CN-121332429-B - PT ferromagnetic resonance self-adaptive cooperative suppression method and system

CN121332429BCN 121332429 BCN121332429 BCN 121332429BCN-121332429-B

Abstract

The invention discloses a PT ferromagnetic resonance self-adaptive cooperative suppression method and system, which comprise the steps of sampling voltage signals, current signals and PT secondary side voltage signals monitored by a high-voltage end sensing unit in real time, calculating the primary side voltage change rate and harmonic content, controlling a neutral point reconstruction unit to be put into operation according to comparison of the calculated primary side voltage change rate and harmonic content with corresponding preset thresholds, damaging resonance conditions by changing neutral point grounding impedance, controlling an energy feedback unit to be put into operation after the neutral point reconstruction unit works, absorbing resonance energy, controlling the neutral point reconstruction unit and the energy feedback unit to be sequentially turned off after resonance threat elimination is detected, and starting active cooling of the high-voltage end sensing unit by utilizing residual energy in the energy feedback unit. According to the method, the voltage change rate and the harmonic content are monitored in real time, the neutral point reconstruction destructive resonance is triggered rapidly, the energy feedback unit is utilized to absorb and feed back energy, and finally the system safety recovery is realized.

Inventors

MA ZHIQUAN
LI PEI
WANG SONG
PAN XING
ZHU FEIBAI
XU QUNWEI
XIONG HONGTAO

Assignees

国网浙江省电力有限公司电力科学研究院

Dates

Publication Date: 20260508
Application Date: 20251217

Claims (10)

1. A PT ferroresonance adaptive collaborative suppression method, comprising: The method comprises the steps of sampling voltage signals, current signals and PT secondary side voltage signals monitored by a high-voltage end sensing unit in real time, and calculating the primary side voltage change rate and harmonic content; According to the calculated primary side voltage change rate and harmonic content, comparing the primary side voltage change rate and the harmonic content with corresponding preset thresholds, controlling a neutral point reconstruction unit, and destroying resonance conditions by changing neutral point grounding impedance; After the neutral point reconstruction unit works, the input energy feedback unit is controlled to absorb resonance energy and feed the resonance energy back to the power system; And after the elimination of the resonance threat is detected, the neutral point reconstruction unit and the energy feedback unit are controlled to be turned off in sequence, and the residual energy in the energy feedback unit is utilized to start active cooling of the high-voltage end sensing unit.
2. The PT ferroresonance adaptive collaborative suppression method according to claim 1, wherein the high-voltage side sensing unit is configured to collect PT primary side voltage and current signals in real time, and comprises a PTC thermistor and a current transformer connected in series; the neutral point reconstruction unit is connected between the PT neutral point and the ground and is formed by connecting a first switch and an adjustable inductor in series; The energy feedback unit is connected with the neutral point reconstruction unit in parallel and is formed by connecting a second switch, a bidirectional DC/AC converter and a direct current side supporting capacitor in series.
3. The PT ferroresonance adaptive collaborative suppression method according to claim 2, wherein the neutral point reconstruction unit is controlled according to the calculated primary side voltage change rate and harmonic content, and the resonance condition is destroyed by changing the neutral point ground impedance, which comprises the following steps: setting the primary side voltage change rate as a main criterion, and immediately triggering the first switch to be closed when the primary side voltage change rate exceeds a preset first threshold value to finish the input of the neutral point reconstruction unit; after the complete harmonic analysis is finished and the harmonic content is obtained, comparing the harmonic content with a preset second threshold value: If the harmonic content is smaller than or equal to a preset second threshold value, judging that the resonance characteristic does not appear, switching off the first switch, and throwing out the neutral point reconstruction unit; if the harmonic content is greater than a preset second threshold value, the ferromagnetic resonance is confirmed to occur, and the input of the neutral point reconstruction unit is maintained.
4. The PT ferroresonance adaptive collaborative suppression method according to claim 3, wherein the value of the adjustable inductance is determined as follows: When the neutral point reconstruction unit is put into, the system capacitance to ground and PT excitation inductance are estimated according to a current signal monitored by a current transformer and a PT secondary side voltage signal, and the main frequency of the current resonance is determined; Determining the type of the resonant frequency according to the main frequency, calculating a target value by adopting a corresponding formula, and adjusting the adjustable inductance to the target value; continuing monitoring, if resonance is not restrained, adjusting the adjustable inductor at a preset step length near a target value until resonance is restrained, and recording corresponding frequency and inductance values; if the resonance is suppressed, the adjustable inductance is kept at the target value, and the corresponding frequency and inductance value are recorded.
5. The PT ferroresonance adaptive collaborative suppression method according to claim 2, wherein after the neutral point reconstruction unit works, the input energy feedback unit is controlled to absorb the resonance energy and feedback the resonance energy to the power system, and the specific process is as follows: After the neutral point reconstruction unit acts, if the harmonic content is detected to be larger than a preset second threshold value within a preset time threshold value, closing a second switch, and starting an energy feedback unit; If the harmonic content is not detected within the preset first time threshold, directly closing the second switch when the time point of the preset first time threshold is reached, and starting the energy feedback unit; Resonant energy is absorbed to a direct-current side supporting capacitor through PWM modulation of a bidirectional DC/AC converter, and is inverted into power frequency energy to be fed back to a system or a load, so that smooth energy absorption and feedback are realized.
6. The PT ferroresonance adaptive collaborative suppression method according to claim 2, wherein after the elimination of resonance threat is detected, the neutral point reconstruction unit and the energy feedback unit are controlled to be turned off in turn, and active cooling of the high voltage side sensing unit is started by using residual energy in the energy feedback unit, which comprises the following steps: When the harmonic content is detected to be lower than a preset third threshold value and the duration reaches a preset second time threshold value, the first switch and the second switch are turned off in sequence; And comparing the temperature of the PTC thermistor detected in real time with a preset temperature threshold, and if the temperature of the PTC thermistor is higher than the preset temperature threshold, starting active cooling of the PTC thermistor by residual energy in the energy feedback unit until the temperature of the PTC thermistor is lower than a standard value.
7. A PT ferroresonance adaptive collaborative suppression system applied to the PT ferroresonance adaptive collaborative suppression method as set forth in any one of claims 1-6, comprising: The cooperative suppression module is used for monitoring signals in the circuit system, providing resonance ultra-early warning, changing the neutral point impedance parameter of the system instantaneously after resonance starts to destroy resonance conditions, and absorbing and feeding back resonance energy in the system; And the central control module is used for receiving the signals monitored by the cooperative suppression module and controlling the actions of the cooperative suppression module.
8. The adaptive collaborative suppression system of PT ferroresonance according to claim 7, wherein the collaborative suppression module includes a high voltage side sensing unit, a neutral point reconstruction unit, and an energy feedback unit, wherein, The high-voltage end sensing unit is connected between the PT primary side high-voltage end and the system bus and is used for collecting PT primary side voltage and current signals in real time, and comprises a PTC thermistor and a current transformer which are connected in series; the neutral point reconstruction unit is connected between the PT neutral point and the ground and is formed by connecting a first switch and an adjustable inductor in series; The energy feedback unit is connected with the neutral point reconstruction unit in parallel and is formed by connecting a second switch, a bidirectional DC/AC converter and a direct current side supporting capacitor in series.
9. The PT ferroresonant adaptive collaborative suppression system according to claim 8, further comprising a cooling module driven by a dc output of the energy feedback unit for rapid thermal dissipation of the PTC thermistor after detection of resonant threat elimination.
10. A computing device for PT ferroresonance adaptive collaborative suppression method, comprising: One or more processors, memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing the method of any of claims 1-6.

Description

PT ferromagnetic resonance self-adaptive cooperative suppression method and system Technical Field The invention relates to the technical field of overvoltage protection of power systems, in particular to a PT ferromagnetic resonance self-adaptive cooperative suppression method and system. Background PT (electromagnetic voltage transformer) ferroresonance is one of the most common and serious overvoltage faults in neutral point ungrounded systems. When the system is disturbed by operation overvoltage, single-phase ground fault recovery and the like, the PT iron core magnetic flux can be saturated rapidly, so that the excitation inductance of the PT iron core magnetic flux is in nonlinear jump, and then a resonant circuit is formed with the system grounding capacitance, neutral point voltage offset and rapid amplification of harmonic components are caused, and malignant accidents such as PT fuse blowing and even equipment insulation breakdown can be possibly caused. Currently, conventional ferroresonance suppression measures mainly include the following: And the fixed grounding resistance method is to serially connect a damping resistor with a fixed resistance value into the PT neutral point. The method is simple and reliable, but has fixed damping characteristics, and cannot adapt to the change of the running mode of the system (such as the change of the capacitance to ground caused by line switching). The damping effect is insufficient when the resistance value is selected to be too small, the normal zero sequence voltage measurement accuracy of the system can be affected when the resistance value is selected to be too large, and the PT is possibly subjected to overcurrent risk when the resistance value is in single-phase grounding. Primary detuner-typically a nonlinear resistive material is used. Although the volt-ampere characteristic has certain self-adapting capability, the essence is a passive energy consumption element, and the core principle of converting resonance energy into heat energy is still the conversion. This not only results in wasted energy, but also may affect device life due to long term heating, and there is a risk of thermal collapse at sustained resonance. The secondary microcomputer resonance elimination device triggers the switching resistor by monitoring the PT opening triangle voltage. The main bottleneck of the scheme is response lag, and the PT iron core is required to be waited for to be saturated deeply and the secondary side voltage distortion is fully developed to act, so that the PT iron core is difficult to realize rapid inhibition in a gold window period of resonance occurrence, and the optimal control time is easy to miss. In summary, there are general contradictions inherent in the prior art between "response speed and suppression depth", "adaptive capacity and system influence", "energy processing mode". The method has the advantages that the method is slow in response, advanced intervention cannot be achieved, the method is poor in adaptability, system parameter change cannot be dynamically tracked, or resonance energy is processed in a rough dissipation mode, so that additional thermal stability and economical efficiency problems are caused. Therefore, the power system is in urgent need of an intelligent self-adaptive cooperative inhibition scheme capable of realizing rapid early warning, active reconstruction and energy circulation. Disclosure of Invention The technical problem to be solved by the invention is to overcome the defects in the prior art, and provide a PT ferromagnetic resonance self-adaptive cooperative suppression method and a PT ferromagnetic resonance self-adaptive cooperative suppression system, which realize quick suppression of ferromagnetic resonance and safe system recovery through cooperative control of early warning reconstruction, energy management and self-adaptive recovery. To achieve the above object, in a first aspect, the present invention provides a PT ferroresonance adaptive collaborative suppression method, which includes: Sampling the voltage signal, the current signal and the PT secondary side voltage signal monitored by the high-voltage end sensing unit in real time, and calculating the primary side voltage change rate and the harmonic content; According to the calculated primary side voltage change rate and harmonic content, comparing the primary side voltage change rate and the harmonic content with corresponding preset thresholds, controlling a neutral point reconstruction unit, and destroying resonance conditions by changing neutral point grounding impedance; After the neutral point reconstruction unit works, the input energy feedback unit is controlled to absorb resonance energy and feed the resonance energy back to the power system; And after the elimination of the resonance threat is detected, the neutral point reconstruction unit and the energy feedback unit are controlled to be turned off in sequence, and the residual en