units configured is determined based on the number of 6P bridge power supply groups in series. The voltages of each series port and the pole line capacitor port are collected. Except for the voltages of the total pole line and the lowest group, which are processed and entered into the same unit, each port voltage of each unit corresponds to a monitoring unit. This short-circuit fault monitoring method can be summarized into five parts: data preprocessing; protection timer status identification; function enable / disable determination; dynamic update of the reference 1p.u voltage; and protection output status determination. It should be noted that the system's normal operating voltage serves as the current required operating voltage for identification of the protection function, serving as the reference 1p.u. However, the required operating voltage varies depending on the test product, and this required voltage also changes during system startup and shutdown. Dynamic update of the reference 1p.u voltage refers to the dynamic update of the maximum value A of the monitored variable within a preset time T1ms.

[0080] This example uses two 6P bridge voltage sources connected in series as an example. DC voltage measurement points are configured for the series port voltages DCPT1 and DCPT2, and the pole capacitor port voltage DCPT3. Assume the system AC frequency is 50 Hz, and the protection system processing cycle is 1 ms. Whether the two series power sources are synchronized or any single output is connected, fault monitoring of the monitored variable is possible in the event of a power supply or pole short circuit. The protection module can be installed locally, with two monitoring units per module. Alternatively, the function can be integrated or added to a comprehensive protection device, adding two monitoring units. The protection function is enabled when the rising edge of the monitored variable exceeds 2.5 kV. The BL is disabled when the falling edge of the monitored variable falls below 2.0 kV and the protection function timing is not activated. Protection function parameters: The program's intermediate reference comparison constant is set to 500. If the limit is exceeded, parameter X1 is assigned a value of 1000; if the limit is not exceeded, parameter X1 is assigned a value of 200. Protection function judgment conditions: The monitored quantity drops to less than 30% within 10ms and lasts for 5ms, which means that the protection action conditions are met.

[0081] The implementation process is as follows:

[0082] 1. Start the device, load the program, initialize and assign values to global variables; the BL assignment of two units is 1, which is in the protection function exit state;

[0083] 2. Then enter the functional loop logic of each cycle;

[0084] 3. First, collect and obtain the voltages DCPT1 and DCPT2 of each series port and the voltage DCPT3 of the polar capacitor port;

[0085] 4. Then pre-process the sampled data (smoothing, converting into monitored quantities, etc.);

[0086] 5. Extract the smaller value min(DCPT3,DCPT1) of the pole line voltage and the port voltage of the lower-level series power supply as the monitoring quantity, then take the instantaneous value and the maximum value within a frequency cycle time, and send it to the data monitoring part of the first functional unit;

[0087] 6. Take the terminal voltage difference (DCPT2-DCPT1) of the high-potential series power supply as the monitoring quantity, take the maximum value within the instantaneous value and one frequency cycle time, and send it to the second monitoring function unit;

[0088] 7. Call the public variable parameters of the previous cycle;

[0089] 8. Then the two units perform the same logical processing and judgment respectively;

[0090] 9. First determine the Trip status;

[0091] When Trip=1, it means that a trip is in effect and waiting for manual confirmation and reset;

[0092] When Trip=2, it means that the timing of the protection function block has been activated. It only needs to continuously determine whether A×k≥B; if yes, assign 1000 to X1 and send it to the protection function block; if no, assign 200 to X1 and send it to the protection function block;

[0093] When Trip=0, it means no limit crossing has occurred, and other conditions are analyzed. First, the protection function enabling condition is determined: if the rising edge of the monitored value exceeds 2.5kV, BL is assigned a value of 0, and the protection function unit is enabled. If the falling edge of the monitored value is less than 2kV and the protection function timing is not activated, BL is assigned a value of 1, and the protection function unit is disabled. In other cases, BL remains unchanged.

[0094] When BL=0, first determine whether A×k≥B; if so, assign T1 to T1-1, then assign X1 to 1000 and send it to the protection function block; if not, determine whether A×k≤B [if yes, update parameters A=B, T1=0, then T1+1; if not, directly T1+1], then continue to determine whether T1≥10 [if yes, update parameters T1=0, A=B, then assign X1 to 200 and send it to the protection function block];

[0095] When BL=1, update parameters A=0, T1=0, and assign 200 to X1 and send it to the protection function block;

[0096] The protection function block will execute the basic protection analysis subroutine according to the input and generate the Trip status 0 / 1 / 2;

[0097] When the output state Trip is 0 or 2, it can enter the next sampling and timing cycle; if it is 1, it will trip.

[0098] The embodiments of the present invention are primarily targeted at test institutions and enterprises designing a synthetic converter valve test system. During the planning and implementation phases of new construction and renovation projects, this system reduces investment while also mitigating some safety monitoring risks during system operation. Through data preprocessing, the design of BL conditions, and the dynamic updating of the reference 1p.u voltage, the risks associated with manually configuring protection switching and setting constants when conducting tests on products at different voltage levels are avoided. Through the design of protection timer status recognition and the dynamic updating of the reference 1p.u voltage, the voltage monitoring constant settings are optimized, allowing for flexible definition of the pre-sag identification time, which can also be used for dv / dt monitoring. In this example, the monitoring and judgment time when a short-circuit fault occurs in the DC voltage area can be greatly shortened; by designing the BL conditions, the risk of large voltage fluctuation percentages during the system startup and shutdown stages, which may induce protection malfunction, is avoided; by adding the protection constituted by the present invention, the risk of existing protection refusing to operate due to voltage output failure of a certain 6P bridge or short circuit in the DC voltage area when the series power supply is fully put into operation but the output voltage is low is avoided; by adding the protection constituted by the present invention, the risk of the DC voltage area losing a certain short-circuit fault monitoring and protection capability after temporarily exiting the undervoltage protection of the test product during short-circuit current testing and other projects is avoided; by selecting the method constituted by the present invention, the risk of other solutions that may increase the cost of adding more measuring point devices and protection equipment, increasing control and protection interaction signals, and increasing the acquisition of loop status signal quantities is avoided.

[0099] No matter two thyristor 6P bridges are connected in series, or a thyristor 6P bridge and a diode 6P bridge are connected in series to form a DC voltage source, after configuring the inductance and capacitance of the DC port, a relatively stable DC voltage can be formed externally. Such a voltage source has more options for controlling the output, but it has certain challenges for detection and protection. In response to the situation where some short-circuit faults in the DC voltage area of this series voltage source cause the DC voltage to drop, a short-circuit fault monitoring method is invented. The present invention is applied to a system of a series voltage source. By updating the reference 1p.u voltage, it is avoided that when the series power supply is fully put into operation and the output is less than 1 / 2 of the rated voltage of the system, a short circuit occurs at the high-potential 6P bridge port, and the other 6P bridge quickly increases the voltage. Under the influence of the capacitor's support on the potential, several voltage measurement points do not reach the protection set value, and the transformer overcurrent protection does not reach the protection set value, resulting in a protection refusal to operate; it avoids the problem of the DC voltage area lacking a certain short-circuit fault monitoring and protection capability after temporarily exiting the undervoltage protection of the test product during short-circuit current testing and other projects; by updating the reference 1p.u voltage and determining whether the function is enabled or disabled, it avoids the problem of operating at a relatively high voltage. When low DC voltage is output, a short circuit occurs in the DC voltage area and the protection refuses to operate; at the same time, the need to manually calculate and set the voltage protection constant according to different voltage levels of test products is avoided; through the protection timer status identification; the status of the protection judgment output; the effect of data preprocessing, the monitoring and judgment time when a short circuit fault occurs in the DC voltage area is shortened; through the function enable and disable judgment, the need to manually switch on and off the voltage monitoring protection of a certain power supply group according to the use of the series power supply is avoided; the risk of false protection during the start-up and stop stages of the combined system is avoided; it avoids adding more conventional protection configurations, reducing investment costs and the complexity of signals other than PT sampling.

[0100] Based on the same inventive concept, embodiments of the present invention also provide a device for monitoring short-circuit faults in the DC voltage region of a converter valve test circuit, as described in the following embodiments. Because the principles underlying these solutions are similar to those of the method for monitoring short-circuit faults in the DC voltage region of a converter valve test circuit, the implementation of the device for monitoring short-circuit faults in the DC voltage region of a converter valve test circuit can be referenced to the implementation of the method, and any repetitive details will not be repeated.

[0101] Figure 4 FIG. 1 is a structural diagram of a DC voltage area short-circuit fault monitoring device for a converter valve test circuit according to an embodiment of the present invention. Figure 4 As shown, the DC voltage area short-circuit fault monitoring device of the converter valve test circuit includes:

[0102] The control amount initialization module 401 is used to initialize the pause control amount BL of the protection function block to the protection function pause state;

[0103] The port voltage acquisition module 402 is used to acquire the voltage of each series port and the voltage of the pole line capacitor port of the converter valve test loop;

[0104] A monitoring quantity determination module 403 is configured to determine an instantaneous value of the monitoring quantity and a maximum value of the monitoring quantity within a preset time according to the voltages of the series ports and the voltages of the polar capacitor ports;

[0105] The short-circuit fault monitoring module 404 is used to monitor the DC voltage area short-circuit fault of the converter valve test circuit based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within a preset time.

[0106] In one embodiment, the series port voltages include: a first series port voltage and a second series port voltage, wherein the first series port voltage is the port voltage of the lowest-level series power supply;

[0107] The monitoring quantity determination module 403 is further configured to:

[0108] Comparing the voltage of the first series port with the voltage of the polar line capacitor port, and determining the instantaneous value of the first monitoring quantity and the maximum value of the monitoring quantity within the first preset time according to the comparison result;

[0109] The voltage of the first series port is subtracted from the voltage of the second series port, and the instantaneous value of the second monitored variable and the maximum value of the monitored variable within the second preset time are determined according to the result of the subtraction.

[0110] Based on the above invention concept, Figure 5 As shown, an embodiment of the present invention further provides a computer device 500, including a memory 510, a processor 520, and a computer program 530 stored in the memory 510 and executable on the processor 520. When the processor 520 executes the computer program 530, the DC voltage area short-circuit fault monitoring method of the converter valve test circuit is implemented.

[0111] Based on the aforementioned inventive concept, an embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for monitoring a DC voltage area short-circuit fault in the converter valve test circuit is implemented.

[0112] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the above-mentioned method for monitoring short-circuit faults in the DC voltage area of the converter valve test loop.

[0113] The embodiment of the present invention initializes the suspension control quantity BL of the protection function block to a protection function suspension state; collects the voltages of each series port and the pole line capacitor port of the converter valve test circuit; determines the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within a preset time based on the voltages of each series port and the pole line capacitor port; and performs short-circuit fault monitoring in the DC voltage region of the converter valve test circuit based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity, and the maximum value of the monitoring quantity within a preset time. The embodiment of the present invention does not require the addition of excessive measuring point equipment and protection equipment, does not require excessive signal interaction between control and protection systems, and does not require the acquisition of state quantity signals such as shorted busbars. After a one-time commissioning, there is no need to modify the set value or manually switch the protection function. The DC voltage region short-circuit fault monitoring in the converter valve test circuit is performed based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity, and the maximum value of the monitoring quantity within a preset time. This avoids the risks associated with manually configuring protection switching and manually setting set values when conducting tests on test products of different voltage levels for flexible power supply input schemes, significantly shortens the monitoring and judgment time when short-circuit faults occur in the DC voltage region, and ensures safe and reliable operation of the test system.

[0114] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0115] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0116] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0117] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0118] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for monitoring a DC voltage short-circuit fault in a converter valve test circuit, characterized in that: include: Initialize the pause control amount BL of the protection function block to the protection function pause state; Collect the voltage of each series port and pole line capacitor port of the converter valve test circuit; Determine the instantaneous value of the monitored quantity and the maximum value of the monitored quantity within a preset time according to the voltages of the series ports and the voltage of the polar line capacitor port; According to the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within the preset time, the DC voltage area short circuit fault monitoring of the converter valve test circuit is carried out.

2. The method for monitoring a DC voltage area short circuit fault in a converter valve test circuit according to claim 1, wherein: The series port voltages include: a first series port voltage and a second series port voltage, wherein the first series port voltage is the port voltage of the lowest level series power supply; Determining the instantaneous value of the monitored quantity and the maximum value of the monitored quantity within a preset time according to the voltages of the series ports and the voltages of the polar line capacitor ports includes: Comparing the voltage of the first series port with the voltage of the polar line capacitor port, and determining the instantaneous value of the first monitoring quantity and the maximum value of the monitoring quantity within the first preset time according to the comparison result; The voltage of the first series port is subtracted from the voltage of the second series port, and the instantaneous value of the second monitored variable and the maximum value of the monitored variable within the second preset time are determined according to the result of the subtraction.

3. The method for monitoring a DC voltage area short circuit fault in a converter valve test circuit according to claim 1, wherein: Based on the tripping logic state of the protection function block, the instantaneous value of the monitoring value, and the maximum value of the monitoring value within the preset time, the DC voltage area short circuit fault monitoring of the converter valve test circuit is carried out, including: If the trip logic state of the protection function block is 1, the trip output lock waiting for reset state is entered; When the trip logic state is 1, it means that a trip is in effect.

4. The method for monitoring a DC voltage area short circuit fault in a converter valve test circuit according to claim 1, wherein: Based on the tripping logic state of the protection function block, the instantaneous value of the monitoring value, and the maximum value of the monitoring value within the preset time, the DC voltage area short circuit fault monitoring of the converter valve test circuit is carried out, including: If the trip logic state quantity of the protection function block is 2, the product of the maximum value of the monitored quantity and the drop coefficient within the preset time is compared with the instantaneous value of the monitored quantity. If the product of the maximum value of the monitored quantity and the drop coefficient within the preset time is greater than or equal to the instantaneous value of the monitored quantity, an over-limit parameter is generated and sent to the protection function block. If the product of the maximum value of the monitored quantity and the drop coefficient within the preset time is less than the instantaneous value of the monitored quantity, a non-over-limit parameter is generated and sent to the protection function block. The protection function block updates the tripping logic state quantity according to the input over-limit parameters or non-over-limit parameters; When the trip logic state quantity is 2, it means that the timing of the protection function block has been activated.

5. The method for monitoring a DC voltage area short circuit fault in a converter valve test circuit according to claim 1, wherein: Based on the tripping logic state of the protection function block, the instantaneous value of the monitoring value, and the maximum value of the monitoring value within the preset time, the DC voltage area short circuit fault monitoring of the converter valve test circuit is carried out, including: If the trip logic state quantity of the protection function block is 0, the rising edge and falling edge of the monitored quantity are determined according to the instantaneous value of the monitored quantity and the maximum value of the monitored quantity within the preset time; If the rising edge of the monitored value exceeds the preset high threshold voltage value, the pause control value BL of the protection function block is set to the protection function enabled state; if the falling edge of the monitored value is lower than the preset low threshold voltage value and the protection function timing is not activated, the pause control value BL of the protection function block is set to the protection function pause state; When the trip logic state is 0, it means that no limit violation has occurred.

6. A DC voltage area short circuit fault monitoring device for a converter valve test circuit, characterized in that: include: A control quantity initialization module is used to initialize the pause control quantity BL of the protection function block to a protection function pause state; The port voltage acquisition module is used to collect the voltage of each series port of the converter valve test circuit and the voltage of the pole line capacitor port; A monitoring quantity determination module, configured to determine an instantaneous value of the monitoring quantity and a maximum value of the monitoring quantity within a preset time according to the voltages of the series ports and the voltages of the polar line capacitor ports; The short-circuit fault monitoring module is used to monitor the short-circuit fault in the DC voltage area of the converter valve test circuit based on the tripping logic state quantity of the protection function block, the instantaneous value of the monitoring quantity and the maximum value of the monitoring quantity within a preset time.

7. The DC voltage area short-circuit fault monitoring device for a converter valve test circuit according to claim 6, characterized in that: The series port voltages include: a first series port voltage and a second series port voltage, wherein the first series port voltage is the port voltage of the lowest level series power supply; The monitoring quantity determination module is further configured to: Comparing the voltage of the first series port with the voltage of the polar line capacitor port, and determining the instantaneous value of the first monitoring quantity and the maximum value of the monitoring quantity within the first preset time according to the comparison result; The voltage of the first series port is subtracted from the voltage of the second series port, and the instantaneous value of the second monitored variable and the maximum value of the monitored variable within the second preset time are determined according to the result of the subtraction.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 5 is implemented.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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