Optimal inverter based distributed generation units control strategy to improve voltage profiles in unbalanced distribution networks

Recently, the penetration of distributed generation (DG) at distribution level has grown significantly. Unfortunately, this has brought some unexpected power quality problems such as voltage unbalance. To reduce the voltage quality problems deteriorated by unbalanced features, a transformed multi-objective optimal power flow (OPF) model is built to optimise the active and reactive power outputs of three-phase micro-turbine generator units. A stricter measurement of voltage unbalance definition is employed which can replace the traditional voltage unbalance definition since it is able to hugely increase the computing efficiency. Another constraint model is also proposed considering the zero sequence effects for three phases and four wire parts of the whole system. The performance of the presented OPF models with different constraints has been evaluated by the IEEE 13-node and 123-node test cases. These simulation results demonstrate that by the proposed OPF objective function, the new combination of constraints could be exploited to achieve better network performance.