System for monitoring and orientating electric power quality pollution source in electric network

Abstract

The invention relates to a monitoring device, in particular to a system for monitoring and orientating an electric power quality pollution source in an electric network. The system provides the monitoring and the orientation of a voltage swell/dip pollution source in the electric network: a wavelet analysis method is used for the first time to capture the voltage swell/dip from the real-time voltage waveform, and as long as a corresponding transient course is monitored, the effective value change curve of the line current is monitored and whether the voltage swell/dip is related to the line is judged, thereby achieving the purposes of monitoring and orientation of the voltage swell/dip. Besides, the system further provides the monitoring and the orientation of a harmonic-wave pollution source and a flickering pollution source. The system realizes the function of the on-line orientation of the electric power quality pollution source for the first time, provides effective centralized processing for the power supply system, avoids the widespread propagation of the polluted signals, improves the power supply quality of the electric network, and provides the uniform standard and theoretical foundation for the solution of the electrical energy pollution source, thereby being of great significance to the technological development of the monitoring and the orientation of the pollution source in the electric network.

Description

technical field [0001] The invention relates to a monitoring device, in particular to a monitoring and orientation system for power quality pollution sources in a power grid. Background technique [0002] With the application of a large number of nonlinear power electronic components and the emergence of nonlinear loads, more and more waveform disturbances such as voltage interruption, short-term impact, flicker and notch are fed into the system from the user end, which has a great impact on the power system. Interference with normal operation. In addition, flashover or discharge of insulators caused by lightning strikes, various faults and oscillations caused by power system equipment may induce power system accidents, resulting in temporary interruption of power supply and reducing power supply reliability. [0003] There are many cases of poor power quality, and the sensitivity of users to power quality is also different. With the change of sensitivity of various electri...

AI Technical Summary

Problems solved by technology

However, the simple monitoring of power quality indicators only gives the sum of the impact of multiple compliances on the power grid, and cannot point out the source of power quality pollution, nor can it guide the determination of the optimal location for power quality control

[0004] Voltage swells and dips rarely occur in the power grid, but they are more harmful

With the application of large-scale sensitive power electronic devices such as computers and adjustable speed drives in control automation, a voltage surge or dip that lasts only a few tenths of a second may interrupt production and cause huge economic losses , voltage swells and dips are considered to be the most serious transient power quality problems affecting the normal operation of user equipment

However, due to the short duration and elusiveness of voltage swells and dips, its orientation has always been a difficult problem in engineering.

[0005] The traditional monitoring of power quality is mainly aimed at the monitoring of harmonic pollution sources, mainly using the critical impedance method and power flow method. The critical impedance method is based on theoretical assumptions, it is difficult to obtain actual parameters, it is not convenient for online application, and has no practical value

Now the power flow method is often used, which is based on the assumption that "the pollution source is to transmit energy outward". In fact, in a complex multi-harmonic source power supply network, the linear load simply consumes without injecting harmonic power, but Harmonic sources may absorb harmonic power, which is prone to "missing judgment", so "whether to inject harmonic power into the network" cannot be used as the basis for judging harmonic sources

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