A DC high-speed switch internal arcing withstand test circuit

Abstract

The present invention discloses an internal arcing tolerance test circuit for a DC high-speed switch, the test circuit includes a short-circuit circuit, a rectifier circuit and an arcing monitoring circuit; wherein: the short-circuit circuit includes a short-circuit auxiliary circuit breaker, an AC power supply and a short-circuit transformer; the AC power supply, the short-circuit auxiliary circuit breaker and the primary coil of the short-circuit transformer are connected in series in sequence to form a circuit; the rectifier circuit includes a first ammeter, a rectifier valve group, a reactor, a rectifier auxiliary circuit breaker and a current limiting resistor. The scenario of the internal arcing tolerance test of the DC high-speed switch can be equivalently simulated under the coordinated action of the short-circuit circuit, the rectifier circuit and the arcing monitoring circuit, and the equivalent simulation circuit can be used to verify the circuit breaker's ability to withstand the erosion of the system load DC current when it malfunctions or trips in the system operation state under the rated SF6 gas pressure of the circuit breaker.

Description

Technical Field

[0001] The invention relates to a test circuit, in particular to an internal arcing tolerance test circuit of a DC high-speed switch. Background Art

[0002] High speed switch (HSS) is mainly used in multi-terminal flexible DC transmission systems. The purpose of configuring a high speed switch is to achieve the online switching of the third station of the DC system and the high-speed isolation of DC line faults, thereby improving the reliability and availability of the entire DC system.

[0003] DC high-speed switches generally adopt open column circuit breakers. The operating mechanism can be hydraulic or spring. In order to cooperate with the multi-terminal system coordinated control and realize the online input and output of the sending end and the receiving end, the coordination requirements for the key performance parameters of the equipment are very high. The main features are as follows:

[0004] (1) It should have an inherent long-term overload capacity of not less than 1.05pu system rated transmission capacity (at the highest ambient temperature);

[0005] (2) Have strong DC arc tolerance capability;

[0006] (3) Capable of transferring no-charge current of DC line;

[0007] (4) It has a high opening speed and reliable mechanical action characteristics, and will not cause refusal to operate or malfunction.

[0008] The operating conditions of DC high-speed switches mainly include stable closing, disconnection transient process, stable disconnection and closing transient process. Under the four operating conditions encountered by HSS, the following capabilities are required:

[0009] 1. When the HSS is in the open state, the converter stations on both sides of the break are unlocked, and the DC voltage on both sides reaches the rated DC voltage and stabilizes. At this time, the HSS can be reliably closed.

[0010] 2. When the HSS is in the closed state, the converter station on one side of the break is locked. At the beginning, the DC voltage on the locked side remains unchanged, and the HSS should be able to open the gate reliably. Due to the discharge of the pole line PT resistance and other reasons, the voltage to the ground on the locked side gradually decreases. Therefore, before the high-speed switch is disconnected, the HSS should be able to withstand the gradually increasing terminal voltage.

[0011] 3. When a DC line fault occurs, the HSS power supply converter station quickly shifts phase, and the HSS load-side converter station quickly locks. Before the HSS trips, it needs to withstand a transient large current of about 100ms with an amplitude of tens of kA. The HSS trips after the current decays to 0.

[0012] 4. It should have the ability to withstand internal arcing for a short period of time. For example, the Wudongde flexible DC project requires an internal arcing tolerance of 3125A, 400ms, and 5 times. The Yunnan-Guizhou interconnection project requires an internal arcing tolerance of 3786A, 400ms, and 5 times. The insulating jacket should not be damaged after five arcing times.

[0013] 5. HSS needs to have reliable high-speed closing and opening mechanical performance. For example, the Wudongde project requires closing time <100ms and opening time <30ms.

[0014] 6. HSS does not need to have the performance of breaking DC current or fault current. However, it needs to have the ability to break the residual current of the DC line, which is generally around 20A.

[0015] Therefore, before applying HSS, its overall key performance, especially the DC arcing tolerance capability, needs to be tested and evaluated. However, there is currently no test and evaluation method for DC arcing tolerance capability. Summary of the invention

[0016] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a DC high-speed switch internal arcing withstand test circuit to test the HSS before using it to determine whether its DC arcing withstand capability meets the requirements. To achieve the above-mentioned purpose, the technical solution of the present invention is:

[0017] An internal arcing tolerance test circuit for a DC high-speed switch includes a short-circuit circuit, a rectification circuit, and an arcing monitoring circuit; wherein:

[0018] The short-circuit loop includes a short-circuit auxiliary circuit breaker, an AC power source and a short-circuit transformer; the AC power source, the short-circuit auxiliary circuit breaker and the primary coil of the short-circuit transformer are connected in series in sequence to form a loop;

[0019] The rectifier circuit includes a first ammeter, a rectifier valve group, a reactor, a rectifier auxiliary circuit breaker and a current limiting resistor; the rectifier valve group is connected to the secondary coil of the short-circuit transformer, and the first ammeter is installed on the coil connected to the rectifier valve and the secondary coil of the short-circuit transformer; one end of the current limiting resistor is connected to the input end of the rectifier valve group, and the other end is connected to one end of the rectifier auxiliary circuit breaker; one end of the reactor is connected to the output end of the rectifier valve group;

[0020] The arcing monitoring circuit includes a first voltmeter, a second voltmeter, a second ammeter and a characteristic parameter comprehensive monitoring device; the other end of the rectifier auxiliary circuit breaker is used to be connected to the DC high-speed switch under test; the characteristic parameter comprehensive monitoring device is used to monitor the DC high-speed switch under test to obtain the parameters required for the test; one end of the second ammeter is connected to the other end of the current limiting resistor, and the other end is respectively connected to the DC high-speed switch under test and grounded; one end of the first voltmeter is connected to the line connecting the second ammeter and the DC high-speed switch under test, and the other end is grounded; one end of the second voltmeter is connected to the line connecting the rectifier auxiliary circuit breaker and the DC high-speed switch under test, and the other end is grounded.

[0021] The rectifier valve group is composed of a bridge-type commutation valve composed of controllable commutation arms, which can be set to 6 pulses or 12 pulses.

[0022] The characteristic parameter comprehensive monitoring device is used to monitor the tested DC high-speed switch and includes:

[0023] Mechanical characteristics monitoring to obtain the time-contact speed and time-contact travel curves of the tested DC high-speed switch when T0 is opened;

[0024] Infrared monitoring to obtain the changes in the arc extinguishing chamber surface temperature caused by the arcing heat radiation of the tested DC high-speed switch;

[0025] Gas composition monitoring is used to obtain the generation and evolution of SF6 gas components during the arc tolerance process inside the tested DC high-speed switch.

[0026] The AC power source is an AC generator.

[0027] The reactor is a dry-type reactor.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] Through the coordinated action of the short-circuit circuit, the rectification circuit and the arc monitoring circuit, the scenario of the internal arc withstand test of the DC high-speed switch can be simulated equivalently. Through the equivalent simulation circuit, under the rated SF6 gas pressure of the circuit breaker, the circuit breaker's performance of withstanding the erosion of the system load DC current in the event of malfunction or tripping in the system operation state is verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A circuit schematic diagram of an internal arcing withstand test circuit of a DC high-speed switch provided by an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the circuit breaker arc chamber contact erosion state assessment system;

[0032] Figure 3 This is a schematic diagram of infrared monitoring of the arc extinguishing chamber;

[0033] Figure 4 Figure 2 is a schematic diagram of the temperature rise assessment process. DETAILED DESCRIPTION

[0034] The content of the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0035] Example:

[0036] See also Figure 1 As shown, the internal arcing withstand test circuit of the DC high-speed switch provided in this embodiment mainly consists of three circuits: a short-circuit circuit 100, a rectification circuit 200, and an arcing monitoring circuit 300.

[0037] The short-circuit loop 100 includes an auxiliary circuit breaker AB2, an AC generator G and a short-circuit transformer T. The AC generator G, the short-circuit auxiliary circuit breaker AB2 and the primary coil of the short-circuit transformer T are connected in series in sequence to form a loop.

[0038] The rectifier circuit 200 includes a first ammeter A1, a rectifier valve group V, a dry-type reactor L, a rectifier auxiliary circuit breaker AB1, and a current limiting resistor R. The rectifier valve group V is connected to the secondary coil of the short-circuit transformer T. The first ammeter A1 is installed on the coil connected to the rectifier valve V and the secondary coil of the short-circuit transformer T; one end of the current limiting resistor R is connected to the input end of the rectifier valve group V, and the other end is connected to one end of the rectifier auxiliary circuit breaker AB1; one end of the reactor L is connected to the output end of the rectifier valve group V.

[0039] The arcing monitoring circuit 300 includes a first voltmeter V1, a second voltmeter V2, a second ammeter A2 and a characteristic parameter comprehensive monitoring device 30; the other end of the rectifier auxiliary circuit breaker AB1 is used to connect with the tested DC high-speed switch T0; the characteristic parameter comprehensive monitoring device 30 is used to monitor the tested DC high-speed switch T0 to obtain the parameters required for the test; one end of the second ammeter A2 is connected to the other end of the current limiting resistor R, and the other end is respectively connected to the tested DC high-speed switch T0 and grounded; one end of the first voltmeter V1 is connected to the line connecting the second ammeter A2 and the tested DC high-speed switch T0, and the other end is grounded; one end of the second voltmeter V2 is connected to the line connecting the rectifier auxiliary circuit breaker AB1 and the tested DC high-speed switch T0, and the other end is grounded.

[0040] Through the coordinated action of the short-circuit circuit, the rectification circuit and the arc monitoring circuit, the scenario of the internal arc withstand test of the DC high-speed switch can be simulated equivalently. Through the equivalent simulation circuit, under the rated SF6 gas pressure of the circuit breaker, the circuit breaker's performance of withstanding the erosion of the system load DC current in the event of malfunction or tripping in the system operation state is verified.

[0041] In this test circuit, the test object (i.e. the DC high-speed switch T0 under test) starts to open from the closed position, and a DC current arc I flows between the arc contacts of the test object. dc (The specific amplitude is based on the calculated value of the most severe fault condition of the specific project, generally in the range of 3000-5000A);

[0042] The duration is t ac (The specific time is subject to the specific engineering soft straight valve protection locking time setting value, generally in the range of 300-500ms);

[0043] A total of n arc withstand tests are conducted, with the specific number of tests being determined based on the project's requirements for the electrical life of the equipment.

[0044] In the initial state, the tested DC high-speed switch T0 is in the closed state, and the auxiliary circuit breakers AB1 and AB2 are in the open state.

[0045] Parameter deviation requirements: DC amplitude I dc The deviation from the engineering requirements is ±10%, and the duration cannot exceed 0.5s. dc 2 The deviation of t is 0 to 10%.

[0046] Specifically, the rectifier valve group V is composed of a bridge-type commutation valve V composed of controllable commutation arms, which can be set to 6 pulses or 12 pulses. The characteristic parameter comprehensive monitoring device is used to monitor the DC high-speed switch under test, including:

[0047] Mechanical characteristics monitoring to obtain the time-contact speed and time-contact travel curves of the tested DC high-speed switch when T0 is opened;

[0048] Infrared monitoring to obtain the changes in the arc extinguishing chamber surface temperature caused by the arcing heat radiation of the tested DC high-speed switch;

[0049] Gas composition monitoring is used to obtain the generation and evolution of SF6 gas components during the arc tolerance process inside the tested DC high-speed switch.

[0050] Accordingly, this embodiment further provides a method for testing the internal arcing tolerance of a DC high-speed switch. The method adopts the above-mentioned test circuit and includes:

[0051] 1) Configure the test circuit parameters

[0052] According to the test current requirement and the rated voltage of the generator, adjust the short-circuit transformer ratio, and then adjust the dry-type reactor in the rectifier test circuit to enable the test side to generate a DC amplitude I dc of short-circuit current.

[0053] 2) Generate short-circuit current

[0054] Before the test circuit is short-circuited, the test product is in the closed position. After the test starts, the auxiliary circuit breaker AB2 is closed to short-circuit the circuit, and the short-circuit current is amplified by the short-circuit transformer T along with the coil turns ratio to generate the short-circuit current required by the test, and input into the rectifier valve of the rectifier circuit, and the current amplitude is recorded in real time by the ammeter A1.

[0055] 3) Rectification

[0056] In the rectifier circuit, the bridge converter valve V composed of controllable converter arms can be set to 6 pulses or 12 pulses. After the AC short-circuit current is rectified by the converter valve, the auxiliary circuit breaker AB1 is closed and the DC current is output. After being adjusted by the dry-type reactor L and the current limiting resistor R, the current amplitude I that meets the test requirements is generated. dc .

[0057] 4) Arc burning test and status monitoring

[0058] In the arc monitoring circuit, when the rated DC current flows through the tested DC high-speed switch T0, the tested DC high-speed switch T0 is controlled to open. As the contacts move rapidly relative to the opening switch, a DC arc is generated between the arc contacts. After the contacts are opened, the DC arc will continue to burn between the arc contacts for the required test time t. ac After that, the auxiliary circuit breaker AB2 disconnects the AC short circuit, cuts off the power supply, and the arc of the arc contact of the DC high-speed switch T0 under test gradually weakens and eventually extinguishes. At this point, a test is over. Perform n tests according to the test requirements. The test interval should be based on the time required for the test product temperature to return to the ambient temperature to avoid personal injury.

[0059] During the test, key parameters such as dynamic resistance, gas composition evolution, opening and closing speed, and infrared temperature rise of the arc extinguishing chamber are recorded respectively, and these parameters are used to analyze whether the performance of the tested DC high-speed switch meets the requirements.

[0060] Specifically, the dynamic resistance includes four key characteristic parameters, which are specifically defined as follows:

[0061] 1) Effective contact state of arc contact: During the opening and closing process of the circuit breaker, when the arc contact resistance is less than or equal to a certain threshold value (this value can be given by referring to the measured value of the dynamic contact resistance), the arc contact is considered to be in an effective contact state; when the contact resistance is greater than this value, the arc contact is considered to be in an invalid contact state and is in a separated state (not absolutely separated, but for the convenience of data analysis). Since the test current reaches more than 2000A during the dynamic resistance test, a short arcing phenomenon will occur when the arc contact metal is absolutely separated. It is inaccurate to use the infinite contact resistance as the absolute separation moment of the contact through testing means. Therefore, this application defines a certain threshold as the arc contact contact edge value, only to facilitate the trend analysis of test data.

[0062] 2) Effective contact displacement L (mm): During the opening and closing process of the circuit breaker, the contact displacement corresponding to the arc contact contact resistance being less than or equal to the threshold value (2000μΩ) just after the main contacts are separated is called the effective contact displacement.

[0063] 3) Cumulative contact resistance R accu (μΩ*mm): The cumulative value of the contact resistance at the sampling moment corresponding to the effective contact displacement. The sampling rate of the test instrument is 20k, that is, the corresponding contact resistance value is obtained every 0.05ms. The contact resistance within the effective contact displacement curve is integrated to obtain the cumulative contact resistance μΩ*mm.

[0064] 4) Average contact resistance R ave (μΩ / mm): The cumulative contact resistance divided by the effective contact displacement gives the average contact resistance μΩ / mm, which can better reflect the changes in contact resistance and effective contact displacement after contact erosion.

[0065] The dynamic resistance of the arc contact of the circuit breaker is measured before and after the arc test and at each test interval, the characteristic parameters of the arc contact erosion state are recorded, the arc contact resistance to arc erosion is evaluated, and the records in the following table are completed.

[0066]

[0067] When the effective contact displacement L of the arc contact is in the range of 0 to 5 mm, the average contact resistance decreases rapidly with the increase of the effective contact displacement. When the contact displacement is greater than 5 mm, the average contact resistance gradually becomes stable.

[0068] Before and after the arc withstand test, the changes in the size, length and weight of the arc contact should be recorded.

[0069] Disassemble the test prototype to measure the port dimensions and component weights of the moving and static arc contacts;

[0070] Weight change before and after the test (unit: g)

[0071]

[0072]

[0073] Changes in arc contact dimensions before and after the test (unit: mm)

[0074]

[0075] Among them, the evaluation method of the contact erosion state of the circuit breaker arc extinguishing chamber is as follows: Figure 2 As shown, the following steps are included:

[0076] Step 1: The user extracts the characteristic parameters of the circuit breaker arc chamber through dynamic resistance testing technology and inputs them into the evaluation system. The input data includes:

[0077] 1) Information on the circuit breaker to be evaluated: circuit breaker dispatch number, phase, voltage level, circuit breaker model, manufacturer, and commissioning time;

[0078] 2) Initial characteristic parameters of this type of circuit breaker: arc contact effective contact displacement L (mm); arc contact cumulative contact resistance R accu (μΩ*mm); average contact resistance of arc contact R ave (μΩ / mm);

[0079] 3) Characteristic parameters of the current state of the circuit breaker to be evaluated: effective contact displacement of arc contact L (mm); cumulative contact resistance of arc contact R accu (μΩ*mm); average contact resistance of arc contact R ave (μΩ / mm);

[0080] The second step: Based on the database (cumulative energy ablation fingerprint library; contact characteristic parameter association library; contact ablation state expert library), a comprehensive evaluation is performed on the characteristic parameters of the initial state and current state of the circuit breaker to be evaluated input in the first step, and the quantitative difference of the cumulative opening and closing energy and characteristic quantity association curve corresponding to the current ablation state of the arc contact is obtained respectively.

[0081] Step 3: Based on the results of the comprehensive analysis in the second step, complete the calculation of characteristic parameters and determine the ratio interval between the current effective contact displacement of the circuit breaker arc contact and the initial effective contact displacement.

[0082] Step 4: Evaluate the current state of the arc extinguishing chamber of the circuit breaker. If the ratio of the current effective contact displacement of the arc contact to the initial effective contact displacement is within the range of 80-100%, it is a normal ablation state; if the ratio is within the range of 60-80%, it is a slight ablation state; if the ratio is within the range of 40-60%, it is a moderate ablation state; if the ratio is within the range of 20-40%, it is a severe ablation state; if the ratio is within the range of <20%, it is an abnormal state;

[0083] During the internal arc test of the circuit breaker, the generation, growth and evolution trends of various characteristic components of SF6 gas in the arc extinguishing chamber are recorded. This data can serve as an important maintenance basis for this type of circuit breaker during operation, and is also an important indicator for evaluating the degree of ablation of the circuit breaker nozzle.

[0084] As for the opening and closing speed monitoring of the tested DC high-speed switch, a conventional speed sensor can be used and installed on the arm of the operating mechanism of the circuit breaker. When the tested DC high-speed switch T0 opens and closes, the data of opening and closing speed v-time t-action stroke l are transmitted in real time to the characteristic parameter comprehensive monitoring device for comprehensive processing, so that the measurement of mechanical characteristics can be completed.

[0085] When the internal arcing withstand test is carried out on the DC high-speed switch T0 under test, the arc contact continues to withstand the ablation of the arc tarc, and the temperature rise of the arc is radiated to the insulating jacket of the arc extinguishing chamber through the insulating gas heat, which will cause a temperature rise change of several K on the surface of the arc extinguishing chamber. Therefore, during the test, an infrared monitoring device is used based on infrared radiation temperature measurement technology to monitor the temperature rise change of the insulating jacket of the circuit breaker arc extinguishing chamber in real time, and the data is transmitted to the characteristic parameter comprehensive monitoring device for comprehensive analysis and evaluation. In the type test, the temperature rise test data will serve as an important basis for status evaluation after operation.

[0086] The circuit breaker has two arc extinguishing chambers. The temperature measurement points of each arc extinguishing chamber are respectively taken from the upper and lower layers, and the left, middle and right positions have a total of 6 points. Figure 3 shown.

[0087] After completing the temperature measurement, record the temperature rise (K) data as follows:

[0088]

[0089] Temperature rise assessment process Figure 4 As shown, including:

[0090] 1. During the arc withstand test of the circuit breaker, the temperature of the insulating jacket of the arc extinguishing chamber is monitored by infrared. The temperature rise test is carried out according to the principle of upper and lower layers and left, middle and right points. The temperature rise of each point is recorded as T2. The root variance processing of the temperature rise of the scattered points in the arc extinguishing chamber is performed to obtain the mean value T1.

[0091] 2. Is there any local overheating and the room temperature rise of the arc extinguishing room exceeds the average value T1 max? If not, the assessment is normal. If so, proceed to the next step of assessment.

[0092] 3. According to the temperature rise of the current-carrying conductor under normal arcing tolerance, the measured temperature rise of the jacket is inversely calculated to obtain the calculated value of the temperature rise of the current-carrying conductor.

[0093] 4. Whether the scattered point test values ​​of the arc extinguishing chamber outer sleeve exceed the first limit value T2 max1, if yes, it is evaluated as abnormal contact of the current-carrying conductor of the arc extinguishing chamber, if not, proceed to the next step of evaluation.

[0094] 5. Are there any values ​​in the scattered point test of the arc extinguishing chamber outer sleeve that exceed the first limit value T2 max2? If so, it is assessed that the contact of the current-carrying conductor of the arc extinguishing chamber has reached the attention value, and other auxiliary assessment measures should be taken. If not, the temperature rise assessment is terminated.

[0095] According to the test requirements, after n times of internal arcing tolerance, during the test, the DC high-speed switch T0 under test should not produce obvious external effects, that is, the test piece cannot explode, and no holes or cracks can be produced on its casing, which means that it meets the internal arcing tolerance performance requirements.

[0096] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A DC high-speed switch internal arcing withstand test circuit, characterized in that: It includes short-circuit circuit, rectification circuit and arc monitoring circuit; among which: The short-circuit loop includes a short-circuit auxiliary circuit breaker, an AC power source and a short-circuit transformer; the AC power source, the short-circuit auxiliary circuit breaker and the primary coil of the short-circuit transformer are connected in series in sequence to form a loop; The rectifier circuit includes a first ammeter, a rectifier valve group, a reactor, a rectifier auxiliary circuit breaker and a current limiting resistor; the rectifier valve group is connected to the secondary coil of the short-circuit transformer, and the first ammeter is installed on the coil connected to the rectifier valve and the secondary coil of the short-circuit transformer; one end of the current limiting resistor is connected to the input end of the rectifier valve group; one end of the reactor is connected to the output end of the rectifier valve group; The arcing monitoring circuit includes a first voltmeter, a second voltmeter, a second ammeter and a characteristic parameter comprehensive monitoring device; the other end of the rectifier auxiliary circuit breaker is used to connect to the DC high-speed switch under test; the characteristic parameter comprehensive monitoring device is used to monitor the DC high-speed switch under test to obtain the parameters required for the test; one end of the second ammeter is connected to the other end of the current limiting resistor, and the other end is respectively connected to the DC high-speed switch under test and grounded; one end of the first voltmeter is connected to the line connecting the second ammeter and the DC high-speed switch under test, and the other end is grounded; one end of the second voltmeter is connected to the line connecting the rectifier auxiliary circuit breaker and the DC high-speed switch under test, and the other end is grounded; The arcing monitoring circuit also includes a characteristic parameter comprehensive monitoring device, which is used to monitor the DC high-speed switch under test to obtain parameters required for the test; The rectifier valve group is composed of a bridge-type commutation valve composed of controllable commutation arms, which can be set to 6 pulses or 12 pulses.

2. The internal arcing withstand test circuit of a DC high-speed switch according to claim 1, characterized in that: The characteristic parameter comprehensive monitoring device is used to monitor the tested DC high-speed switch and includes: Mechanical characteristics monitoring to obtain the time-contact speed and time-contact travel curves of the tested DC high-speed switch when T0 is opened; Infrared monitoring to obtain the changes in the arc extinguishing chamber surface temperature caused by the arcing heat radiation of the tested DC high-speed switch; Gas composition monitoring is used to obtain the generation and evolution of SF6 gas components during the arc tolerance process inside the tested DC high-speed switch.

3. The internal arcing withstand test circuit of a DC high-speed switch according to claim 1, characterized in that: The AC power source is an AC generator.

4. The internal arcing withstand test circuit of a DC high-speed switch according to claim 1, characterized in that: The reactor is a dry-type reactor.

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