Anti-resonance device of electromagnetic voltage transformer for GIS (Gas Insulated Switchgear)

Abstract

The invention provides an anti-resonance device of an electromagnetic voltage transformer for a GIS (Gas Insulated Switchgear). The anti-resonance device comprises a sub-harmonic anti-resonance circuit, a fundamental harmonic anti-resonance circuit and a higher harmonic anti-resonance circuit, the anti-resonance circuits are connected in parallel and then are connected to the PT opening triangle side. According to the sub-harmonic anti-resonance circuit, when sub-harmonic resonance occurs in a system, a nonlinear saturable reactor reaches a saturated state, and flowing current causes instantaneous loss, so that generation of the sub-harmonic resonance is inhibited; the fundamental harmonic anti-resonance circuit generates an electric field when current passes through an inductive element, and charges of the electric field are accumulated in a capacitor; two ends of the mutual inductor are connected in parallel or in series with a capacitor to form an LC series resonance circuit; the capacitor destroys resonance conditions in a loop to suppress fundamental harmonic waves; according to the high-order harmonic anti-resonance circuit, when voltage rise and current increase are detected, a high-power resistor in a secondary circuit enables zero sequence voltage to be in short circuit, inductance generated by mutual inductor overload changes resonance conditions in the secondary circuit, and high-order harmonics are eliminated. And the safety of the system is improved.

Description

Technical Field

[0001] The present invention relates to an anti-resonance device, and in particular to an electromagnetic voltage transformer anti-resonance device for GIS, which is mainly used in power systems and can be used in scenarios such as railway power supply systems, transmission lines, substations, distribution systems and power supply systems. Background Art

[0002] Overvoltage occurs frequently in power systems. The main causes of grid overvoltage include resonant overvoltage, operating overvoltage, lightning overvoltage, sudden changes in system operation mode, and system overvoltage caused by severe load fluctuations. Among them, the ferromagnetic resonance overvoltage hazard is more common and is also a more serious one. In a system with an ungrounded neutral point, the system closing at different times or the disappearance of a single-phase grounding fault will cause an instantaneous overvoltage in the electromagnetic voltage transformer (PT), thereby causing the core to saturate and produce ferromagnetic resonance. The overvoltage generated during ferromagnetic resonance can easily cause PT failure or even burning and power outages, which seriously threatens the safe and stable operation of the power grid. Summary of the invention

[0003] In view of the above technical problems, the present invention provides an electromagnetic voltage transformer anti-resonance device for GIS, comprising: a sub-harmonic anti-resonance circuit, a fundamental harmonic anti-resonance circuit and a high-order harmonic anti-resonance circuit; the sub-harmonic anti-resonance circuit, the fundamental harmonic anti-resonance circuit and the high-order harmonic anti-resonance circuit are connected in parallel to the open delta side of the PT;

[0004] The sub-harmonic anti-resonance circuit is a nonlinear saturable reactor; when sub-harmonic resonance occurs in the system, the non-linear saturable reactor reaches a saturated state, and the current flowing through the sub-harmonic anti-resonance device causes instantaneous loss, thereby suppressing the occurrence of sub-harmonic resonance;

[0005] The fundamental harmonic anti-resonance circuit includes a capacitor, an inductive element and a switch tube; when current passes through the inductive element, an electric field is generated, and the charge of the electric field is accumulated in the capacitor; a capacitor is connected in parallel or in series at both ends of the electromagnetic voltage transformer to form an LC series resonant circuit, and the LC series resonant circuit is used to offset the capacitive load of the inductive element to stabilize the resonant frequency protection; when the capacitor is put into the power transmission circuit, the resonant condition in the circuit is destroyed to suppress the fundamental harmonic;

[0006] The high-order harmonic anti-resonance circuit is a high-power resistor; when it is detected that the voltage rises and the current increases, the high-power resistor in the secondary circuit of the high-order harmonic anti-resonance circuit short-circuits the zero-sequence voltage, and changes the resonant condition in the secondary circuit to eliminate high-order harmonics by changing the inductance generated by the overload of the electromagnetic voltage transformer in the transmission line.

[0007] Furthermore, the nonlinear saturable reactor is formed by connecting an iron core reactor with saturation characteristics and a damping resistor in series.

[0008] Furthermore, the iron core reactor at the rated frequency ω N The impedance is high when When the frequency is divided, the magnetic flux is saturated by n times, and the frequency decreases, the impedance becomes lower, and the current of the damper circuit increases. S The required damping power can be obtained, thereby consuming the energy of the subharmonic resonance, destroying the resonance condition and suppressing the subharmonics.

[0009] Furthermore, high-power resistors have positive temperature characteristics under normal circumstances. Due to their small resistance values, the PTs in phases A, B, and C are equivalent to a short-circuit state. When the secondary excitation charge increases, the excitation reactance corresponding to the primary winding increases, changing the reactance value in the resonant circuit. After multiple cycles, the resonance is eliminated and will not cause harm to the voltage transformer.

[0010] Furthermore, it also includes: after voltage is applied to the electromagnetic voltage transformer, the PTC resistance value continues to increase; until it is detected that the voltage, current and frequency return to normal, the PTC resistance value is infinite and opens the circuit in the secondary circuit, and at the same time QS disconnects the circuit and exits operation.

[0011] The present invention provides an anti-resonance device for an electromagnetic voltage transformer for GIS. When a resonance phenomenon occurs, it detects and determines whether it is fundamental resonance, subharmonic resonance, or high-order harmonic resonance, and then drives the corresponding anti-resonance circuit to work to destroy the resonance conditions in the transmission line, so that it can work normally, prevent insulation damage to power equipment, and improve the safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a principle circuit diagram of a medium-speed saturated reactor type damper in a subharmonic anti-resonance circuit provided by an embodiment of the present invention;

[0013] Figure 2 is a principle circuit diagram of a fundamental harmonic anti-resonance circuit provided by an embodiment of the present invention;

[0014] Figure 3 is a schematic diagram of a high-order harmonic anti-resonance circuit provided by an embodiment of the present invention;

[0015] Figure 4 It is a working principle diagram of an anti-resonance device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0017] The present invention provides an electromagnetic voltage transformer anti-resonance device for GIS, comprising: a sub-harmonic anti-resonance circuit, a fundamental harmonic anti-resonance circuit and a higher harmonic anti-resonance circuit; the sub-harmonic anti-resonance circuit, the fundamental harmonic anti-resonance circuit and the higher harmonic anti-resonance circuit are connected in parallel to the open delta side of the PT;

[0018] like Figure 1 As shown, the sub-harmonic anti-resonance circuit is a nonlinear saturable inductor. When sub-harmonic resonance occurs in the system, the nonlinear saturable inductor reaches a saturated state, and the current flowing through the sub-harmonic anti-resonance device causes instantaneous loss, thereby suppressing the occurrence of sub-harmonic resonance.

[0019] Nonlinear saturable reactor, under normal conditions, this device flows through negligible current, so the loss is very small. The connection of the device will not affect the normal operation of the system. When the system has sub-harmonic resonance, the saturable reactor will reach saturation, and the current flowing through the device will cause a momentary loss, thereby suppressing the occurrence of sub-harmonic resonance.

[0020] The nonlinear saturable reactor is formed by connecting an iron core reactor with saturation characteristics and a damping resistor in series. N The impedance is high when When the frequency is divided, the magnetic flux is saturated by n times, and the frequency decreases, the impedance becomes lower, and the current of the damper circuit increases. S The required damping power can be obtained, thereby consuming the energy of the subharmonic resonance, destroying the resonance condition and suppressing the subharmonics.

[0021] like Figure 2 As shown, the fundamental harmonic anti-resonance circuit includes a capacitor, an inductive element and a switch tube; when current passes through the inductive element, an electric field is generated, and the charge of the electric field is accumulated in the capacitor; a capacitor is connected in parallel or in series at both ends of the electromagnetic voltage transformer to form an LC series resonant circuit, and the LC series resonant circuit is used to offset the capacitive load of the inductive element to stabilize the resonant frequency protection; when the capacitor is put into the power transmission circuit, the resonant condition in the circuit is destroyed to suppress the fundamental harmonic;

[0022] like Figure 3As shown, the high-order harmonic anti-resonance circuit is a high-power resistor; when it is detected that the voltage rises and the current increases, the high-power resistor in the secondary circuit of the high-order harmonic anti-resonance circuit short-circuits the zero-sequence voltage, and changes the resonant condition in the secondary circuit to eliminate high-order harmonics by changing the inductance generated by the overload of the electromagnetic voltage transformer in the transmission line.

[0023] High-power resistors, under normal circumstances, have positive temperature characteristics. Due to the small resistance value, the PT in the three phases A, B, and C is equivalent to a short-circuit state. When the secondary excitation charge increases, the excitation reactance corresponding to the primary winding increases, changing the reactance value in the resonant circuit. After multiple cycles, the resonance is eliminated and will not cause harm to the voltage transformer. After applying voltage to the electromagnetic voltage transformer, the PTC resistance value continues to increase; until the voltage, current, and frequency are detected to return to normal, the PTC resistance value is infinite and the circuit is open in the secondary circuit, and QS disconnects the circuit and exits work.

[0024] like Figure 4 As shown, an electromagnetic voltage transformer anti-resonance device for GIS is used to detect the voltage, current and frequency in the circuit and compare and judge with the parameters set in the system.

[0025] When the frequency is lower than 50Hz and the voltage of each phase rises in turn and exceeds the line voltage, the device determines it as sub-harmonic resonance. The fast saturation reactor type damper in the sub-harmonic anti-resonance circuit starts to work, destroying the resonance condition in the circuit. At the same time, the protection circuit will automatically record, store, and automatically alarm and display the resonance information (time, frequency, voltage, current value). When it is detected that the voltage, current, and frequency return to normal, the sub-harmonic anti-resonance circuit will stop working.

[0026] When the frequency is 50Hz and the two-phase voltage rises above the line voltage (2 to 3 times), the device determines that it is fundamental harmonic resonance, and the large-capacity capacitor in the fundamental harmonic anti-resonance circuit is put into operation to destroy the resonance condition in the circuit. At the same time, the protection circuit will automatically record, store, and automatically alarm and display the resonance information (time, frequency, voltage, current value). When it is detected that the voltage, current, and frequency return to normal, the circuit will exit the operation.

[0027] The present invention provides an anti-resonance device for an electromagnetic voltage transformer for GIS. When a resonance phenomenon occurs, it detects and determines whether it is fundamental resonance, subharmonic resonance, or high-order harmonic resonance, and then drives the corresponding anti-resonance circuit to work to destroy the resonance conditions in the transmission line, so that it can work normally, prevent insulation damage to power equipment, and improve the safety of the system.

[0028] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, 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 disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0029] 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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 flowchart and / or block diagram. 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.

[0030] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate 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 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0031] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalents that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An electromagnetic voltage transformer anti-resonance device for GIS, characterized in that: include: A sub-harmonic anti-resonance circuit, a fundamental harmonic anti-resonance circuit and a higher harmonic anti-resonance circuit; the sub-harmonic anti-resonance circuit, the fundamental harmonic anti-resonance circuit and the higher harmonic anti-resonance circuit are connected in parallel to the open triangle side of the PT; The sub-harmonic anti-resonance circuit is a nonlinear saturable reactor; when sub-harmonic resonance occurs in the system, the non-linear saturable reactor reaches a saturated state, and the current flowing through the sub-harmonic anti-resonance device causes instantaneous loss, thereby suppressing the occurrence of sub-harmonic resonance; A fundamental harmonic anti-resonance circuit, including a capacitor, an inductive element and a switch tube; When current passes through an inductive element, an electric field is generated, and the charge of the electric field is accumulated in the capacitor; a capacitor is connected in parallel or in series at both ends of the electromagnetic voltage transformer to form an LC series resonant circuit, which is used to offset the capacitive load of the inductive element and stabilize the resonant frequency protection; when the capacitor is put into the power transmission circuit, the resonant condition in the circuit is destroyed, thereby suppressing the fundamental harmonics; The high-order harmonic anti-resonance circuit is a high-power resistor; when it is detected that the voltage rises and the current increases, the high-power resistor in the secondary circuit of the high-order harmonic anti-resonance circuit short-circuits the zero-sequence voltage, and changes the resonant condition in the secondary circuit to eliminate high-order harmonics by changing the inductance generated by the overload of the electromagnetic voltage transformer in the transmission line.

2. The device according to claim 1, characterized in that The nonlinear saturable reactor is formed by connecting an iron core reactor with saturation characteristics and a damping resistor in series.

3. The device according to claim 2, characterized in that The iron core reactor at rated frequency ω N The impedance is high when When the frequency is divided, the magnetic flux is saturated by n times, and the frequency decreases, the impedance becomes lower, and the current of the damper circuit increases. S The required damping power can be obtained, thereby consuming the energy of the subharmonic resonance, destroying the resonance condition and suppressing the subharmonics.

4. The device according to claim 1, characterized in that Under normal circumstances, high-power resistors have positive temperature characteristics. Due to their small resistance values, the PTs in phases A, B, and C are equivalent to short-circuit states. When the secondary excitation charge increases, the excitation reactance corresponding to the primary winding increases, changing the reactance value in the resonant circuit. After multiple cycles, the resonance is eliminated and will not cause harm to the voltage transformer.

5. The device according to claim 4, characterized in that Also includes: After voltage is applied to the electromagnetic voltage transformer, the PTC resistance value continues to increase until the voltage, current and frequency are detected to return to normal, at which time the PTC resistance value becomes infinite and opens the secondary circuit, and at the same time QS disconnects the circuit and exits operation.

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