Distribution system reliability enhancement using optimal capacitor placement
ABSTRACT Failure statistics of most utilities indicate that distribution systems make the greatest individual contribution to the unavailability of supply to customers. Optimal capacitor placement in distribution systems has a number of advantages such as reducing losses, improving voltage profile, improving power factor and so on. The conventional objective function of the optimal capacitor placement consists of the total cost of losses and investments. Since capacitors supply reactive loads locally, they improve the load-carrying capability of the lines and therefore play the same role as redundant lines. Thus, optimal capacitor placement can also improve the reliability indices of a distribution system. Therefore two new objective functions are defined here. The first one is defined as the sum of reliability cost and investment cost. The second is defined by adding the reliability cost, cost of losses and investment cost. The latter is a comprehensive objective function which is the resultant of the conventional and reliability-based objective functions. This problem is solved using a particle swarm optimisation-based algorithm. The effectiveness and applicability of the proposed approach are examined using a distribution network.
Article: Optimal Capacitor Placement and Sizing in Distribution Systems with Harmonics Consideration Using a Hybrid Method Based on Simulated Annealing and Generic Algorithm[show abstract] [hide abstract]
ABSTRACT: This paper presents a hybrid algorithm formed by combining the simulated annealing and genetic algorithm (SA-GA) for solving the optimal capacitor placement problem in distribution systems. The objective is to minimize the energy losses in the system while taking the capacitor installation costs into consideration. The capacitor cost is a step-like and, therefore, a non-differentiable function. Load variations, load constraints, operational constraints and constraints on capacitor types and sizes will be all considered in the problem formulation. Models of the distribution system at the fundamental frequency and at harmonic frequencies are established in order to include the non-linear loads into the problem formulation. Nonlinear loads are included to make sure that the resulting harmonic distortion levels are within the acceptable limits. The solution algorithm is implemented into a software package in MATLAB and tested on a 30-bus distribution system containing a loop. Simulation results signify the robustness of the developed SA-GA in finding the optimal locations and ratings of shunt capacitors.Canadian Journal of Electrical and Computer Engineering 01/2012; 37(2):49-55. · 0.24 Impact Factor
Conference Proceeding: Optimisation of Distributed Generation units and shunt capacitors for economic operation of distribution systems[show abstract] [hide abstract]
ABSTRACT: The integration of Distributed Generation (DG) units and shunt capacitors can be considered as an alternative approach for distribution system expansion planning not only to improve power supply quality and reliability, but also to defer major system updates. In this paper, the techno-economic issues of distribution system expansion planning with optimal sizing and siting of DG units and shunt capacitors are addressed. The minimisation of overall investment cost with the integration of DG units and shunt capacitors is assessed with the consideration of supply quality, reliability and energy loss. A new planning methodology by using Particle Swarm Optimisation (PSO) is proposed to minimise the overall cost for optimal sizing and siting of DG units and shunt capacitors. The proposed methodology is tested on a remote 11 kV radial distribution feeder and results are reported.Power Engineering Conference, 2008. AUPEC '08. Australasian Universities; 01/2009