Optimal capacitor placement for enhancing voltage stability in distribution systems using analytical algorithm and Fuzzy-Real Coded GA

This paper presents a new methodology for optimal capacitor placement problem in Radial Distribution System (RDS) in order to reduce the total power losses, to improve the voltage profile, to enhance voltage stability, and to achieve more energy savings. The main contribution of this paper is (i) fuzzy expert system (FES) is used to find the optimal locations for capacitor placement, (ii) A novel power loss sensitivity method is applied to determine the optimal capacitor size, (iii) Impact of capacitor placement on the system performance of the radial distribution systems is evaluated in terms of voltage profile, power losses, energy savings & voltage stability index (VSI), (iv) the annual cost of energy loss, total annual cost and net savings. The combined fuzzy & novel power loss sensitivity method is implemented on Existing rural 15 bus system and standard IEEE-34 bus distribution system, and the results are compared with an existing PSO method and Fuzzy-Harmony search algorithm (HSA).

The problem of capacitor placement on a radial distribution system is formulated and a solution algorithm is proposed. The location, type, and size of capacitors, voltage constraints, and load variations are considered. The objective of capacitor placement is peak power and energy loss reduction, taking into account the cost of the capacitors. The problem is formulated as a mixed integer programming problem. The power flows in the system are explicitly represented, and the voltage constraints are incorporated. A solution method has been implemented that decomposes the problem into a master problem and a slave problem. The master problem is used to determine the location of the capacitors. The slave problem is used by the master problem to determine the type and size of the capacitors placed on the system. In solving the slave problem, and efficient phase I-phase II algorithm is used.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Voltage stability is an important issue in power system operation. Flexible AC transmission systems, so-called FACTS devices, help to improve voltage stability and minimize real power losses. The effectiveness of FACTS devices depend on their proper location and rating. This paper presents a method, based on line flow sensitivity factors such as bus voltage stability index and line voltage stability index, to find suitable locations of multi-type FACTS devices. Also this paper proposes an application of particle swarm optimization (PSO) and harmony search algorithm (HSA) in optimizing the rating of FACTS devices. The proposed approaches are evaluated with three different objective functions namely, minimization of real power loss, improvement of voltage profile and enhancement of voltage stability. The performance of proposed methods is analyzed on IEEE 14 bus system by implementing FACTS devices such as static var compensator (SVC), thyristor controlled series capacitor (TCSC) and unified power flow controller (UPFC).The analysis shows that there is a reduction in real power loss and improvement in voltage stability and voltage profile of the system after employing FACTS devices. It also shows that both real power loss and bus voltage stability index (BVSI) have been reduced more with FACTS ratings obtained from PSO than with that from HSA.

In order to increase the voltage profile and to reduce power loss in the distribution system shunt capacitors are to be installed at suitable locations in a large distribution system. When we place the capacitors optimally we will get some benefits. Placing a capacitor in a Electrical distribution system involves various factors like maximizing energy and peak power loss reduction by installing a capacitor. Location of nodes where the capacitor should be placed is decided by fuzzy expert system by incorporating a set of rules into it, Candidate nodes should be found for capacitor placement using fuzzy system. The objective function includes cost of power loss, energy loss and capacitor banks. Constraints include voltage limits, number and location of installed capacitors. Loss sensitivity factors are used to select the candidate location for capacitor placement. The proposed method is applied to 12 bus and 34 bus radial distribution system. Results show robustness of proposed method in solving this difficult task.

The problem of capacitor allocation in electric distribution systems involves maximizing energy and peak power (demand) loss reductions by means of capacitor installations. This paper presents a novel approach using approximate reasoning to determine suitable candidate nodes in a distribution system for capacitor placement. Voltages and power loss reduction indices of distribution system nodes are modeled by fuzzy membership functions. A fuzzy expert system (FES) containing a set of heuristic rules is then used to determine the capacitor placement suitability of each node in the distribution system. Capacitors are placed on the nodes with the highest suitability. Simulation results show the advantages of this approach over previous capacitor placement algorithms.

Many power system operators and planners are facing serious challenges as DG penetration increases into the distribution networks. The situation is even more critical if the DG is not properly sited as such can lead to an increased power losses and instability of the network. Most objectives have centered on minimization of only real power loss for the system. In this paper optimal sizing of DG considers not only the losses but also voltage stability index value (VSI) so that voltage stability of the network is improved as well. The study also takes into account all the necessary constraints. The objective functions are handled as single multi-objective function, and was subsequently optimized using the proposed Particle swarm optimization (PSO) algorithm. The effectiveness of the algorithm was tested on IEEE 33-Bus test system and result obtained shows that the proposed method gives better DGs outputs and use of VSI values in the optimization has greatly improved the minimum VSI values of the network when compared to situation without it and the power losses did not increase appreciably. The study has also indicated that optimal DG placement has greatly improved voltage profile and voltage stability of the network as well.

Today reliability is a significant boundary in Electrical industry to accomplish high security and ampleness of the system. There are three significant boundaries required to present in reliability analysis viz client composite damage function, average load and failure rate. The vast majority of the intelligent techniques incorporate capacitor cost and reserve funds because of decrease in power through loss. In this research work notwithstanding capacitor cost and advantages because of power loss, reliability cost is likewise included. This paper introduces the novel method for failure rate using thermal loading and life expectancy of transformer and overhead transmission line. Modified failure rate is applied to calculate reliability cost and hence accordingly objective function is calculated. Particle swarm optimization (PSO) is used as an intelligent tool to find the optimal locations and capacitor sizing using dot net framework based software. Before applying PSO tool, IEEE 30 bus system is passed through ETAP load flow study. Load flow data is processed through optimal capacitor placement (OCP) module designed in developed novel software. This paper focuses on OCP for reliability enhancement in voltage constraint while applying objectives to PSO tool. Results are used for comparison of voltage profile, power factor improvement, loss reduction, capacity release and objective cost reduction in OCP.

This study mentions the problem of determining optimal placements and sizes for capacitor banks by comparing different schemes that allow implemented buses at both high and low voltage side, only high voltage side or low voltage side of transformers in distribution systems. Criterions evaluated for each scheme are active and reactive power losses in whole system, voltage value at all buses, installation and operation cost and accumulative profit saving. Standard with and without transformer branches in distribution systems and Newton-Raphson method are introduced to make clear about the way to analyze power flows in whole system. Optimal placements and sizes for capacitor banks are determined by using a proposed algorithm and optimal capacitor placement tool in ETAP software. Simulation results can help to show the comparisons, evaluations and make decision about optimal capacitor placements and sizes. The contribution shows the best scheme that install capacitors at low voltage side of transformers because it has the lowest implemented capacity, highest economic factors while voltage quality is always in allowable range. Achieved results can be applied in any distribution system, help managers have overall review and decide optimal placements and sizes for capacitor banks. Keywords: Capacitor bank, OCP Tool, ETAP software, Optimal placement, Optimal size, Voltage quality, Optimal cost.

A tool for voltage stability and optimization (VS&OP) in radial distribution systems using matlab graphical user interface (GUI)

Capacitors have been installed in distribution systems for improving power factor, improving the voltage profile, increasing the power flow through the transformers and cables and reduction of power losses. A lot of research has been done in this regard. In this work, we propose to install capacitors in a future smart grid where Demand Side Management (DSM) can be utilized as a resource in system planning. With DSM in action, system planners need not take into account the peak load, but a lesser fraction of the same, reducing the costs involved. In this way, we can defer the investments for later. There will be reduced power losses and a better voltage profile in a DSM enabled smart grid and placing capacitors in such a grid will reduce the costs incurred. Reliability evaluation considering reactive power source failures is also performed in the normal system and the one where DSM is in operation. We take a 10 bus radial distribution system and see that DSM reduces the capacitor placement cost and also improves system reliability.

Objectives: The main objective of the proposed investigation is to enhance the voltage stability of Radial Distribution System (RDS). It is achieved by proper allocation between combined Electric Vehicle Charging Stations (EVCSs) and Distributed Generators (DGs) in RDS. Here, three objective functions such as Real Power loss, Average Voltage Devotion Index (AVDI) and Voltage Stability Index (VSI) are considered. Methods: The multi-objective optimization problem is implemented using a novel and an effective Pelican Optimization Algorithm (POA) to attain the best compromised solutions. POA is a nature inspired parameter less optimization tool and it is well suited for solution of complex, non-linear voltage stability problem. It determines the most excellent site and size of the EVCSs and DG units. The control parameter of POA considered are population size as 40, the number of variables as 8 and the maximum number of iterations as 100. MATLAB 14.0 platform is utilized for the projected problem. Findings: The bench mark test system of IEEE-33 node system is considered to authenticate the presentation of planned POA methodology. The outcomes such as minimized power loss and AVDI, improved voltage at each bus and VSI are presented. The percentage of loss reduction 39.30% is enhanced, when compared with the base case approach and 5.42 % more improved than the other existing methods like TLBO and HHO approaches. Similarly, the VSI 24.96 % is improved, when compared with the base case method and 1.58 % better than the other obtainable methods. Novelty: The POA is a newly urbanized and well-designed optimization algorithm. It efficiently reaches the global optimal solutions with less time duration. The comparative study with the existing algorithm of TLBO and HHO is considered to prove the performance of Projected POA approach. Keywords: Radial distribution system, Distributed Generators, Electric Vehicles, Charging Stations, Voltage stability, Network loss reduction, Pelican Optimization Algorithm

Optimal Allocation of Combined DG and Capacitor Units for Voltage Stability Enhancement

Renewable energy sources and energy efficiency has emerged as the backbone of sustainable energy solutions in response to the rising tide of concern over energy security and climate change. Efforts to decrease power losses are part of this. This paper investigates the application of the Cheetah optimizer, a modern metaheuristic optimization algorithm, for the optimal sizing and placement of decentralized generation units such as shunt capacitors in radial distribution networks. The primary objectives are to minimize power losses and enhance voltage profiles under varying load conditions. Unlike conventional methods, Cheetah Optimizer employs three innovative strategies with different randomization techniques to achieve a superior balance between exploration and exploitation. The algorithm's performance is validated on the IEEE 33-bus and IEEE 69-bus distribution test systems. This investigation primarily adds value by applying the methodology to the Adrar electricity distribution network in southern Algeria, demonstrating the effectiveness of these methodologies in real-world systems. Comparative analysis demonstrates that the proposed approach achieves significant improvements in loss reduction and voltage stability compared to state-of-the-art algorithms. Key findings indicate that the Cheetah optimizer delivers robust performance across different network scenarios, with a reduction in power losses by up to 37.34 % and 66.11 % on test systems and enhanced voltage stability by increasing the minimum voltage to permissible levels. Sensitivity analysis further confirms the algorithm’s reliability under varying parameter settings. These results underscore the potential of the proposed approach for real-world implementation in optimizing distribution networks.

Shunt capacitors installation in distribution systems requires optimal placement and sizing. More harmonics are being injected into distribution systems. Adding shunt capacitors may lead to high distortion levels. The capacitor placement and sizing problem is a nonlinear integer optimization problem, with locations and ratings of shunt capacitors being discrete values. The goal is to minimize the overall cost of the total real power loss and that of shunt capacitors while satisfying operating and power quality constraints. This paper proposes to solve the problem using particle swarm optimization (PSO). A discrete version of PSO is combined with a radial distribution power flow algorithm (RDPF) to form a hybrid PSO algorithm (HPSO). The former is employed as a global optimizer to find the global optimal solution, while the latter is used to calculate the objective function and to verify bus voltage limits. To include the presence of harmonics, the developed HPSO was integrated with a harmonic power flow algorithm (HPF). The proposed (HPSO-HPF)-based approach is tested on an IEEE 13-bus radial distribution system (13-Bus-RDS). The findings clearly demonstrate the necessity of including harmonics in optimal capacitor placement and sizing to avoid any possible problems associated with harmonics.

The distribution system is the final link between bulk power system and consumer end. A distinctive load flow solution method is used for analysis of the load flow of radial and weakly meshed network based on Kirchhoff’s Current Law (KCL) and KVL. This method has excellent convergence characteristics for both radial as well as weakly meshed structure and is based on bus injection to branch current and branch-current to bus-voltage matrix. The main contribution of the paper is: (i) an analysis has been carried out for a weekly mesh network considering number of loops addition and its impact on the losses, kW and kVAr requirements from a system, and voltage profile, (ii) different load models, realistic ZIP load model and load growth impact on losses, voltage profile, kVA and kVAr requirements, (iii) impact of addition of loops on losses, voltage profile, kVA and kVAr requirements from substation, and (iv) comparison of system performance with radial distribution system. Voltage stability is a major concern in planning and operation of power systems. This paper also includes identifying the closeness critical bus which is the most sensitive to the voltage collapse in radial distribution networks. Node having minimum value of voltage stability index is the most sensitive node. Voltage stability index values are computed for meshed network with number of loops added in the system. The results have been obtained for IEEE 33 and 69 bus test system. The results have also been obtained for radial distribution system for comparison.