A power flow calculation method for bipolar flexible HVDC transmission system

Abstract

The invention discloses a method for calculating the power flow of a bipolar flexible direct current transmission system. First, an initial value of positive active power is given, and when calculating, the power flow is first calculated for the positive network, and the initial value of the active power of the negative node is updated according to the calculation result. The negative network performs power flow calculation, and updates the active power of each positive node according to the negative active power obtained by the power flow calculation. After repeated iterative updates, the voltage corrections of the positive and negative nodes reach the convergence condition. The invention has universality for different multi-terminal DC coordinated control strategies and DC networks with different positive and negative topological structures, and can truly and accurately reflect the power flow distribution of the true bipolar system; the method is based on the node current relationship, and selects the initial value of the voltage. It is insensitive and can achieve the same predetermined calculation accuracy of power flow through fewer iterations, and is more suitable for power flow calculation of multi-terminal flexible DC network systems in engineering.

Description

technical field [0001] The invention belongs to the field of flexible direct current power transmission, and relates to a power flow calculation method of a bipolar flexible direct current power transmission system. Background technique [0002] With the continuous development of renewable energy and the needs of current grid technology upgrades, the future development direction of flexible DC grids will focus on large-scale wind power transmission, regional grid interconnection, and power transmission to urban load centers. The flexible DC transmission system will show the following characteristics: [0003] (1) The flexible DC transmission system is developing towards higher voltage levels and larger transmission capacity, the flexible and reliable true bipolar transmission system is developed and applied, and the power grid operation mode is more complicated; (2) The voltage source converter is conducive to the formation of parallel connection type multi-terminal DC tran...

AI Technical Summary

Problems solved by technology

Due to the current correlation between poles, the power flow calculation method for unipolar networks cannot be directly applied to true bipolar systems

The current power flow algorithm has its limitations. It is only suitable for the power flow calculation of unipolar networks or symmetrical bipolar networks. It can only deal with a limited number of control methods, such as pure active control and simple droop control methods. Bipolar DC transmission system, which obviously cannot meet the needs of the rapidly developing DC grid

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