A method for smoothing power fluctuations of flexible DC distribution network

Abstract

The invention provides a method for stabilizing and suppressing the power fluctuation of a flexible direct-current distribution network based on the combined use of an energy storage system and a converter station. The method includes the following steps that: the maximum value f (t) of the active power change of a first cycle is calculated through acquiring the active power PD and active power PS at two ends of the converter station at a time point t, the energy state (SOC) of the energy storage system and the PD of all sampling points in the first cycle before the time point t in real time; the constant power reference value Pref of the constant power converter station is set according to the capacity proportion of the converter station; and the output power PB of the energy storage system is adjusted according to the limiting exceeding situation of the power fluctuation f (t) and the energy state (SOC) of the energy storage system, and the above steps are executed circularly in a system operating cycle T. With the method adopted, under wind electricity, photovoltaic and load quick change conditions, the power fluctuation of the direct-current distribution network can be effectively suppressed and can be controlled to an allowable fluctuation range, and the safe and reliable operation of a system can be ensured.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a method for an energy storage system cooperating with a converter station to stabilize power fluctuations of a flexible direct current distribution network. Background technique [0002] In recent years, with the continuous expansion of city scale and the rapid increase of power load, the requirements for power quality, power supply reliability and transmission capacity of the power grid are also increasing. Flexible DC technology can quickly and independently control active power and reactive power, without increasing the short-circuit capacity of the AC system, without electromagnetic ring network problems, and can be easily connected to distributed power sources, energy storage, electric vehicles and DC loads, so flexible DC Technology has broad prospects for development. [0003] The flexible DC distribution network is connected to the AC grid through the voltage so...

AI Technical Summary

Problems solved by technology

[0005] For different types of distributed power sources such as wind power, solar energy, and energy storage in the DC power distribution network, the active power of AC and DC loads may fluctuate randomly and substantially, resulting in the active power exchanged between the flexible DC converter station and the AC grid. There are large random fluctuations that affect the stable operation of the AC power grid, and a solution is urgently needed

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