Transient Characteristics of RC Voltage Transformer

作者： GOZ Electric 时间：2024-11-23 09:43:57 阅读：16

Various high-voltage switch operations or transient fault conditions in the power system will produce great transient interference, which puts forward higher requirements on the transient response characteristics of the electronic voltage transformer. The principle structure of the RC voltage transformer of the 220 kV gas insulated switchgear (GIS) was studied, and the equivalent circuit model of the electronic voltage transformer was established. From the perspective of system simulation, the transient characteristics of the electronic voltage transformer under the single-phase grounding fault state of the substation were studied, and the parameter matching of the low-voltage arm capacitor and the voltage dividing resistor was determined to be an important factor affecting the transient characteristics of the voltage transformer, and a transient test verification of a grounding short circuit was carried out. Simulation and experimental studies show that the 220 kV GIS RC voltage transformer can transmit the transient changes of the primary voltage in real time and accurately under the single-phase grounding short circuit fault condition. This study is of great significance to improving the stability and reliability of the power system operation and promoting the practical application of electronic transformers under complex working conditions of smart substations.

Keywords: power system; transient interference; electronic voltage transformer; RC voltage division; transient characteristics; single-phase ground fault; parameter matching; transient test

With the development of smart grid, electronic voltage transformer based on RC voltage division principle has been widely used in voltage detection of smart substation. As a new type of voltage sensing equipment, RC voltage division type electronic transformer uses mature and reliable capacitor voltage division and digital acquisition technology to avoid iron core coil structure and complex insulation process, solve the problems of coil ferromagnetic resonance, poor transient response, high cost, etc., and is gradually applied to smart substations with higher voltage levels. The stability and reliability of RC voltage division type voltage transformer operation directly affect the accuracy of relay protection, metering and control of power system.

When high-voltage switch operation or transient fault occurs, great transient interference will be generated. Since the voltage transformer sensing component contains a capacitor energy storage element, it is susceptible to transient interference when matching the resistor to divide the voltage, resulting in poor transient response characteristics, so that the sensor output cannot reproduce the transient transition process of the primary voltage in a timely and accurate manner, thereby causing a delay in the rapid protection action or even malfunction.

Through the analysis of the sensing principle and transmission function of the RC voltage transformer, it can be seen that there are many factors that affect its transient characteristics, mainly including internal factors of the sensor such as the voltage dividing capacitor parameters and the voltage dividing resistor parameters, as well as external factors such as the fault voltage phase angle and the reliability of the grounding system. This paper combines the actual parameters of the RC voltage transformer of the 220 kV gas insulated switchgear (GIS), builds a circuit parameter model, analyzes the influence of the voltage transformer parameters on the output voltage waveform under the transient fault of a primary ground short circuit, and conducts transient performance test verification.

The transient overvoltage interference caused by various switch operations or short-circuit faults in the power system has a great impact on the electronic transformer, which may cause abnormal transient output of the voltage transformer. Based on the structural principle and product parameters of the 220 kV GIS RC voltage transformer, this paper conducts simulation and experimental research under single-phase short-circuit transient faults, and determines that the parameter matching of the low-voltage arm capacitor and the voltage-dividing resistor is an important factor affecting the transient characteristics of the voltage transformer.

During the primary ground short-circuit test, the steady-state and transient outputs of the 220 kV GIS RC voltage transformer studied in this paper are normal, and the transient transition process of the primary voltage can be transmitted and transformed in real time and accurately. This study plays a positive role in improving the stability and reliability of power system operation and promoting the practical application of electronic transformers under complex working conditions of smart substations.