Load flow is an important tool used by power engineers for planning, to determine the best operation for a power system and exchange of power between utility companies. In order to have an efficient operating power system, it is necessary to determine which method is suitable and efficient for the system’s load flow analysis. A power flow analysis method may take a long time and therefore prevent achieving an accurate result to a power flow solution because of continuous changes in power demand and generations. This paper presents analysis of the load flow problem in power system planning studies. The numerical methods: Gauss-Seidel, Newton-Raphson and Fast Decoupled methods were compared for a power flow analysis solution. Simulation is carried out using Matlab for test cases of IEEE 9-Bus, IEEE 30-Bus and IEEE 57-Bus system. The simulation results were compared for number of iteration, computational time, tolerance value and convergence. The compared results show that Newton-Raphson is the most reliable method because it has the least number of iteration and converges faster.

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Analysis of the Load Flow Problem in Power System Planning Studies

Load flow, voltage stability & short circuit analyses of a power system are essential for both design and operating stage performance monitoring and to ensure reliable grid operations by adequate protection scheme settings. In this research work, electrical model of a 1240 MW combined cycle power plant (CCPP) is developed on Electrical Transient Analyzer Program (ETAP) and load flow, voltage stability & short circuit analyses are performed. Effect of power grid voltage instability on system buses of the power plant is evaluated. Using load flow analysis that exploits Newton-Raphson algorithm, buses operating at under voltage due to power grid voltage instability are identified and their voltages are improved according to given voltage constraints that are based on buses criticality with respect to loads. On-load tap changers and reactive power compensation are used to improve steady state voltage stability. Optimal position for capacitor banks placement and number of capacitor banks are suggested by using optimal capacitor placement module of ETAP. The results of short circuit analysis are compared with short circuit current values experienced by the power plant sources. Consequently, favorable results have been accomplished through ETAP for all power system analyses.

Load flow, voltage stability & short circuit analyses and remedies for a 1240 MW combined cycle power plant using ETAP

In this paper we have explained about the performance of IEEE-14 bus system by using Mi power technology. In the previous project the load flow analysis and stability analysis was found by using Mi power software. This project shows the short circuit and contingency analysis by using MI power technology. The maximum & minimum real and reactive power limit have been set & the results are obtained. The output result was found more efficient compared to the previous model. All the power system equipments were designed to withstand high efficiency and to withstand worst case condition. The MI power software is the advanced technology in order to improve the load flow analysis, stability analysis, short circuit and contingency analysis. This project explains about the MI power software to which it raises the efficiencies for the calculation of short circuit and contingency analysis. This project explains about the different fault conditions such as symmetrical and unsymmetrical fault analysis in which we are considering about the short circuit analysis. The transient and sub transient components are to be found and the system leads to the stable condition.

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Short Circuit and Contingency Analysis Implementation for IEEE-14 Bus System using Mi Power Software

First of all, a state of the art regarding the methods to solve optimal power flow (OPF) and its application in electrical microgrids are presented in this article. Afterward, a mathematical algorithm based on the gradient method is proposed to implement OPF to a low-power electrical microgrid, with the objective of improving the voltage's characteristics and reducing the active power losses. Finally, the proposed algorithm is applied to low-power electrical microgrid with photovoltaic generation to demonstrate the effectiveness of the method.

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Optimal power flow in electrical microgrids

The load-flow study is a numerical analysis of the flow of electric power in an interconnected system in power engineering. Simplified notation such as the one-line diagram and per-unit system is used for power-flow study and focuses on various features of AC power parameters, such as voltages, voltage angles, real power and reactive power. It analyses the power systems in normal steady-state operation. So, the load flow studies play a major role in analyzing of the power systems. Generally, power system buses are categorized into three classes named load bus, power grid bus and slack bus or swing bus. In fact, slack buses in the power system are chosen among PV buses and also voltage value and phase angle of slack buses must be set 1 and 0, respectively. In this study, analysis of power flow was performed on six bus bar system using Gauss Seidel method. The study analyzed the change of effects that come from choosing different slack buses to determine the critical stress points, voltage stability, in the multi-bus systems. At the beginning of the each power flow analysis, different busses which have generator were determined as the slack bus and the analysis was performed without increasing the load. The effects of changes in critical points were examined at the end of the all possible analysis.

Investigating the effects of selecting different slack bus on power systems

This paper presents an approach to obtain the optimal load flow solution using three different intelligent techniques such as particle swarm optimization (PSO), crazy particle swarm optimization (CPSO) and hybrid differential evolution (HDE) subject to various system constraints. The above optimization techniques have a capability to provide global optimal solution in problem domains where a complete traversion of the whole search space is completely infeasible. The proposed method has been tested on Ward and Hale six bus system and IEEE-14 bus test system. The solutions obtained are quite encouraging and useful in solving the optimal load flow problem. The algorithm and simulation are carried using Matlab software.

P.G. Rizwankhan

Papers

Implementation of non-traditional optimization techniques (PSO, CPSO, HDE) for the optimal load flow solution