Minimizing generator tripping at Lakvijaya Power Station with adaptive islanding operation

Abstract

Sri Lankan power system consists of broad diversity of energy sources including hydropower, coal, petroleum fuels and renewable sources such as wind, solar and biomass. Lakvijaya power station, the largest coal power complex, consisting of 3 units of 300MW generation. Based on recent statistics, Lakvijaya power plant produced 4645 GWh in 2023, which is 29.8% of the total generation [22]. In Lakvijaya Power Station, after isolating a generator unit from the grid due to a protection scheme which occurs outside the plant premises, generating units are configured to switch to fast cut back procedure, in which the generating units are operating on in house loads. However, if the grid is not ready to reconnect within 30 minutes, generating units are switched to uncontrolled complete shutdown. After an uncontrolled shutdown it requires approximately 3- 4 days and with the absence of 900MW of power from the national grid, causes a huge financial and economic losses [15]. In this study, an algorithm is proposed for implementing adaptive islanding operation to ensure continuous operation of Lakvijaya power station during a system collapse. The methodology encompasses of 3 steps. Initially, transmission line configuration is arranged in a matrix form using graph theory and using the Dijkstra algorithm shortest path between frequency controlling generator and Lakvijaya PowerStation is identified while minimizing the Load – Generation gap and the final network path is obtained. After obtaining the network path which represents the island then fed in to the PSSE software to observe the steady state and dynamic stability.