GIS circuit breaker closing strategy method considering contact ablation

Abstract

The invention provides a GIS circuit breaker switching-on strategy method considering contact ablation, relates to the field of high-voltage electric appliance control, and solves the problem that the sending time of a switching-on action signal is not accurate due to the fact that the influence of contact ablation is not fully considered in an existing method. The method comprises the following steps: carrying out a dynamic resistance measurement test on GIS circuit breakers of the same model, determining dynamic resistance change data, fitting the dynamic resistance change data into a change relation curve related to contact resistance and stroke of the GIS circuit breakers and the number of times of breaking, and representing the ablation condition of the contact; the method comprises the following steps: acquiring historical operation data of a GIS circuit breaker in online operation, obtaining dynamic resistance during current opening, comparing the dynamic resistance with a change relation curve obtained in a dynamic resistance measurement test, determining a current contact ablation condition, and performing compensation adjustment on closing command sending time of the GIS circuit breaker next time according to the change relation curve; according to the invention, the excitation inrush current of different degrees generated during the no-load switching-on operation of the transformer can be effectively suppressed.

Description

Technical Field

[0001] The invention relates to the field of high-voltage electrical appliance control, is applied to a closing process of a GIS circuit breaker, and specifically relates to a GIS circuit breaker closing strategy method considering contact erosion. Background Art

[0002] Gas Insulated Switchgear (GIS) is a compact combination electrical device that encloses high-voltage electrical equipment such as circuit breakers, disconnectors, grounding switches, current transformers, voltage transformers, lightning arresters, busbars, various connectors and outgoing terminals in a grounded metal casing and is filled with sulfur hexafluoride (SF6) gas at a certain pressure as an insulating medium. GIS has been widely used in modern power systems due to its small footprint, high reliability and easy maintenance.

[0003] However, when GIS closes an unloaded transformer, the magnetic field in the transformer core changes, which will generate different degrees of excitation inrush current. This excitation inrush current not only contains obvious DC components, but also contains abundant harmonic components, which will lead to a decrease in power quality, increase power loss, and may cause a series of problems such as mechanical stress deformation of the transformer internal winding, differential protection malfunction, and resonant overvoltage, thus threatening the safe and stable operation of the power system.

[0004] In order to effectively deal with the above problems, the phase-selective closing technology of circuit breakers came into being. This technology aims to control the moving and static contacts of the circuit breaker to close at a specific phase angle of the system voltage waveform to reduce the impact of the power equipment on the system and itself when it is put into the power grid. Specifically, the phase-selective closing technology can make the power equipment complete the closing at an ideal position of the system voltage waveform, thereby minimizing the generation of excitation inrush current.

[0005] In the operation of modern intelligent switch stations, intelligent measurement and control devices are usually used to perform the opening and closing operations of circuit breakers. If the phase selection closing technology can be integrated into these intelligent measurement and control devices, the excitation inrush current generated when the circuit breaker is closed can be effectively suppressed without changing the external circuit structure, thereby improving the operating efficiency and safety of the system.

[0006] Despite this, the current traditional closing strategies still have certain limitations. They often ignore the problem of contact erosion and wear caused by arcing during long-term operation of the circuit breaker. Contact erosion and wear will affect the precise sending time of the closing action signal, thereby weakening the effect of phase selection closing technology. Therefore, how to further optimize the closing strategy to ensure accurate control of the closing phase even in the case of contact erosion and wear has become one of the key technical challenges that need to be solved urgently. Summary of the invention

[0007] Based on the current status of the background technology, the purpose of the present invention is to solve the problem that the existing GIS circuit breaker closing strategy does not fully consider the influence of contact erosion, resulting in inaccurate sending time of the closing action signal. Therefore, a GIS circuit breaker closing strategy method considering contact erosion is proposed. The present invention can effectively estimate the next pre-breakdown time and action time of the GIS circuit breaker by performing a dynamic resistance measurement test on the GIS circuit breaker, and then adjust the time when the closing command is issued; the present invention thus satisfies the effective suppression of different degrees of excitation inrush current generated during the no-load closing operation of the transformer.

[0008] The present invention adopts the following technical solutions to achieve the purpose:

[0009] A GIS circuit breaker closing strategy method considering contact erosion is disclosed. A dynamic resistance measurement test is performed on a GIS circuit breaker of the same model as an online GIS circuit breaker to determine the dynamic resistance change data of the GIS circuit breaker, and the change data is fitted into a change relationship curve of the contact resistance and stroke of the GIS circuit breaker and the number of openings, so as to characterize the contact erosion of the GIS circuit breaker under different numbers of openings. For the online GIS circuit breaker, the historical operation data of the GIS circuit breaker is monitored and obtained to obtain the dynamic resistance corresponding to the GIS circuit breaker at the time of the current opening. After comparing it with the change relationship curve obtained in the dynamic resistance measurement test, the current contact erosion of the GIS circuit breaker is determined, and then according to the change relationship curve, the time for issuing the closing command of the next GIS circuit breaker is compensated and adjusted.

[0010] Furthermore, for the GIS circuit breaker operating online, the contact collision signal and the voltage and current values ​​at both ends of the GIS circuit breaker are monitored, and the historical operation data of the pre-breakdown moment, the moment of just opening and closing, and the action time of the GIS circuit breaker are obtained after processing. According to the changes in the voltage and current values ​​when the circuit breaker is opened, the corresponding dynamic resistance is determined and compared with the change relationship curve.

[0011] Furthermore, by comparing the dynamic resistance corresponding to the last opening of the GIS circuit breaker with the change relationship curve, the pre-breakdown moment and action time of the next GIS circuit breaker can be predicted, thereby compensating and adjusting the time for issuing the closing command.

[0012] Furthermore, for the GIS circuit breaker in online operation, a vibration sensor is placed on the operating mechanism of the GIS circuit breaker, so that the closing moment of the GIS circuit breaker can be determined by measuring the vibration signal; at the same time, the corresponding voltage and current are continuously collected at both ends of the GIS circuit breaker through a voltage transformer and a current transformer, which serve as the historical operation data and the basis for determining the dynamic resistance at the time of the last opening, and then the closing strategy of the next GIS circuit breaker is determined as changing the phase angle of the grid voltage when closing.

[0013] Furthermore, by determining the dynamic resistance of the GIS circuit breaker when it is opened, and comparing it with the dynamic resistance change data determined by the change relationship curve, the contact erosion situation is obtained; based on the contact resistance and stroke, number of opening and closing times, voltage and current data information in the change relationship curve, the change in the pre-breakdown moment of the next GIS circuit breaker and the contact stroke is predicted through curve fitting, so that on the basis of the original initial action time of the next closing of the GIS circuit breaker, the adjustment action time of the next closing is compensated as the closing action target of the GIS circuit breaker, that is, the closing phase.

[0014] Preferably, when the GIS circuit breaker is closed, the time point when the current transformer detects the occurrence of current is taken as the current mutation point, and the moment of the current mutation point is taken as the pre-breakdown moment; based on the actual pre-breakdown moment and the just-closing moment of the online GIS circuit breaker, the corresponding historical operation data and the change relationship curve obtained in the dynamic resistance measurement test are compared and optimized, and the change relationship curve is updated according to the relationship between the contact resistance, pre-breakdown moment and action time in the change relationship curve as the number of openings and closing times changes.

[0015] Specifically, when conducting a dynamic resistance measurement test, a DC voltage source, a control switch, a GIS circuit breaker of the same model to be tested, a shunt and an adjustable resistor are connected in series to form a loop structure, which serves as a test loop for dynamic resistance measurement.

[0016] Furthermore, in the dynamic resistance measurement test, the GIS circuit breaker is repeatedly opened and closed for many times, and the dynamic resistance is recorded each time the GIS circuit breaker is opened. The dynamic resistance change data when the GIS circuit breaker is opened is obtained to characterize the contact erosion of the GIS circuit breaker under different opening times.

[0017] Specifically, in the dynamic resistance measurement test, the resistance value of the adjustable resistor is set so that the test current in the test circuit is a reference value during the test; after closing the GIS circuit breaker and the control switch of the same model being tested in sequence, the GIS circuit breaker is disconnected, and the dynamic resistance of the GIS circuit breaker measured by the test circuit is the ratio of the test voltage of the DC voltage source and the test current measured by the shunt.

[0018] Furthermore, the contacts in the GIS circuit breaker include main contacts and arc contacts. During each opening and disconnection process of the same type of GIS circuit breaker under test, the contact start movement time, main contact separation time and arc contact separation time of the GIS circuit breaker are determined based on the changes in the test voltage, test current and dynamic resistance of the process. At the same time, based on the contact stroke of the GIS circuit breaker, a change relationship curve is finally fitted.

[0019] In summary, due to the adoption of this technical solution, the beneficial effects of the present invention are as follows:

[0020] The present invention can effectively estimate the next pre-breakdown time and action time of the GIS circuit breaker by performing a dynamic resistance measurement test on the GIS circuit breaker, thereby adjusting the time of issuing the closing command according to the actual situation, so as to effectively suppress the different degrees of excitation inrush current generated during the transformer no-load closing operation. The present invention has good versatility and can adapt to the closing strategy requirements of GIS circuit breakers of different models and different voltage levels, thereby improving the application scope of the circuit breaker closing strategy.

[0021] In addition, the present invention significantly improves the contact monitoring efficiency. By only conducting a dynamic resistance measurement test on one GIS circuit breaker of the same model, the relationship between the contact erosion and the pre-breakdown moment and the action time can be obtained. When the subsequent GIS circuit breakers of the same model are monitored online, the degree of contact erosion can be evaluated based on the measured dynamic resistance value, and the pre-breakdown moment and the action time can be predicted accordingly, thereby reducing the inconvenience caused by regular power outages for maintenance.

[0022] At the same time, the present invention improves the closing accuracy. Compared with the traditional method of taking the mutation point of current and voltage as the just-closing moment and ignoring the pre-breakdown moment, the present invention determines the just-closing moment by collecting the contact collision signal of the running GIS circuit breaker, and obtains the pre-breakdown moment by measuring the voltage and current signals at both ends of the GIS circuit breaker, so that the closing action time is closer to the actual value, and the accuracy of the closing process is enhanced.

[0023] The present invention also improves the intelligence level of the overall system. By collecting dynamic resistance measurement results and data of GIS circuit breakers in operation, big data analysis can be used to evaluate the operating status of GIS circuit breakers, providing valuable historical information support for future intelligent operation, real-time monitoring and troubleshooting, which is conducive to subsequent intelligent upgrades and renovations, and further improves the reliability and maintenance efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The overall process diagram of the method of the present invention is briefly described;

[0025] Figure 2Schematic diagram of a test circuit for dynamic resistance measurement in the method of the present invention;

[0026] Figure 3 It is a schematic diagram of the results of dynamic resistance measurement in the method of the present invention;

[0027] Figure 4 It is a monitoring schematic diagram of an online GIS circuit breaker in the method of the present invention;

[0028] Figure 5 The figure is a schematic diagram of signal data of the closing process of the GIS circuit breaker in the method of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example

[0032] A GIS circuit breaker closing strategy method considering contact erosion. Figure 1 The overall process of the method is briefly shown and can be viewed simultaneously. The method is: a dynamic resistance measurement test is performed on a GIS circuit breaker of the same model as the GIS circuit breaker in online operation to determine the dynamic resistance change data of the GIS circuit breaker, and the change data is fitted into a change relationship curve of the contact resistance and stroke of the GIS circuit breaker and the number of openings, so as to characterize the contact erosion of the GIS circuit breaker under different numbers of openings; for the GIS circuit breaker in online operation, the historical operation data of the GIS circuit breaker is monitored and obtained to obtain the dynamic resistance corresponding to the GIS circuit breaker at the time of the current opening, and after comparing it with the change relationship curve obtained in the dynamic resistance measurement test, the current contact erosion of the GIS circuit breaker is determined, and then according to the change relationship curve, the time for issuing the closing command of the next GIS circuit breaker is compensated and adjusted.

[0033] This embodiment will provide a detailed description of the above method. Figure 2As shown in the figure, the test circuit of the dynamic resistance measurement test includes a DC voltage source U, a control switch CB, a GIS circuit breaker TCB of the same model to be tested, a shunt R1 and an adjustable resistor R2, which are connected in series to form a circuit structure. For a GIS circuit breaker, its contacts include main contacts and arc contacts; since the arc contacts have a large collision and bounce when in contact during closing, the instability of the contacts will cause a drastic change in the dynamic resistance to be measured, so the contact interval of the main and arc contacts cannot be distinguished from the resistance value, so the dynamic resistance during the closing process cannot represent the contact ablation of the GIS circuit breaker.

[0034] When the GIS circuit breaker is closed, it will be in a static contact state, and the static contact resistance is measured at this time. When entering the first stage of opening, the main contact and arc contact resistance exist at the same time; in the second stage, when the main contact is separated, only the arc contact resistance exists; in the third stage, the arc contact is separated and the resistance value becomes larger. It can be seen that the dynamic resistance of opening is more stable than that of closing, and the difference between the main and arc contact resistances is obvious. Therefore, this embodiment uses the dynamic resistance change data of the GIS circuit breaker when opening to characterize the contact ablation of the GIS circuit breaker under different breaking times.

[0035] In order to facilitate understanding of the measurement process proposed in this embodiment, in this embodiment, by setting the resistance value of the adjustable resistor R2, the test current I(t) in the test circuit is a reference value during the test. After closing the GIS circuit breaker TCB and the control switch CB of the same model to be tested in sequence, the GIS circuit breaker TCB is disconnected, and the dynamic resistance of the GIS circuit breaker measured by the test circuit is the ratio of the test voltage U(t) of the DC voltage source U and the test current I(t) measured by the shunt R1.

[0036] like Figure 3 As shown in the figure, the current, voltage and resistance test waveforms of the same type of GIS circuit breaker tested after opening and disconnection are divided into three obvious stages; in the first stage, before the opening command is issued, the voltage across the GIS circuit breaker is zero, the line current is maximum, and the break resistance is zero; in the second stage, after the opening command is issued, the contacts start to move at T0, and the main contacts are separated at T1. In this stage, the main contacts and arc contacts are connected in parallel. Since the resistance of the main contacts is much smaller than the resistance of the arc contacts, the contact resistance value during this stage is approximately the resistance of the main contacts. The current mainly flows through the main contacts. Because the pressure change during the overtravel process will cause the resistivity to change, the resistance value during this stage will fluctuate; the third stage is the stage from the separation of the main contacts to the separation of the arc contacts. In this stage, the arc contacts are in contact alone, and the dynamic resistance is the resistance of the arc contacts.

[0037] When the static main contact and the moving main contact are separated, the current on the main contact gradually transfers to the arc contact, and narrow pulses appear on the voltage and current curves; when the arc contact is separated, the SF6 gas blows the arc to extinguish it, and a wide pulse appears on the voltage curve, the current value drops significantly, and the contact resistance increases significantly. Based on the above principle, after multiple measurements of the dynamic resistance measurement test, the relationship between the contact resistance (i.e., contact resistance value), stroke, action time and other data of the GIS circuit breaker and the number of interruptions can be obtained, and the data can be fitted into a change relationship curve after collecting the data.

[0038] like Figure 4 As shown in the figure, in the closing strategy of the online GIS circuit breaker, the voltage and current are continuously collected through the voltage transformer and the current transformer at both ends of the GIS circuit breaker; at the same time, the vibration sensor is placed on the operating mechanism of the GIS circuit breaker. Assume that the primary side grid voltage u of the transformer in the line is U m cos(ωt+α), the primary winding resistance is R1, the inductance is L1, and the steady-state magnetic flux is Φ m , the remanence is Φ r , then after the GIS circuit breaker corresponding to the transformer was opened last time, when it is closed next time, the magnetic flux of the transformer is The excitation inrush current is i1 = N1Φ / L1. In order to reduce the excitation inrush current when closing the switch, it is necessary to reduce the transient magnetic flux. Therefore, the closing strategy of this embodiment is determined to change the phase angle α of the grid voltage when closing the switch.

[0039] In this embodiment, the dynamic resistance value is obtained by measuring the voltage and current at the last opening, and the dynamic resistance value is compared with the dynamic resistance value obtained from the dynamic resistance measurement test to obtain the degree of contact ablation. The predicted change in the pre-breakdown moment and the contact stroke is obtained through curve fitting, so that the adjustment action time of the next closing is compensated on the basis of the original initial action time of the next closing of the GIS circuit breaker, which is used as the closing action target of the GIS circuit breaker, that is, the closing phase, corresponding to the phase angle α.

[0040] In this embodiment, the vibration sensor installed on the operating mechanism of the online GIS circuit breaker is a piezoelectric vibration sensor. The vibration sensor uses the piezoelectric effect of the crystal to complete vibration measurement. When the vibration of the object to be measured forms pressure on the piezoelectric vibration sensor, the crystal element will generate corresponding electric charge, and the charge number can be converted into vibration parameters.

[0041] The current transformer is based on the principle of electromagnetic induction and consists of a closed iron core and windings. The primary winding has a small number of turns and is connected in series in the current circuit to be measured. The secondary winding has a large number of turns and is connected in series in the detection circuit. The structure of the voltage transformer is similar to that of the transformer. Both windings are installed on the iron core, and there is insulation between the windings and the iron core. When working, the primary winding is connected in parallel to the line, and the secondary winding is connected in parallel to the instrument.

[0042] like Figure 5 As shown, in this embodiment, when the GIS circuit breaker is closed, the time point when the current transformer detects the current is taken as the current mutation point, and the moment of the current mutation point is taken as the pre-breakdown moment. When the moving arc contact and the static arc contact collide, a bounce occurs. This vibration signal is used as the just-closed moment after data processing. The current is taken over by the arc contact, and the arc is extinguished as the moment when the pre-breakdown ends. According to the actual pre-breakdown moment and just-closed moment of the online GIS circuit breaker, the corresponding historical operation data is compared and optimized with the change relationship curve obtained in the dynamic resistance measurement test. The change relationship curve is updated according to the relationship between the contact resistance, pre-breakdown moment, and action time in the change relationship curve as the number of interruptions.

[0043] In summary, the method of this embodiment can determine the time when the closing signal is issued according to the required closing target phase through the change relationship curve of the online field measurement data and the dynamic resistance measurement test; taking into account the action time and contact erosion during the operation of the GIS circuit breaker, the excitation surge current during the closing process is ultimately effectively reduced.

Claims

1. A GIS circuit breaker closing strategy method considering contact erosion, characterized by: A dynamic resistance measurement test is carried out on GIS circuit breakers of the same model as the GIS circuit breakers in online operation to determine the dynamic resistance change data of the GIS circuit breaker, and the change data is fitted into a change relationship curve of the contact resistance and stroke of the GIS circuit breaker with the number of openings, so as to characterize the contact erosion of the GIS circuit breaker under different numbers of openings; for the GIS circuit breaker in online operation, the historical operation data of the GIS circuit breaker is monitored and obtained to obtain the dynamic resistance corresponding to the GIS circuit breaker at the time of the current opening. After comparing it with the change relationship curve obtained in the dynamic resistance measurement test, the current contact erosion of the GIS circuit breaker is determined, and then according to the change relationship curve, the time for issuing the next closing command of the GIS circuit breaker is compensated and adjusted.

2. The GIS circuit breaker closing strategy method considering contact erosion according to claim 1 is characterized in that: For the GIS circuit breaker in online operation, the contact collision signal and the voltage and current values ​​at both ends of the GIS circuit breaker are monitored. After processing, the historical operation data of the pre-breakdown moment, the moment of just opening and closing, and the action time of the GIS circuit breaker are obtained. According to the changes in the voltage and current values ​​at the time of opening, the corresponding dynamic resistance is determined and compared with the change relationship curve.

3. The GIS circuit breaker closing strategy method considering contact erosion according to claim 2 is characterized in that: By comparing the dynamic resistance corresponding to the last opening of the GIS circuit breaker with the change relationship curve, the pre-breakdown moment and action time of the next GIS circuit breaker can be predicted, so as to compensate and adjust the time of issuing the closing command.

4. The GIS circuit breaker closing strategy method considering contact erosion according to claim 2 is characterized in that: For the GIS circuit breaker in online operation, a vibration sensor is placed on the operating mechanism of the GIS circuit breaker, so that the closing moment of the GIS circuit breaker can be determined by measuring the vibration signal; at the same time, the corresponding voltage and current are continuously collected at both ends of the GIS circuit breaker through a voltage transformer and a current transformer, which are used as the historical operation data and the basis for determining the dynamic resistance at the time of the last opening, and then the closing strategy of the next GIS circuit breaker is determined as changing the phase angle of the grid voltage when closing.

5. The GIS circuit breaker closing strategy method considering contact erosion according to claim 4 is characterized in that: By determining the dynamic resistance of the GIS circuit breaker when it is opened, and comparing it with the dynamic resistance change data determined by the change relationship curve, the contact erosion situation can be obtained; based on the contact resistance and stroke, number of openings and closings, voltage and current data information in the change relationship curve, the change in the pre-breakdown moment of the next GIS circuit breaker and the contact stroke can be predicted through curve fitting, so that on the basis of the original initial action time of the next closing of the GIS circuit breaker, the adjustment action time of the next closing can be compensated as the closing action target of the GIS circuit breaker, that is, the closing phase.

6. The GIS circuit breaker closing strategy method considering contact erosion according to claim 5 is characterized in that: When the GIS circuit breaker is closed, the time point when the current transformer detects the current is taken as the current mutation point, and the moment of the current mutation point is taken as the pre-breakdown moment; according to the actual pre-breakdown moment and the just-closing moment of the online GIS circuit breaker, the corresponding historical operation data and the change relationship curve obtained in the dynamic resistance measurement test are compared and optimized, and the change relationship curve is updated according to the relationship between the contact resistance, pre-breakdown moment and action time in the change relationship curve as the number of disconnections changes.

7. The GIS circuit breaker closing strategy method considering contact erosion according to claim 1, characterized in that: When conducting a dynamic resistance measurement test, a DC voltage source, a control switch, a GIS circuit breaker of the same model to be tested, a shunt and an adjustable resistor are connected in series to form a loop structure, which serves as a test loop for dynamic resistance measurement.

8. The GIS circuit breaker closing strategy method considering contact erosion according to claim 7, characterized in that: In the dynamic resistance measurement test, the GIS circuit breaker is repeatedly opened and closed for many times, and the dynamic resistance is recorded each time the GIS circuit breaker is opened. The dynamic resistance change data when the GIS circuit breaker is opened is obtained to characterize the contact erosion of the GIS circuit breaker under different opening times.

9. The GIS circuit breaker closing strategy method considering contact erosion according to claim 8, characterized in that: In the dynamic resistance measurement test, the resistance value of the adjustable resistor is set so that the test current in the test circuit is the reference value during the test; after closing the GIS circuit breaker and the control switch of the same model under test in sequence, the GIS circuit breaker is disconnected, and the dynamic resistance of the GIS circuit breaker measured by the test circuit is the ratio of the test voltage of the DC voltage source and the test current measured by the shunt.

10. The GIS circuit breaker closing strategy method considering contact erosion according to claim 9, characterized in that: The contacts in the GIS circuit breaker include main contacts and arc contacts. During each opening and disconnection process of the same type of GIS circuit breaker under test, the contact start movement time, main contact separation time and arc contact separation time of the GIS circuit breaker are determined according to the changes in the test voltage, test current and dynamic resistance of the process. At the same time, based on the contact stroke of the GIS circuit breaker, the change relationship curve is finally fitted.

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