PROJECT TITLE :

Adaptive Droop Control of VSC-MTDC System for Frequency Support and Power Sharing - 2017

ABSTRACT:

This paper proposes an adaptive droop management (ADC) strategy for the voltage source converter (VSC) based multiterminal high voltage direct current (VSC-MTDC) system, that enables the VSC-station to supply frequency regulation for onshore ac grids. A V-I-f characteristic springs to ascertain the connection between the frequency deviation and dc voltage. A VSC-station operating with the V-I-f characteristic is ready to adjust its dc voltage reference autonomously in step with the grid frequency deviation. So, the power flow of the VSC-MTDC system will be redistributed and more power goes to be injected into the adjacent grid of which the frequency deviation exceeds the threshold price. The ADC strategy inherits the advantage of the traditional droop management (TDC) that there is no need for communication system. An ac/dc hybrid system that includes VSC-MTDC system, onshore grids, and offshore wind farms is constructed in DIgSILENT/Powerfactory. Modal analysis and nonlinear simulations are performed to obtain the optimal control parameters and demonstrate the performance of the ADC strategy.