Optimization of Placement and Sizing of Distributed Generation and Capacitors for Voltage Stability Improvement

Abstract

Distribution systems form a critical part of the power system by linking the consumer to the transmission system. They are extensive and complex and require adequate planning. One of the main challenges in distribution networks is voltage instability. Voltage instability can be mitigated by distributed generation (DGs) and capacitor placement in distribution networks. The effectiveness of these devices is much dependent on how optimal they are placed and sized within the distribution network. Due to the complexity of distribution networks, planning becomes a complex task. Therefore, new techniques must be developed to assist network planners in optimally placing and sizing capacitors and DGs in distribution networks. In this work, a method for distributed generation and capacitor placement was developed that uses Voltage Stability Index (VSI) to find optimal locations of distributed generation and capacitors and Hybrid Evolution Programming (HEP) to find the optimal sizes of DGs and Capacitors that maximize the voltage stability of a radial distribution network. The test networks used were IEEE 33-bus and IEEE 69-bus radial distribution networks. The voltage profiles and VSIs for the radial distribution systems were compared using optimal sizes obtained from Evolution Programming (EP) and the developed Hybrid Evolution Programming (HEP) Algorithm. The minimum voltage obtained after placing DGs and capacitors using EP in the IEEE 33-bus radial distribution network was 0.9290p.u, whereas the minimum VSI was obtained as 0.7480. When HEP was used, the minimum voltage was 0.9400 p.u. with a VSI of 0.7841. Placing the DGs and Capacitors in the IEEE-69 Bus system resulted in a minimum voltage improvement from 0.8750p.u to 0.9480 p.u., and VSI improvement from 0.5889 to 0.8077. Network modeling and simulations were performed in MATLAB.