Weak Grid-Induced Stability Problems and Solutions of Distributed Static Compensators with Voltage Droop Support

Abstract

Distributed static compensators (DSTATCOMs) are grid-connected power electronic equipment dedicated to compensating reactive power as well as improving voltage regulation in distribution networks. They eclipse conventional compensation approaches, such as capacitor banks, in terms of flexibility and effectiveness. Despite their identified advantages, STATCOMs with voltage droop are subject to weak grid-induced stability problems, as first revealed by this paper. Specifically, the voltage droop controller that couples the amplitude of point of common coupling (PCC) voltages to the reactive current reference creates a local control loop. Such a loop greatly deteriorates system stability in weak grids, which feature large and variable grid impedances. To address such stability problems, we propose a novel virtual resistance control scheme, which improves system stability through mitigation of local control loop gains in the low-frequency band. Experimental results obtained from a DSTATCOM prototype clearly demonstrate the correctness of stability analysis and the effectiveness of stability improvement.

Centralized Reactive Power Controller for Grid Stability and Voltage Control

“…All the connected loads, generators, shunt reactors and capacitor banks including LCC based HVDC RPC shall be monitored and controlled by the centralized level RPC. This centralized RPC shall control the loads connected to the transmission grid and also control the active power flow from the generators within an allowed margin which shall be set by the operator to control the grid voltage level [28]. Also, this centralized RPC shall connect and disconnect the shunt reactors, capacitor banks which are located at different parts of the grid to keep the grid voltage at different nodes of the region within the specified limits [29].…”

Research on an Adaptive Compound Control Strategy of a Hybrid Compensation System

“…The rapid development of power electronics has led to their increasing popularity and usage in distribution grids, resulting in a significant rise in non-linear loads [1][2][3][4]. These loads generate notable harmonic currents and reactive power losses that have adverse impacts on both power quality and economic operation [5][6][7][8][9]. To address this issue, a hybrid compensation system that combines an Active Power Filter (APF) and a Thyristor Switching Capacitor (TSC) has been utilized [10][11][12].…”