A frequency control method for offshore wind power connected to a multi-terminal flexible direct current transmission system

Abstract

The invention discloses a frequency control method of an offshore wind power integration multi-terminal flexible DC transmission system. When a shore-based converter station exits, asynchronous power grid transient frequency deviation drop and wind farm additional pitch angle control are realized through reasonable configuration of the controllers of a converter station in a power grid at a receiver side and through wind farm additional virtual inertia control, and asynchronous power grid steady-state frequency deviation is eliminated eventually. Thus, the frequency characteristic of adjacent asynchronous power grids is improved, and the influence of failure of a converter station on the operation safety and stability of other shore-based asynchronous power grids is reduced. By using the method to analyze the exit of a shore-based converter station of a large-capacity offshore wind farm integration multi-terminal flexible DC transmission system, the designed frequency control strategy can improve the frequency stability of a shore-based AC system.

Description

technical field [0001] The invention belongs to the technical field of power systems, and in particular relates to a frequency control method for connecting offshore wind power to a multi-terminal flexible direct current transmission system. Background technique [0002] In the face of the rapid consumption of fossil energy and the increasingly severe environmental governance, new energy represented by wind power is a key measure to achieve sustainable development of energy and the environment. With the limitation of land resources and wind power resources, and important progress in the development and application of offshore wind power, offshore wind power has become an important direction for the development of wind power. According to the forecast of the European Wind Energy Association, the installed capacity of offshore wind farms in Europe will reach 40GW and 150GW in 2020 and 2030, respectively. In China, the National Energy Administration issued the "National Offsho...

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Problems solved by technology

At present, the literature only focuses on improving the frequency stability of the AC system through the frequency control of the converter station in the case of active power fluctuations in the AC system, but there are few literatures that mention the safety and stability of the AC-DC system when the converter station fails and exits operation. performance impact

When the transmission power of the converter station is large and the inertia of the AC system is small, the outage of the converter station will also have a serious impact on the AC system, especially when the converter station is out of operation, the remaining DC power cannot be converted by the synchronization grid. In the self-consumption scenario of the flow station, how to control the frequency of the offshore wind power and VSC-MTDC system to effectively reduce the impact of the converter station out of operation on the AC system needs to be resolved

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