Determining Optimal Location and Size of Distributed Generation Resources Considering Harmonic and Protection Coordination Limits

TLDR

The DG penetration level can be limited by harmonic distortion from inverter‑based units and by protection coordination constraints due to fault current variations from synchronous units. The study proposes an optimization problem to maximize distributed generation penetration by selecting types, locations, and sizes of utility‑owned DG units while considering power balance, voltage limits, harmonic distortion, over‑current relay times, and protection coordination constraints. The authors formulate the problem as a nonlinear programming model, test it on an IEEE‑30 bus network with ten load and DG scenarios, and also assess the feasibility of customer‑owned DG installations under power quality and protection coordination constraints. Simulation results demonstrate the effectiveness of the proposed approach, making it an efficient planning tool for utility operators.

Abstract

In this paper, a new optimization problem is proposed to determine the maximum distributed generation (DG) penetration level by optimally selecting types, locations and sizes of utility owned DG units. The DG penetration level could be limited by harmonic distortion because of the nonlinear current injected by inverter-based DG units and also protection coordination constraints because of the variation in fault current caused by synchronous-based DG units. Hence the objective of the proposed problem is to maximize DG penetration level from both types of DG units, taking into account power balance constraints, bus voltage limits, total and individual harmonic distortion limits specified by the IEEE-519 standard, over-current relay operating time limits, and protection coordination constraints. The DG penetration study is formulated as a nonlinear programming (NLP) problem and tested on the IEEE-30 bus looped distribution network with ten load and DG scenarios. Similarly, feasibility assessment of customer owned DG unit installations considering power quality and protection coordination is also studied. Simulation results show the effectiveness of the proposed approach, which can serve as an efficient planning tool for utility operators.