A coordination control strategy for power quality enhancement of an active distribution network

Abstract

Integration of power electronics-based converter-interfaced distributed generators (DGs) into the existing power systems have created several power quality related challenges. These challenges include reduced voltage rigidness at the point of common coupling (PCC), total harmonic distortion (THD), lack of inertial response and power imbalance due to unconsumed power from DGs. To address these challenges, this paper proposes a coordination control strategy which has two major objectives: (1) to regulate the apparent impedance at the PCC of the active distribution network (ADN) using coordination of DGs; (2) to use active and reactive power of battery energy storage system (BESS) for transient suppression at PCC and reactive power for power factor improvement of DGs. The proposed control strategy is applied to an ADN based on a 7 - bus test system. This study confirms that the unique method of regulating the apparent impedance of PCC using active and reactive power coordination of DGs significantly improves the power quality at the PCC of ADN. For instance, using the proposed method, the percentage overshoot (%OS)of active and reactive power injection at PCC of ADN was reduced up to 19.55% and 12.8%, respectively. Similarly, the THD of the grid current reduced from 4.71% to 2.85%.

Keywords

• Active distribution network (ADN)
• Coordination control strategy
• Virtual synchronous generator (VSG)
• Hierarchical control system
• PCC regulation