V. Ravikumar Pandi

Dynamic economic load dispatch using hybrid swarm intelligence based harmony search algorithm

This paper presents the hybrid harmony search algorithm with swarm intelligence (HHS) to solve the dynamic economic load dispatch problem. Harmony Search (HS) is a recently developed derivative-free, meta-heuristic optimization algorithm, which draws inspiration from the musical process of searching for a perfect state of harmony. This work is an attempt to hybridize the HS algorithm with the powerful population based algorithm PSO for a better convergence of the proposed algorithm. The main aim of dynamic economic load dispatch problem is to find out the optimal generation schedule of the generators corresponding to the most economical operating point of the system over the considered timing horizon. The proposed algorithm also takes care of different constraints like power balance, ramp rate limits and generation limits by using penalty function method. Simulations were performed over various standard test systems with 5 units, 10 units and 30 units and a comparative study is carried out with other recently reported results. The findings affirmed the robustness and proficiency of the proposed methodology over other existing techniques.

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

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.

Economic Load Dispatch Using Hybrid Swarm Intelligence Based Harmony Search Algorithm

Abstract This article presents a novel stochastic optimization approach to solve the constrained economic load dispatch problem using a hybridization of the harmony search algorithm and particle swarm optimization, named hybrid harmony search based on the swarm intelligence principle. Harmony search is a recently developed derivative-free, meta-heuristic optimization algorithm, which draws inspiration from the musical process of searching for a perfect state of harmony. This work is an attempt to utilize the velocity-based particle updating process from particle swarm optimization in the improvisation process of the harmony search algorithm for a better convergence of the proposed algorithm. The proposed methodology also easily takes care of solving non-convex economic load dispatch problems along with different constraints, such as power balance, ramp rate limits of the generators, and prohibited operating zones. Simulations were performed over four various standard test systems with different numbers of generating units, and a comparative study is carried out with other existing relevant approaches. The findings affirm the robustness and proficiency of the proposed methodology over other existing techniques.

A Protection Coordination Index for Evaluating Distributed Generation Impacts on Protection for Meshed Distribution Systems

Depending on the capacity, type and location, distributed generation (DG) can have an impact on protection coordination of directional over-current relays for looped distribution systems. In this paper, a new index is proposed, “protection coordination index” (PCI), which can serve as an effective measure when planning the protection of meshed distribution systems with DG. A two-phase non-linear programming (NLP) optimization problem is proposed to determine the PCI by optimally calculating variations in the maximum DG penetration level with changes in the protection coordination time interval. Furthermore, the influence of connecting a DG at a certain location on the system PCIs is examined. The presented analysis is tested on the distribution section of the IEEE 14-bus and IEEE 30-bus systems. The PCI can serve as an efficient index for distribution system planners: (i) to determine the best DG candidate locations for utility owned DG and (ii) to evaluate the impact of a customer owned DG, considering distribution system protection.

Improved Harmony Search for Economic Power Dispatch

This paper presents a novel optimization approach using Improved Harmony Search (IHS) algorithm to solve economic power dispatch problem. The proposed methodology easily takes care of different equality and inequality constraints of the power dispatch problem to find the optimal solution. To show its efficiency, the proposed algorithm is applied to single area and multi area system of four area having 16 units with and without Prohibited Operating Zones (POZ). The results are compared with other existing relevant approaches. The result obtained by the proposed method confirmed that the robustness and efficiency of the algorithms over other reported methods.

Distribution System Reconfiguration for Annual Energy Loss Reduction Considering Variable Distributed Generation Profiles

In this paper, a new formulation for distribution system reconfiguration (DSR) is proposed for minimizing the annual energy losses considering the variability in active and reactive power demand and distributed generation (DG) profiles. A fuzzy C-means clustering algorithm is used to obtain representative centroids from annual DG and power demand profiles. The DSR study is formulated as a mixed-integer nonlinear programming optimization problem and tested on a 33-bus and an 84-bus system. The minimization is subject to the power balance, bus voltage, and distribution system radiality constraints. Using this formulation, a single optimum configuration that minimizes annual energy losses is found and shown to be different from the optimum configuration, found in previous literature, which focuses on minimizing power losses at peak or average loads. In addition, the prospective advantages of grid automation on DSR are demonstrated to provide further energy loss reduction by including the possibility of interchanging a predefined number of configurations that minimize annual energy losses.

Dynamic economic load dispatch with wind energy using modified harmony search

The optimisation of fuel cost for short term economic dispatch of thermal generators along with renewable sources like wind generator is considered in this paper. The non-linear constraints considered are power generation limits, reserve limits and ramp rate limits. The optimal dispatch in the presence of the wind generation is obtained using modified harmony search (MHS) algorithm. The wind generator cost model is developed and used in this dynamic economic load dispatch (ELD) problem. The forecasted wind speed is utilised to calculate the average wind power output and this power is included in the economic dispatch model by means of negative load approach. Numerical results for the sample test system having five thermal units, one wind farm and one diesel unit have been presented to demonstrate the performance of the algorithm.

Economic load dispatch using population-variance harmony search algorithm

This paper presents a novel stochastic optimization approach to solve the constrained economic load dispatch (ELD) problem using the harmonic search algorithm (HS). HS is a recently developed derivative-free, meta-heuristic optimization algorithm, which draws inspiration from the musical process of searching for a perfect state of harmony. This work analyses the evolution of the population-variance over successive generations in HS and thereby draws some important conclusions regarding the explorative power of HS. The proposed methodology easily takes care of solving non-convex ELD problems along with different constraints like transmission losses, ramp rate limits of the generators and prohibited operating zones. Simulations were performed over various standard test systems with different number of generating units and a comparative study is carried out with other existing relevant approaches. The findings affirmed the robustness and proficiency of the proposed methodology over other existing techniques.

Economic Load Dispatch Using a Chemotactic Differential Evolution Algorithm

This paper presents a novel stochastic optimization approach to solve constrained economic load dispatch (ELD) problem using Hybrid Bacterial Foraging-Differential Evolution optimization algorithm. In this hybrid approach computational chemotaxis of BFOA, which may also be viewed as a stochastic gradient search, has been coupled with DE type mutation and crossover of the optimization agents. The proposed methodology easily takes care of solving non-convex economic load dispatch problems along with different constraints like transmission losses, dynamic operation constraints (ramp rate limits) and prohibited operating zones. Simulations were performed over various standard test systems with different number of generating units and comparisons are performed with other existing relevant approaches. The findings affirmed the robustness and proficiency of the proposed methodology over other existing techniques.

Allowable DG penetration level considering harmonic distortions

The interconnection of distributed generation (DG) requires careful study with respect to selecting both the best DG location and the size of the DG unit. The DG installation at the distribution level injects harmonics, and thus may lead to significant power quality problems. In this paper, the impact of DG penetration level and DG location is evaluated by considering the power quality limits of IEEE Standard 519–1992. The nonlinear optimization problem is formulated with size of DG being a positive real number to be optimized and solved using particle swarm optimization. The optimization algorithm is integrated with the harmonic power flow algorithm to calculate the values of the system operating point and harmonic components. The formulated approach is tested on an IEEE 18-bus radial distribution system and the results show that the consideration of harmonics during DG interconnection studies is essential to avoid associated power quality problems.