A method to improve DC transmission capacity under DC fault steady-state voltage constraints

Abstract

The invention provides a method for improving the direct current transmission capacity of a direct current fault steady-state voltage constraint. The method comprises steps of step 1, acquiring a direct current transmission power value P1 according to a steady-state voltage fluctuating value deltaV, a safety control generator tripping strategy and a direct current reactive swapping control threshold value of a power grid; step 2, if a direct current sending requirement power P is greater than P1, performing optimization and adjustment on the direct current reactive swapping control threshold value; step 3, acquiring a direct current transmission power value P2 of the power grid with the adjusted direct current reactive swapping control threshold value, and if P is greater than P2, performing combined tripping operation on a no-load circuit and a low voltage capacitor of the power grid; step 4, acquiring a direct current transmission power value P3 of the power grid after being subjected to combined tripping operation, and if P is greater than P3, performing direct current operation according to the direct current transmission power value P3. Compared with the prior art, the method for improving the direct current transmission capacity of the direct current fault steady-state voltage constraint provided by the invention can be used for increasing the electricity generating efficiency of a direct current matched power plant, reducing the short power supply in the peak period in a direct current receiving end area, and greatly improving the extra-high voltage direct current transmission capacity.

Description

technical field [0001] The invention relates to a method for improving direct current power transmission capacity, in particular to a method for improving direct current power transmission capacity constrained by DC fault steady-state voltage. Background technique [0002] Southwest my country is rich in energy resources. The Xiangjiaba, Jinping, Xiluodu, Xiaowan and other hydropower stations under construction are densely located and have huge capacity. The total scale greatly exceeds the installed capacity of the Three Gorges Hydropower Station. In order to solve the problem of power transmission in this area, since 2010, State Grid Corporation and China Southern Power Grid Corporation have successively built several ±800kV UHV DC projects with the highest voltage level in the world, including Fufeng, Jinsu, Yunguang, and Nuozhadu. Send large amounts of clean electricity to remote load centers. However, due to the large capacity of UHVDC transmission and the complex inter...

AI Technical Summary

Problems solved by technology

Especially in the transition period after the UHV DC is put into operation, the UHV DC supporting power plant has not yet been fully put into operation, and a large amount of power needs to be organized from the remote power grid, which leads to heavy power flow in the near-area UHV DC power grid.

When the UHVDC DC blockage occurs and the shutdown measures are taken, the power flow level of the UHVDC near-area grid will become lighter, which will cause large fluctuations in the steady-state voltage of the UHVDC converter station near the grid, and even voltage limit violations. Become a major factor restricting the transmission capacity of UHVDC in the initial stage of operation

[0003] Before the UHV DC was put into operation, the conventional DC transmission capacity operating in the power grid was more than half smaller than that of the UHV DC, and most of them were located in areas with strong grid structures. Therefore, the steady-state voltage fluctuation amplitude after the conventional DC block was small, Not a factor constraining DC transmission capacity

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