Analyzing the Effect of Mutual Inductance on the Grid Integrated Distributed Energy Sources: A Case Study of KEPCO Distribution Network

Abstract

The intermittent power generation of Distributed Generators (DGs) poses significant chal- lenges to the operation of the power grid. This intermittency, caused by the variable nature of renewable energy sources like solar and wind, leads to power flow imbalances and voltage fluctuations. Consequently, a thorough analysis of DGs integration, considering network contingencies, overloading concerns, and the thermal limits of substations, is essential for effective planning and managing the power grid to ensure seamless operation. Mutual Inductance (MI) analysis of distribution lines is essential for comprehending the behavior of the lines, loads, and DGs, as well as ensuring accurate modeling of the Distribution Network (DN). It enables the study of how changing currents in one conductor can induce voltages in nearby conductors, providing valuable insights for effective management and control of the distribution system. While the Korea Electric Power Corporation (KEPCO) currently does not emphasize mutual inductance-based power flow analysis, incorporating such analysis could provide valuable technical insights into the behavior of the power system, thereby potentially enhancing its operational efficiency and performance. In this paper, we analyzed the impact of MI on the DN and formulated the power flow problem. We calculated line impedance by taking into account the configuration of the overhead distribution line, the type of conductor used, and the frequency of the DN. Moreover, we developed a mathematical formulation, based on the backward-forward sweep power flow mechanism, to model polynomial ZIP loads and DGs, while considering both with and without MI cases. The proposed model is utilized with the backward-forward sweep power flow algorithm and applied to two case studies: the IEEE 34 bus test feeder and the KEPCO DN. The simulation results are evaluated by analyzing the voltage profile, system losses, voltage improvement, violations of nominal voltage limits, and voltage sensitivity, considering the temporal and spatial effects of loads and DGs inductions.

Keywords

• Mutual inductance
• load modeling
• power flow
• bidirectional backward-forward power flow
• voltage sensitivity analysis
• distribution networks