Control method for maximum transmission power of hybrid double-feed-in direct current power transmission system

Abstract

The invention provides a control method for maximum transmission power of a hybrid double-feed-in direct current power transmission system, which belongs to the field of hybrid direct current power transmission control of an electric power system. According to the method, firstly, a double-feed-in direct current power transmission system model is established, a per-unit value of the hybrid double-feed-in direct current power transmission system is selected and rated operating condition parameters are determined, and the model is solved. Through utilization of a linear relation between a voltage at an alternating current bus of a flexible direct current transmission VSC system and a current flowing from a VSC system converter station to the alternating current bus and equivalent impedance of a tradition direct current power transmission LCC side receiving end grid, two parameters are subjected to linear combination to obtain a virtual point voltage, and through fixed virtual point voltage control of a PI link, the VSC system automatically adjusts the output power for a change of the equivalent impedance of the LCC side receiving end grid, so that the hybrid double-feed-in direct current power transmission system outputs the maximum power under the strength of the receiving end grid. The method has the characteristics of reducing the control difficulty and improving the power transmission capability of the hybrid double-feed-in direct current power transmission system under the same strength of the receiving end grid.

Description

technical field [0001] The invention proposes a method for controlling the maximum transmission power of a hybrid double-feed direct current transmission system, which belongs to the field of hybrid direct current transmission control of electric power systems. Background technique [0002] Traditional direct current transmission (LCC-HVDC, hereinafter referred to as LCC) has become an important way for long-distance power transmission in my country, relying on its advantages such as low energy loss in long-distance transmission and the interconnection between various AC systems. However, LCC-HVDC has the disadvantages of easy commutation failure, the need for certain reactive power compensation, and the inability to transmit power to the weak AC grid at the receiving end. [0003] Flexible direct current transmission (VSC-HVDC, hereinafter referred to as VSC) has the advantages of independent adjustable reactive power and active power, can supply power to weak AC grids, and...

AI Technical Summary

Problems solved by technology

However, at present, there is a lack of systematic analysis and research on the maximum transmission power of the hybrid double-infeed DC transmission system in a steady state, especially how to make the hybrid DC system always operate at the state of maximum power transmission, and there is still a lack of corresponding control strategies

Existing studies on the power transmission capability of hybrid double-infeed HVDC transmission systems need to be analyzed on the basis of knowing the specific value of the equivalent impedance of the receiving-end grid, but it is impossible to obtain the equivalent impedance of the receiving-end grid in real time and accurately in actual engineering value, especially when the strength of the power grid at the receiving end changes, so it is difficult to meet the engineering requirements

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