CN-122017392-A - Online measurement method and device for capacitance current of distribution network to ground and electronic equipment

CN122017392ACN 122017392 ACN122017392 ACN 122017392ACN-122017392-A

Abstract

The invention provides an online measurement method of capacitance current of a power distribution network to the ground, which relates to the technical field of power system measurement, and comprises the steps of injecting a sinusoidal alternating current signal into an opening triangle of an electromagnetic voltage transformer of the power distribution network; the method comprises the steps of obtaining an initial phase angle of a sinusoidal alternating current signal to be zero, obtaining a voltage response signal generated by an acquired power distribution network bus during injection of the sinusoidal alternating current signal, extracting a direct-current bias voltage component from the voltage response signal, determining an equivalent capacitance to ground of the power distribution network based on the direct-current bias voltage component, and determining total capacitance current of the power distribution network under rated voltage based on the equivalent capacitance to ground. The invention can realize the purpose of measuring the capacitance current of the power distribution network to the ground with online safety, low cost, high precision and strong anti-interference capability.

Inventors

LI YAN
PU XIA
HE YUAN
GENG RUI
ZHANG QIONGYUE
YANG DONG

Assignees

湖北省计量测试技术研究院

Dates

Publication Date: 20260512
Application Date: 20251231

Claims (10)

1. An online measurement method for capacitance current of a power distribution network to the ground is characterized by comprising the following steps: injecting a sinusoidal alternating current signal into an opening triangle of an electromagnetic voltage transformer of the power distribution network, wherein the initial phase angle of the sinusoidal alternating current signal is zero; acquiring a voltage response signal generated by an acquired power distribution network bus during the period of injecting a sinusoidal alternating current signal; Extracting a direct current bias voltage component from the voltage response signal; Based on the direct-current bias voltage component, determining an equivalent capacitance to ground of the power distribution network; And determining the total capacitance current of the power distribution network under the rated voltage based on the equivalent capacitance to ground.
2. The method for online measurement of capacitive current to ground in a power distribution network according to claim 1, characterized in that the sinusoidal ac current signal has a frequency ranging from 5Hz to 25Hz.
3. The method for online measurement of power distribution network capacitance-to-ground current according to claim 1, wherein the calculation formula of the equivalent capacitance-to-ground of the power distribution network is: Wherein, the Is the equivalent capacitance to ground of the distribution network, Is a component of the dc bias voltage, To apply an initial dc voltage of the distribution network prior to excitation, f is the frequency of the sinusoidal ac current signal, Is the amplitude of the sinusoidal ac current signal.
4. The method for online measurement of capacitance current to ground of a power distribution network according to claim 3, wherein the calculation formula of the total capacitance current of the power distribution network at rated voltage is: Wherein, the For the total capacitive current of the distribution network at rated voltage, Is the system power frequency of the power distribution network, Is the system phase voltage of the distribution network.
5. The method for online measurement of capacitance current to ground of a power distribution network according to claim 4, wherein the system power frequency is 60Hz.
6. The method for online measurement of capacitance current to ground of a power distribution network according to claim 1, wherein the frequency of the sinusoidal ac current signal satisfies: where f is the frequency of the sinusoidal alternating current signal, The voltage amplitude generated by the sine alternating current signal at the opening triangle of the electromagnetic voltage transformer is used, Is the rated voltage of the electromagnetic voltage transformer, Is the rated frequency of the electromagnetic voltage transformer.
7. The method for online measurement of capacitance current to ground in a power distribution network according to any one of claims 1-6, wherein extracting a dc bias voltage component from the voltage response signal comprises: Taking the direct-current bias voltage component to be extracted as a system variable of a Kalman filtering algorithm, and taking the voltage response signal as a control input of the Kalman filtering algorithm to construct a state prediction equation; constructing an error covariance prediction equation based on a process noise covariance for representing the change speed of the DC bias voltage component and a state transition matrix; determining a kalman gain based on the error covariance prediction equation and an observed noise covariance for characterizing the amplitude of the voltage response signal and superimposing measurement noise; And in the updating process of the Kalman filtering algorithm, updating the measured DC offset voltage component based on the state prediction equation and the Kalman gain until a final DC offset voltage component is obtained.
8. An on-line measurement device for capacitance current of a power distribution network to the ground, which is characterized by comprising: the injection module is used for injecting a sinusoidal alternating current signal at the opening triangle of the electromagnetic voltage transformer of the power distribution network, wherein the initial phase angle of the sinusoidal alternating current signal is zero; The acquisition module is used for acquiring voltage response signals generated by acquired power distribution network buses during the period of injecting sinusoidal alternating current signals; the extracting module is used for extracting a direct-current bias voltage component from the voltage response signal; The capacitance calculation module is used for determining the equivalent capacitance to the ground of the power distribution network based on the direct-current bias voltage component; And the current calculation module is used for determining the total capacitance current of the power distribution network under the rated voltage based on the equivalent capacitance to ground.
9. An electronic device comprising a memory and a processor, wherein, The memory is used for storing programs; The processor, coupled to the memory, is configured to execute the program stored in the memory, to implement the steps of the method for online measurement of capacitive current to ground of a power distribution network according to any one of claims 1 to 7.
10. A non-transitory computer readable storage medium, having stored thereon a computer program, which when executed by a processor, implements the steps of the method for online measurement of capacitance current to ground of a power distribution network according to any of claims 1 to 7.

Description

Online measurement method and device for capacitance current of distribution network to ground and electronic equipment Technical Field The invention relates to the technical field of power system measurement, in particular to an online measurement method and device for capacitance current of a power distribution network to ground and electronic equipment. Background The capacitance current to ground of the distribution network is a key parameter affecting the safe and stable operation of the system, and is directly related to arc extinction, overvoltage level and setting of a protection device during single-phase ground faults. The traditional capacitance to ground measurement method has a plurality of defects: 1. The off-line measurement method is characterized in that the off-line measurement method needs power failure operation, a special capacitor bridge is used, the efficiency is low, and the real-time running state of the power grid can not be reflected. 2. The signal injection method is to inject different frequency AC signal (such as signal higher than power frequency) into the system and calculate impedance by measuring voltage and current vector. This method requires an expensive signal source and a precise phase measurement unit, is complex in system, and is susceptible to background harmonic interference. 3. The fault wave recording method is to analyze transient signals when a single-phase earth fault occurs in the system, but the system belongs to passive measurement, is uncontrollable and has limited fault machines. Therefore, there is an urgent need for a method for measuring the capacitance current of a power distribution network to ground, which is capable of being online, safe, low-cost, high-precision and high in anti-interference capability. Disclosure of Invention In view of the foregoing, it is necessary to provide an online measurement method, device and electronic equipment for measuring the capacitance current of a power distribution network, so as to achieve the purpose of measuring the capacitance current of the power distribution network with online safety, low cost, high precision and strong anti-interference capability. In order to solve the above problems, the present invention provides an online measurement method for capacitance current to ground of a power distribution network, including: injecting a sinusoidal alternating current signal into an opening triangle of an electromagnetic voltage transformer of the power distribution network, wherein the initial phase angle of the sinusoidal alternating current signal is zero; acquiring a voltage response signal generated by an acquired power distribution network bus during the period of injecting a sinusoidal alternating current signal; Extracting a direct current bias voltage component from the voltage response signal; Based on the direct-current bias voltage component, determining an equivalent capacitance to ground of the power distribution network; And determining the total capacitance current of the power distribution network under the rated voltage based on the equivalent capacitance to ground. In one possible implementation, the sinusoidal alternating current signal has a frequency in the range of 5Hz to 25Hz. In one possible implementation, the calculation formula of the equivalent capacitance to ground of the power distribution network is: Wherein, the Is the equivalent capacitance to ground of the distribution network,Is a component of the dc bias voltage,To apply an initial dc voltage of the distribution network prior to excitation, f is the frequency of the sinusoidal ac current signal,Is the amplitude of the sinusoidal ac current signal. In one possible implementation, the calculation formula of the total capacitance current of the power distribution network at the rated voltage is: Wherein, the For the total capacitive current of the distribution network at rated voltage,Is the system power frequency of the power distribution network,Is the system phase voltage of the distribution network. In one possible implementation, the system power frequency is 60Hz. In one possible implementation, the frequency of the sinusoidal alternating current signal satisfies: where f is the frequency of the sinusoidal alternating current signal, The voltage amplitude generated by the sine alternating current signal at the opening triangle of the electromagnetic voltage transformer is used,Is the rated voltage of the electromagnetic voltage transformer,Is the rated frequency of the electromagnetic voltage transformer. In one possible implementation, extracting a dc bias voltage component from the voltage response signal includes: Taking the direct-current bias voltage component to be extracted as a system variable of a Kalman filtering algorithm, and taking the voltage response signal as a control input of the Kalman filtering algorithm to construct a state prediction equation; constructing an error covariance prediction equation