Multi-harmonic-source harmonic responsibility quantification method for multi-direct-current feed-in full-cable power supply area

Abstract

The invention discloses a multi-harmonic-source harmonic responsibility quantification method for a multi-direct-current feed-in full-cable power supply area, which is used for analyzing the harmonic responsibility quantification problem of a multi-direct-current feed-in urban power grid and considering the problems of harmonic amplification, resonance and the like caused by the fact that the ground capacitance of a cable is relatively large and inductance-capacitance coupling is easy to occur between the cable and an induced element in the power grid. An improved independent component method is provided by using the sparsity of a hybrid matrix in a multi-harmonic-source responsibility quantification model, and the harmonic responsibility of each dominant harmonic source is analyzed for a bus with relatively high harmonic voltage content in a multi-direct-current feed-in urban power grid. Taking a high-proportion DC feed-in urban power grid containing four converter stations as an example, the correctness and practicability of the proposed method are verified.

Description

technical field [0001] The invention relates to the field of harmonic responsibility quantification of multi-harmonic sources in power quality technology, and in particular to a method for quantifying harmonic responsibilities of multi-harmonic sources in multi-direct current feed-in full cable power supply areas. Background technique [0002] Urban power grid is a global power system including transmission network and multi-voltage level distribution network, which has the characteristics of large number of harmonic sources, high cable coverage, and complex load types. The feed-in of multiple DC transmission systems makes the harmonic source of urban power grid more complicated. On the other hand, the network, source and load structure in the urban power grid has also undergone great changes. The distributed power supply on the grid side has surged, the cable coverage has continued to increase, and power electronics on the load side have become more and more common. With t...

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Problems solved by technology

[0003] The harm of harmonics to the power system is mainly manifested as: 1) The motor generates additional power loss and heat, thereby reducing the operating efficiency of the motor and shortening the service life of the motor

2) Increase the loss of transformer and power grid

As a result, the system cannot operate at full capacity, reducing the operating efficiency of system equipment and shortening the service life of equipment

3) Cause the resonance or harmonic current amplification of the reactive power compensation capacitor bank, resulting in damage to the capacitor due to overcurrent or overvoltage, causing overload or overvoltage breakdown of the power cable

4) Interfering with the normal operation of relay protection devices, automatic control devices and computers based on negative sequence (fundamental wave) quantities in the power system, causing equipment malfunctions

5) Affect the accuracy of measuring and measuring instruments

6) The flow of harmonic current on the high-voltage overhead line not only increases the line loss, but also causes interference to adjacent communication lines, and in extreme cases threatens the safety of communication equipment and personnel

[0005] In addition, the cable rate of the urban power grid is relatively high. Compared with the overhead line, the cable has a larger capacitance to the ground, which is easy to cause inductive-capacitance coupling in the power grid, which affects the conduction characteristics of harmonics, and even leads to harmonic amplification and resonance.

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