Optimal distributed generation penetration considering relay coordination and power quality requirements

Although the electric energy supply from distributed generation (DG) resources is increasing, these sources also face limitations. Protection and power quality constraints are the most important issues that limit the maximum DG penetration in power systems. Changing the short circuit level due to DGs' presence—especially synchronous‐based (SDG) type—may lead to miscoordination of the protective relays. Also, standard harmonic limits may be violated due to harmonic injection of inverter‐based DGs and non‐linear loads. A protection coordination problem is solved for the basic configuration, and the optimal settings are applied. Then, using a proposed approach and a new objective function, the location, size, and type of DGs are optimized to maximize the DG penetration and the speed of protection system, while reducing power losses. Finally, the protection setting of SDGs is optimized and applied. In these optimizations, the protection coordination constraints and the power quality requirements are considered and met. IEEE 14‐bus system and a real sub‐transmission system are simulated to evaluate the proposed approach and the new objective function. The obtained results show significant power loss reduction and protection speed improvement for different scenarios and case studies.