Efficient framework for integrating distributed generation and capacitor banks considering simultaneous grid-connected and islanded distribution network operations

Abstract

In literature, for the planning problem of simultaneous distributed generation (DG) and shunt capacitor banks (SCB) allocation in radial distribution networks (RDNs), researchers have focused mainly on the real power loss reduction and ignored the benefits of reactive power loss minimization, which might not distribute DGs and SCBs at the desirable locations. In addition, a variety of metaheuristic optimization techniques have been employed in literature whose implementation involves either the number of phases or tuning of certain algorithm-specific parameters. In contrast, the Jaya algorithm (JA) is a simple and efficient single-phase optimization algorithm that is free from any parameter tuning. However, the JA also suffers from inadequacies of population diversity and premature convergence; therefore, require a mechanism to overcome these deficiencies. Furthermore, past studies conducted for the islanded networks have followed the approach of isolated operation and did not consider the power supply-demand imbalance condition, which will result allocation of oversized DGs and SCBs. Considering these facts, this research work proposes a two-stage planning approach for the efficient utilization of DGs and SCBs for the simultaneous grid-connected and islanded operations of the RDNs. The first stage determines the optimal installation locations and capacities of DGs and SCBs, and operating power factor of DGs using an improved variant of the JA (IJaya) to minimize the total power loss and voltage deviation during the gridconnected operation. For the proposed IJaya, a dynamic weight parameter based grid-search mechanism has been introduced to mitigate the problem of premature convergence and population diversity in JA. The performance of the IJaya was evaluated using the IEEE 33-bus and 69-bus RDNs. A comparative analysis with existing optimization methods reveals that the IJaya achieves up to 38.84% more reduction in power losses and 3.26% more voltage improvement. In the later part of the study, a methodology concerning the efficient and maximum utilization of the installed DG-SCB capacity in the islanded RDN under power imbalance conditions has been proposed. For that, a multiobjective minimization function incorporating the total power loss and under-utilization of available DG-SCB capacity has been established. To minimize the proposed function, an iterative analytical approach has been proposed to tune the source power factor. The results showed that the underutilization of available DG-SCB capacity varies up to 15.83% for the power factors ranging from 0.8 to 0.93. Expectedly, the proposed study will assist the utility companies to efficiently operate their distribution systems and to design effective energy management schemes for the customers.