Battery Energy Storage System for Reducing the Impact of Renewable Energy Sources Penetration on Frequency Regulation

Abstract

Grid losses and carbon impact are reduced by integrating renewable energy sources (wind and photovoltaic) into electricity networks. The intermittent nature of RES, however, greatly diminishes system inertia, which has an impact on the system's ability to dampen and modulate primary frequency regulation. Increased PV penetration may result in induced frequency oscillations that may go against grid operating standards and jeopardize the grid's stability and security. In this thesis, to decrease frequency oscillation by improving primary frequency controllability in accordance with grid code and enable more PV penetration, a Battery Energy Storage System (BESS) with droop control is suggested. The primary idea of BESS control is to mimic the governor's drooping behavior found in conventional generators. Fossil fuel based conventional producing unit replacement and the consequences of PV integration at various level with line & load contingencies is investigated. The optimal Sizing and location is also achieved through scenario and comparative performance analysis in this research. Theoretically sizing of BESS is done using inertia constant and droop control for 150 MW replacement of conventional generation with PV, 75 MW sizing of BESS is obtained. When a 100 MW of PV is penetrated with temporary and permanent line outage and heavy load, it is observed that frequency of grid is violated i.e. the frequency deviation of G1 & G2 are extremely oscillatory and exceed the required grid limit by 1.0204 (51.02 Hz; G1) and 1.0246pu (51.23 Hz; G2) respectively. With the addition of 50 MW BESS at bus 7 of IEEE 9 bus system, the frequency of G1 and G2 are under NEM 2% grid criteria i.e. 50.365 Hz & 50.487 respectively. Also for IEEE 14 bus system frequency rise violating the grid criteria with frequency 51.5 Hz with 140 MW PV penetration. The frequency observed with 100 MW size of BESS installed at bus 6 is 0.996 pu i.e. 49.8 Hz for both generators and oscillations are also minimized. RMS/EMT simulations are done for all scenarios in Dig silent power factory environment.