Unbalanced power adaptive optimization allocation method for multi-end linear system

Abstract

The invention discloses an unbalanced power adaptive optimization allocation method for a multi-end linear system. The method employs a dual-layer control structure comprising a primary sag control layer and a power rebalance optimization layer. The power rebalance optimization layer aims at the unbalance power caused by the frequent fluctuation of a load or new energy, and an equivalent cost expression of a system additional power generation cost caused by the power rebalance is deduced based on a multi-end flexible DC polar coordinate equivalent model comprising a voltage source converter station, a radial multi-end flexible DC common DC reference voltage is introduced, and a novel active power-DC voltage sag curve is designed. The proposed method irons out the defects that the conventional optimization control strongly depends on the high-speed communication and a centralized processing layer. The method can enable the white balance power to be adaptively and economically allocatedunder the normal condition, enables the additional power generation cost of a system to be remarkably reduced, still can maintain the DC voltage stability and power balance under the fault condition,and is remarkable in control effect.

Description

technical field [0001] The invention belongs to the technical field of flexible direct current transmission system control, and relates to a method for self-adaptive optimal distribution of unbalanced power in a multi-terminal flexible direct current system. Background technique [0002] With the emergence of multi-power supply and multi-drop power receiving problems, the multi-terminal direct current transmission system (MMC-MTDC) based on modular multi-level equal voltage source converters (MMC-MTDC) is widely used in large-scale applications due to its high economy and flexible topology. Fields such as long-distance power transmission and new energy grid integration have received extensive attention. The primary goal of the safe and stable operation of MMC-MTDC is to achieve DC voltage stability and active power balance of multi-terminal flexible DC MMC-MTDC through coordinated control. [0003] As far as several common coordinated control methods are concerned, the rese...

AI Technical Summary

Problems solved by technology

[0003] As far as several common coordinated control methods are concerned, the research on combining the traditional DC voltage droop control with the research on economic dispatching problems is still relatively small, and the master-slave control and DC voltage deviation control methods all require a master converter The flow station is used to maintain the stability of the DC voltage, and the reliability of the system operation is relatively low. Once the power of the master station exceeds the limit or quits the operation, the system will not operate normally.

[0004] Most of the research on the economic dispatch problem in coordinated control still relies on the central controller (upper layer) and the centralized communication system to issue instructions to each converter station (lower layer). Such a control method needs to establish a huge communication network to transmit the central controller. and the information between each converter station, which increases the cost and complexity of the whole system

In addition, due to the frequent fluctuation and large randomness of wind power output in the multi-terminal flexible direct connection of wind power, in the existing optimal control method considering the economic dispatching problem, the upper-level dispatching instructions of the converter station need to be changed frequently and issued quickly, and in order to ensure the economical It is necessary to obtain and process global information such as network parameters and power fluctuations in real time, resulting in the disadvantage that the control is highly dependent on high-speed and stable communication systems

Images