Dynamic optimal power flow incorporating gas turbine generator unit with compressed natural gas systems

In developing countries, gas infrastructures are not well established yet. Consequently, insufficient gas supply for gas turbine generator unit may occur during peak load hours. Dual firing unit can overcome such limitation by switching the fuel to High Speed Diesel Oil. However, it will significantly increase the operation cost since High Speed Diesel fuel is much more expensive than natural gas. Recently, a compressed natural gas system has been widely used to solve inadequacy of gas supply during peak load hours. This system compresses the remaining natural gas supply from gas provider during off-peak load hours and stores it into gas tubes. The compressed gas is then released to top up gas supply to gas turbine during peak load hours. Thus, the unit can fully operate on gas at both peak and off-peak load hours. As a result, the operation cost will be lower. This paper proposes an approach in optimizing system operation cost of large system, which has gas turbine generator unit with compressed natural gas system. Furthermore, load curtailment and implementation of take or pay energy contract is also included. The problem is formulated as dynamic optimal power flow and solved using quadratic programming. The proposed approach is tested using IEEE 30 bus and Jawa Bali 500 kV. The results show the effectiveness of the approach in optimizing daily gas usage as well as satisfying take or pay energy contract.