Voltage Stability Of Distribution System Research Articles

Optimal allocation of Combined DG and DSTATCOM for Improving Voltage Stability and Economical Benefits of Distribution System

In the vertically integrated power sector, the distribution system serves as the link between customers and the transmission network. Different load models, including industrial, residential, and commercial, are taken into account within the distribution systems. The loading pattern of these load models varies with a large range according to the peak hours. During peak load conditions, the voltage magnitude of some nodes exceeds the permissible limit of voltage value. It affects the voltage stability of the distribution system, leading to decreased reliability, heightened power losses, diminished voltage stability, and other safety concerns. Optimal placement of capacitors, applying DGs, using FACTS devices, and Distribution Network reconfigurations are possible to reduce the power loss. This paper focuses on reducing power loss and enhancing the voltage profile and stability of the system. It addresses the technical, economic, and environmental benefits of the distribution system through appropriate placement and sizing of DG and DSTATCOM units in a coordinated manner. The issue is approached as a Multi-Objective Optimization Problem (MOP) and is tackled through the application of the Group Teaching Optimization (GTO) algorithm, an innovative metaheuristic method. A numerical illustration utilizing an IEEE 69-node system is examined, and the simulated outcomes are presented in tabular form. These results are then juxtaposed with findings from comparable methodologies outlined in existing literature.

Optimization of distribution network operating parameters in grid tied microgrid with electric vehicle charging station placement and sizing in the presence of uncertainties

ABSTRACT The power generated by renewable sources is prone to uncertainties which encourages to perform effective modelling to ensure the reliable operation of the grid-connected microgrid (MG) system. This work focuses on the uncertainty modelling of primary sources of solar power, wind power and electric vehicle (EV) load considering three factors battery capacity, state of charge (SoC) and type of EVs charged by employing Monte-Carlo Simulation (MCS) to minimize the distribution system's voltage stability, reliability and power loss (VRP) index. The objective function is tested on the modified IEEE-33 bus distribution system under three diverse scenarios with optimum sizing and placement of RESs and EVCS. To obtain optimal solutions for the proposed problem in a reasonable computation time, modified version of teaching and learning-based optimization (TLBO) and the JAYA algorithm are applied as the rate of convergence is superior to other existing methods in the literature and does not require any precise control parameters. For all the scenarios, it can be seen that the modified JAYA algorithm outperforms TLBO and other existing approaches. The findings of the results reveal the efficacy of uncertainty modelling in a proposed grid-connected DC MG to curtail the VRP index.

Voltage Stability Enhancement Using DSTATCOM Under Contingency Condition

Current scenario is modern existence and distribution system that is loaded heavily. Also, it altered a lot due to marvelous surge on distribution system load, surge in renewable supply group, accumulation of solar power systems by residential, manufacturing patrons and production of bulky rechargeable stations. Study on voltage stability distinguished based on distribution system is increasing demand. At some extent, an unintentional line outage puts the system security and reliability in kept under hazard. In this manuscript, the main focus is working on contingency analysis in standard 15 bus system Radial Distribution System. An algorithm shows that forecast the setting and quantity of capacity reduce the development of voltage stability in distribution system. Then, the proposed method is executed on a standard 15 bus system Radial Distribution System and effects indicates that voltage stability of the system enhanced along execution of above method uses DSTATCOM and it is implemented in MATLAB.

Optimal Operation of Electric Vehicles and Distributed Generation Resources in Smart Grid Considering Load Management

Technology advancement and the global tendency to use renewable energy in distributed generation units in the distribution network have been proposed as sources of energy supply. Despite the complexity of their protection, as well as the operation of distributed generation resources in the distribution network, factors such as improving reliability, increasing production capacity of the distribution network, stabilizing the voltage of the distribution network, reducing peak clipping losses, as well as economic and environmental considerations, have expanded the influence of distributed generation (DG) resources in the distribution network. The location of DG sources and their capacity are the key factors in the effectiveness of distributed generation in the voltage stability of distribution systems. Nowadays, along with the scattered production sources of electric vehicles with the ability to connect to the network, due to having an energy storage system, they are known as valuable resources that can provide various services to the power system. These vehicles can empower the grid or be used as a storage supply source when parked and connected to the grid. This paper introduces and studies a two-stage planning framework for the concurrent management of many electric vehicles and distributed generation resources with private ownership. In the first stage, the aim is to increase the profit of electric vehicles and distributed generation sources; finally, the purpose is to reduce operating costs. The proposed scheduling framework is tested on a distribution network connected to bus 5 of the RBTS sample network. Besides distributed generation sources and electric vehicles, we integrate time-consistent load management into the system. Due to distributed generation sources such as photovoltaic systems and wind turbines and the studied design in the modeling, we use the Taguchi TOAT algorithm to generate and reduce the scenario to ensure the uncertainty in renewable energy. MATLAB software is used to solve the problem and select the optimal answer.

TPCPF: Three-Phase Continuation Power Flow Tool for Voltage Stability Assessment of Distribution Networks With Distributed Energy Resources

This work presents a three-phase unbalanced continuation power flow algorithm for voltage stability assessment of distribution systems with high penetration of distributed energy resources (DERs). Analyzing distribution system voltage stability with DER will allow high penetration of renewable energy necessary for the sustainability goals. The developed algorithm can analyze voltage stability for both the meshed and radial systems and the balanced and unbalanced three-phase distribution systems. The developed tool allows the voltage stability analysis to facilitate the planning, operation, control, and distribution system management. The impact of DER on the voltage stability of several test cases has been analyzed considering constant power (PQ) and regulated-voltage (PV) modes of operation for DER units. Moreover, different voltage stability case studies are presented to demonstrate the impact of unbalance, load increment, and network topology on the maximum loading capacity. Results using the IEEE 13-node feeder, the 18-bus balanced shipboard system, the 13-node CIGRE benchmark system, and the 136-bus redial distribution feeder demonstrate that the developed continuation power flow tool can efficiently perform voltage stability analysis for active distribution systems.

Switching Analysis of Power Distribution Network Including Distributed Generations Using ATP.(Dept.E)

The distributed generation (DG) emerged as an ideal option deals with the growth in electricity demand. With such a new system there is always a chance of some transient disturbances. A transient can be caused by a number of power system switching events or faults such as lightning strikes, short circuits, or equipment failure. The purpose of this work is to identify the best location of DG connection and if the DG should be concentrated in one location or distributed among different location in distribution network as well as identifying the suitable DG penetration level that can be inserted without affecting the distribution system voltage stability or its power quality based on the European technical standard and the Standard for Interconnecting Distributed Resources with Electric Power Systems IEEE-1547 standard. To achieve these goals, a transient simulation is developed for DG energization with different penetration levels and different locations on power distribution network to investigate voltage stability and power quality of the distribution system. The DG can greatly affect the voltage profile, reverse power flow, power quality, and so on. General purpose Alternative Transients Program (ATP) version of Electromagnetic Transient Program (EMTP) is used to accomplish the above goals. IEEE 13 node test feeder distribution system is used in this work.

Dynamic Voltage Stability of Distribution Systems in the Presence of High Penetration of Photovoltaic Plants Using PSS/E Software

The intermittent nature of photovoltaic (PV) generation causes the voltage to fluctuate and may lead to instability, especially, in case of high penetration. In this paper, a methodology is proposed to control the reactive power generation of PV-inverters. The objective is to mitigate the voltage fluctuations at the point of common coupling (PCC) resulted from increasing or decreasing the active power output of PV plants which is dependent on solar radiation level. The generic PV-inverter models developed and recommended by the Renewable Energy Modeling Task Force (REMTF) of the Western Electricity Coordinating Council (WECC) is used to analyze the effect of high PV penetration on the dynamic voltage stability of distribution networks. Then, the tested distribution network with the embedded PV plants is modeled and simulated using PSS/E software. Levels of control that are built-in PV-inverters are tested in the case of normal operation and during disturbances. Comparison results show that the most suitable control methodology in case of disturbances and after fault clearance is the local voltage control. While the plant voltage control with coordinated V/Q control is the most preferable control methodology during normal operation.

DG Allocation in Distribution Networks with Considering of Voltage Stability Improvement and Loss Reduction

The improvement of the line Load-ability (LL) for voltage stability establishes the main criterion for distribution networks. The Distributed Generation (DG) resources play an important role in the supply of active and reactive power loads, bus voltage profiles, and voltage stability in distribution systems. In this paper, a new technique has been proposed for optimization of the location placement and sizing of DGs, considering the Generalized voltage Stability Index (GSI) to determine the maximum load-ability. Also, an analytical method has been applied to infer the effects of DGs on the distribution systems’ characteristics. The study also considers three types of DG modes, which are voltage control mode (PV mode), constant power mode (PQ mode), and also voltage control mode with reactive power constraint (PV mode with VAR constraint). The proposed method is applied to 12-bus, modified 12-bus, 69-bus and 94-bus radial distribution systems.

Analyzing Impact of Distributed PV Generation on Integrated Transmission & Distribution System Voltage Stability—A Graph Trace Analysis Based Approach

The use of a Graph Trace Analysis (GTA)-based power flow for analyzing the voltage stability of integrated Transmission and Distribution (T&D) networks is discussed in the context of distributed Photovoltaic (PV) generation. The voltage stability of lines and the load carrying capability of buses is analyzed at various PV penetration levels. It is shown that as the PV generation levels increase, an increase in the steady state voltage stability of the system is observed. Moreover, within certain regions of stability margin changes, changes in voltage stability margins of transmission lines are shown to be linearly related to changes in the loading of the lines. Two case studies are presented, where one case study involves a model with eight voltage levels and 784,000 nodes. In one case study, a voltage-stability heat map is used to demonstrate the identification of weak lines and buses.

Probabilistic assessment of static voltage stability in distribution systems considering wind generation using catastrophe theory

With increasing penetration of distributed generations, the importance of the voltage stability assessment of distribution networks has been increased. Considering this situation, a probabilistic model is proposed to evaluate the voltage stability of distribution network integrating wind turbine (WT) units. With this intention, a probabilistic voltage stability index (PVSI) of a radial distribution system with wind power generation is presented. This index investigates the probabilistic risk of voltage collapse for all the buses of system considering uncertainty of WTs. Therefore, the most sensitive bus to the voltage collapse can be identified. The problem model is based on the catastrophe theory that can find the bifurcation point of system. Three-point estimation method is employed to calculate the statistical moments of voltage and PVSI of nodes. Moreover, to estimate the cumulative distribution function of output random variables, the Cornish−Fisher series are used. The performance of the probabilistic index is tested on the IEEE 69-bus radial distribution system where different load models are considered. The results demonstrate that the PVSI can accurately predict the voltage instability condition of the system.

Optimal Allocation of Renewable Distributed Generation and Capacitor Banks in Distribution Systems using Salp Swarm Algorithm

Recent advances in power generation technologies using renewable energy resources, changes in utility infrastructure and government policies tend to increase the interest in a renewable-based distributed generation units (DGs) in a distribution system. To obtain reduced power loss, voltage deviation and improved bus voltage stability in distribution systems, it is mandatory to control optimal power flow of both active and reactive power. Therefore, optimal allocation of DGs and CBs plays a vital role in distribution systems performance enhancement. Where optimal allocation of DGs reduce active power loss and optimal allocation of capacitor banks (CBs) improve bus voltages. This paper proposes a salp swarm algorithm (SSA) for optimal allocation of DGs and CBs. The main aim of the proposed algorithm is to attain technical, economic and environmental benefits. The proposed algorithm is based on the salps swarming behavior in oceans when navigating and foraging. To assess the performance of the proposed SSA three different cases considered: optimal allocation of only DGs, only CBs and simultaneous DGs and CBs. The proposed algorithm is tested on IEEE 33 and 69 bus radial distribution systems. The simulated results illustrate the efficiency of the proposed algorithm when compared to other existing optimization algorithms. Also, the proposed algorithm has achieved technical benefits of reduced power loss, voltage deviation, and improved bus voltage stability, the economic benefit of reduced total electrical energy cost and environmental benefit of reduced emissions.

Impact of Semiconductor Devices on Voltage Stability of Distribution System

Highly efficient and reliable semiconductor devices, which processed the electrical power, are very essential for stable and efficient power system. Semiconductors based controllers is a keystone technology in power distribution system. Semiconductor plays a vital role for improvement of voltage stability in power system. This paper principally integrates semiconductor based Flexible Alternating Current Transmission System (FACTS) controller to improve the voltage stability. A Particle Swarm Optimization (PSO) based algorithm is developed to determine optimal location ofsemiconductor based Static Voltage Controller (SVC) for improving the voltage security. The impact of semiconductor based controller with most critical line outage is also evaluated. Authors compare the results with and without controller under different circumstances such as most critical contingency and under normal condition at rated load. Results show that proposed methodology is competent and SVC is one of the most suitable semiconductor based controller.

Distributed generations planning using flower pollination algorithm for enhancing distribution system voltage stability

Abstract Distributed generations (DGs) have been utilized in some electric power networks. Power loss reductions, voltage improvement, increasing reliability, postponement of system upgrading and environmental friendliness are some advantages of DG-unit applications. This paper presents a new optimization approach that employs a flower pollination algorithm (FPA) to determine the optimal DG-unit’s size and location in order to minimize the total system real power loss and improve the system buses voltage. The FPA is a new metaheuristic optimization technique and it is inspired by the reproduction strategy of the flow pollination process of flowering plants. To reveal the validity of the FPA algorithm, IEEE 33-bus, 69-bus and 136-bus radial distribution test systems are examined with different test cases of the objective function using the MATLAB. Furthermore, the results obtained by the proposed FPA algorithm are compared with other metaheuristic optimization techniques such as backtracking search optimization algorithm, artificial bee colony, and selection algorithm. The outcomes verify that the FPA algorithm is efficient, robust, and capable of handling mixed integer nonlinear optimization problems.

Voltage stability improvement of distributed generation

This Paper presents an analysis of voltage stability in distribution systems, in the presence of distributed generation (DG). This paper include Steady state voltage and current and load Flow steady for reduce loss in power distribution system. In this paper included result of Matlab model and MIPower Experiments for voltage stability improvement of Distributed Generation. IN this paper mainly the focus is to minimize the power losses so that the voltage stability of distributed generation improved as a result.

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

Two algorithms for optimal capacitor placement, with a view to enhance voltage stability are introduced. In the analytical algorithm the nodes, whose voltage stability index values are lower than a threshold value, are ranked in ascending order as the candidate nodes for compensation. The additional reactive power compensation to be provided at a node is obtained by solving linearized VSI formula. The maximum compensation at each node is limited to the initial reactive power delivered by the respective node prior to compensation for avoiding over-dimensioning of the capacitor banks. However, capacitor placement based on voltage stability index has proven less than satisfactory and not always indicated the appropriate placement.As an alternative a fuzzy expert system is used for extracting suitability of capacitor location from power loss reduction index and improving the voltage profile within voltage constraints. A combination of fuzzy expert system for capacitor placement and real coded GA for capacitor sizing, with a view to enhance voltage stability is proposed for optimal capacitor placement. The result is enhancement of the overall system stability index and potential achievement of maximum net money savings due to power and energy loss reduction vs. expenditure in capacitors.The overall accuracy and reliability of the proposed Fuzzy-Real Coded GA algorithm has been validated and tested on 33-node radial distribution system. Comparison of obtained results with those in recent publications showed that the Fuzzy-Real Coded GA algorithm is capable of producing high-quality solutions with good performance of convergence, and demonstrated viability.

Enhancement of Voltage Stability in Distribution Systems by Optimal Placement of Distribution Generator

ABSTRACT This article presents a methodology for optimal placement of DG units in distribution networks to guarantee the enhancement of voltage profile, maximize loadability and reduce distribution system losses. The methodology aims to find the configuration, among a set of system components, which meets the desired system reliability requirements, taking into account the stability limits. Results shown in the article indicate that the proposed formulations can be used to determine which are the best buses, where the addition of small distributed generator units can greatly enhance the voltage stability of the whole system and improve power transfer capability by reducing the system power losses. The proposed methodology is tested and compared with the existing distribution system.

Simple and efficient method for steady-state voltage stability assessment of radial distribution systems

Abstract A new static voltage stability index of a radial distribution system is proposed to faithfully evaluate the severity of the loading situation, thereby predicting for voltage instability at definite load value. The proposed index includes different parameters which affect the steady-state voltage stability of distribution systems, therefore it gives accurate results. The maximum value of 1 of that index denotes the point where the system reaches the point of collapse whereas a minimum value of 0 shows the state of no load. The performance of the new index was tested on two radial distribution systems consisting of 33 and 85 buses. Comparison between the results of the new index and those of previous indices showed that the new index yielded reliable results in predicting voltage stability condition of the system. The new index overcomes the problem which faces many previous indices especially as the load approaches the critical point. Analysis of the two-bus equivalents of the test systems under different scenarios is also presented. A new P–Q plane of stability is introduced based on the equation of the proposed index. The active, reactive and apparent power margins are then directly determined from the voltage stability boundary.

Small-Disturbance Voltage Stability of Distribution Systems With Induction Generators

This letter presents an investigation about the small-disturbance voltage stability of distribution systems with induction generators by using time-domain nonlinear dynamic simulations. Results show that the presence of induction generators may decrease the system voltage stability margin. It was verified that at the maximum loading point, if the system loading is increased even more, then the induction generator accelerates to a high speed, becoming unstable and leading the system to a voltage collapse.

On-line Network Reconfiguration for Enhancement of Voltage Stability in Distribution Systems Using Artificial Neural Networks

Network reconfiguration for maximizing voltage stability is the determination of switching-options that maximize voltage stability the most for a particular set of loads on the distribution systems, and is performed by altering the topological structure of distribution feeders. Network reconfiguration for time-varying loads is a complex and extremely nonlinear optimization problem which can be effectively solved by Artificial Neural Networks (ANNs), as ANNs are capable of learning a tremendous variety of pattern mapping relationships without having a priori knowledge of a mathematical function. In this paper a generalized ANN model is proposed for on-line enhancement of voltage stability under varying load conditions. The training sets for the ANN are carefully selected to cover the entire range of input space. For the ANN model, the training data are generated from the Daily Load Curves (DLCs). A 16-bus test system is considered to demonstrate the performance of the developed ANN model. The proposed ANN is trained using Conjugate Gradient Descent Back-propagation Algorithm and tested by applying arbitrary input data generated from DLCs. The test results of the ANN model are found to be the same as that obtained by off-line simulation. The enhancement of voltage stability can be achieved by the proposed method without any additional cost involved for installation of capacitors, tap-changing transformers, and the related switching equipment in the distribution systems. The developed ANN model can be implemented in hardware using the neural chips currently available.

Stability of loadflow techniques for distribution system voltage stability analysis

Loadflow techniques are widely used in the planning and daily operation of power systems including that of the on-line monitoring of distribution system operation. The performance of three loadflow techniques is investigated in their ability to analyse distribution network loadflows. The criterion for voltage instability is presented and the ability of the three loadflow techniques to predict it is discussed.