Method and device for measuring harmonic impedance

Abstract

The invention relates to a method and a device for measuring harmonic impedance. Aiming at the main error source in an 'incremental method' of the method for measuring the harmonic impedance, namely the problem of the synchronization of frequency deviation and two different time signal phase angles, the invention discloses a 'bisynchronous incremental method', and develops a corresponding testing instrument, wherein the first synchronization is that a reference phase is synchronized with the system cycle to solve the drifting problem of the reference phase; and the second synchronization is that the sampling frequency is synchronized with the system frequency by tracking the changes of the system frequency by a hardware phase lock circuit and generating the sampling frequency by the phase lock circuit. The device for measuring the harmonic impedance comprises a synchronous circuit of the sampling frequency and the system frequency and a synchronous circuit of the phase and the system cycle. The 'bisynchronous incremental method' solves the error problems caused by benchmark reference phases, system frequency fluctuations and the like in the 'incremental method'; the device has a simple principle and is easy to implement; and the method and the device reach the engineering application level and solve the problem of measuring the harmonic impedance in the generation of electricity.

Description

technical field

[0001] The invention relates to a harmonic impedance measurement method and a measurement device, belonging to the fields of power quality control and management, and power quality measurement methods and devices. Background technique

[0002] Harmonic impedance is an extremely important parameter in power production. Whether it is designing a power filter or evaluating the level of harmonics generated by interference loads, the system harmonic impedance is the most basic parameter; use harmonic power flow calculation software to analyze the system network It is a common method to obtain harmonic impedance by frequency scanning, but it is difficult to obtain high-frequency parameters of the network; in addition, the three-phase geometric parameters of the system are not completely symmetrical, and parameters such as capacitance between phases and to ground affect the accuracy of calculation results It is very large, which makes the calculation results deviate...

Examples

Embodiment 1

[0054] The experimental system is shown in the attached Figure 9 . The short-circuit capacity of the 10kV bus 19 is 319MVA; the transformer capacity is 315kVA, and the impedance voltage is 4.2%; the fundamental wave impedance of the 400kV bus 20 is 0.008+j0.023(Ω). The interference source is a six-pulse rectifier 21, and the DC resistance load 22 is two high-power resistors (100kVA / 5Ω / set). Use this system to carry out the actual measurement test to verify the "double synchronous incremental method" and the harmonic impedance measurement device 23 .

[0055] The synchronization signal is taken from the 220V side voltage signal of the lighting distribution transformer of the 110kV substation. In the test, one resistor is first put in, and then the second resistor is put in to generate disturbance, that is, to generate harmonic voltage and current increment, and to extract the harmonic voltage and current signals before and after the disturbance, respectively, according to fo...

technical field

[0001] The invention relates to a harmonic impedance measurement method and a measurement device, belonging to the fields of power quality control and management, and power quality measurement methods and devices. Background technique

[0002] Harmonic impedance is an extremely important parameter in power production. Whether it is designing a power filter or evaluating the level of harmonics generated by interference loads, the system harmonic impedance is the most basic parameter; use harmonic power flow calculation software to analyze the system network It is a common method to obtain harmonic impedance by frequency scanning, but it is difficult to obtain high-frequency parameters of the network; in addition, the three-phase geometric parameters of the system are not completely symmetrical, and parameters such as capacitance between phases and to ground affect the accuracy of calculation results It is very large, which makes the calculation results deviate...

Examples

Embodiment 1

[0054] The experimental system is shown in the attached Figure 9 . The short-circuit capacity of the 10kV bus 19 is 319MVA; the transformer capacity is 315kVA, and the impedance voltage is 4.2%; the fundamental wave impedance of the 400kV bus 20 is 0.008+j0.023(Ω). The interference source is a six-pulse rectifier 21, and the DC resistance load 22 is two high-power resistors (100kVA / 5Ω / set). Use this system to carry out the actual measurement test to verify the "double synchronous incremental method" and the harmonic impedance measurement device 23 .

[0055] The synchronization signal is taken from the 220V side voltage signal of the lighting distribution transformer of the 110kV substation. In the test, one resistor is first put in, and then the second resistor is put in to generate disturbance, that is, to generate harmonic voltage and current increment, and to extract the harmonic voltage and current signals before and after the disturbance, respectively, according to fo...

Images