Method for analyzing operation characteristics of rectifying station connected with alternating current systems with different intensities

Abstract

The invention discloses a method for analyzing operation characteristics of a rectifying station connected with alternating current systems with different intensities in the technical field of high-voltage and direct-current transmission operation and control. The method comprises the first step of establishing a simplified model in which an alternating current system is interactive with a direct current system and introducing the short-circuit ratio concept to represent the intensities of the alternating current systems, the second step of establishing a mathematic model of the alternating current system and the direct current system and initializing variables in the mathematic model, the third step of solving an equation set obtained in the second step to obtain the operation characteristics of the rectifying station connected to the alternating current systems with different intensities. The simple equivalence is carried out on the alternating current systems through the Thevenin equivalent method, the relation between the short-circuit ratio representing the intensities of the alternating current systems and the equivalent impedance module value is established, the intensities of the alternating current systems can be conveniently modified, and an operation characteristic curve of the rectifying station connected to the alternating current systems with different intensities is obtained by solving the equation set describing the operation characteristics of the rectifying station. A new idea is provided for studying the transmission capability and the stability of a direct current power transmission system.

Description

technical field [0001] The invention belongs to the technical field of power system operation and control, and in particular relates to an analysis method for the operation characteristics of a rectifier station connected to different strength AC systems. Background technique [0002] With the development of DC transmission technology in China and the implementation of the strategy of "power transmission from west to east, national networking", DC projects are playing an increasingly important role in my country's power transmission. HVDC transmission has the advantages of economic flexibility and strong controllability, and has great advantages in large-capacity and long-distance transmission. However, in terms of transmission capacity, the DC transmission system is limited, and the decisive factor is the connected AC system. Strength of. [0003] In the existing research, the division standard of AC system strength is based on the size of its short-circuit ratio (SCR), th...

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Problems solved by technology

[0004] Compared with the receiving-end system, the sending-end power grid is basically composed of several giant power stations and rectifier stations connected to form a multi-DC sending system. The power supply form is single and the grid structure is weak.

Faults such as short-circuit of the AC line at the sending end and out-of-operation of large-capacity generators will affect the multi-DC system. The fluctuation of active power in the DC system directly affects the consumption of reactive power. The frequency stability and voltage stability of the sending-end system are facing severe challenges. At the same time, it will have a greater impact on the receiving end system, which in turn will have a greater impact on the AC system

[0005] Current studies believe that DC transmission has more prominent requirements on AC system strength during inverter operation. Therefore, most of them use inverter stations as the research object to analyze the transmission capacity and stability of DC transmission systems, and almost no theoretical analysis has been done on the connection between different systems. Intensity of the operating characteristics of the rectifier station

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