Hierarchical Control of Stand Alone Microgrid for Peak and off-peak Hours Operation

Abstract

Microgrid faces power quality issues like voltage and frequency unbalance due to its low inertia. The limited generation and heterogeneous load switching results in generation scarcity and hence affect the power quality. The intermittent availability of Renewable Energy Sources (RES) also hampers seamless power transfer. Thus, this paper presents a hierarchical control strategy where the primary control strategy maintains the voltage through a closed-loop inverter control technique and frequency through P-f droop mechanism. The secondary control implements a load management strategy to reduce peak demand and maintain frequency through Demand Side Management (DSM) by scheduling Thermostatic Control Loads (TCLs) and grid-tied electric vehicles. In recent scenarios, the usage of such loads is gaining ground hence scheduling results in balancing generation and demand. The voltage and frequency should be maintained adhere to IEEE 1547.1 by taking utmost priority to the customer’s comfort. The test system comprises of modified IEEE 13 bus system connected with PV, Battery Energy Storage System (BESS), and Diesel Generator (DZ) for emergency purposes. The hierarchical control strategy is advantageous for peak and off-peak loading conditions with drastic load variation.