Power-flow study

About: Power-flow study is a research topic. Over the lifetime, 8091 publications have been published within this topic receiving 155053 citations. The topic is also known as: load-flow study.

Active-reactive optimal power flow for low-voltage networks with photovoltaic distributed generation

Abstract: Photovoltaic systems (PVSs) are more and more installed in low voltage distribution networks (LV-DNs) for absorbing solar energy. Features of such networks need to be analyzed for a reliable and optimal design as well as operation. In this study, we introduce a mathematical model derived from a combined active-reactive optimal power flow (A-R-OPF) for LV-DNs by taking into account the reactive power capability of photovoltaic distributed generation (DG). Using multiple performance criteria, it is possible to analyze the impact of controlling reactive power sources LV-DNs. A real 29-bus LV-DN is employed to demonstrate the effectiveness of the proposed method, based on which interesting results have been achieved. For instance, up to 25% of annual energy costs can be saved and there is no need in this case study to use battery storage systems (BSSs) in LV-DNs for accommodating spilled PV energy.

Information-Energy Flow Computation and Cyber-Physical Sensitivity Analysis for Power Systems

Abstract: Power systems are the typical cyber-physical systems in which the closed-loop hierarchical control systems (HCSs) are widely used to ensure their stable and safe operation To describe the coupling operation mechanism of an HCS and power grid by expanding current steady-state power flow analysis theory, we propose an information-energy flow model and develop a matrix-based computational approach With the help of the methods, we can directly calculate the mutual influence of the cyber and physical parts Since the mechanism of power flow computation is mature, we focus on the cyber side, proposing an information-flow-oriented network model as well as a matrix-based computation method for its information flow In particular, we develop a minimum-cut-set-based partition and equivalence method to address a complex cyber network with non-linearity issues associated with data processing Subsequently, we discuss cyber-physical sensitivity and vulnerability issues In the case study, we calculate the information-energy flow of an IEEE 14-node system with real time-voltage stability monitoring and control application and compare the results with simulation results The similarity of the results between the two methods verifies the effectiveness of our approach

Performance Evaluation of Parameter Estimation Algorithms for Economic Operation of Power Systems

Abstract: Four algorithms for estimation of the parameters of models used in optimal economic operation of electric power systems, are proposed. The details of the formulations for estimating the parameters of the fuel cost expression, the loss formula coefficients, and the active-reactive power loss models are highlighted. Critical performance evaluation of each of the proposed algorithms is carried out using some practical test systems. The first evaluation criterion is based on the familiar modeling error-comparison. Further evaluation is carried out on the basis of the optimal strategies resulting from the use of each estimated model. Optimal costs as well as overall network performance (based on load flow analysis) resulting from the implementation of each model, provide the basis for our comparisons.

Decomposition approach for minimising real power losses in power systems

Abstract: An efficient method for minimising real power losses and improving the voltage profile of large scale power systems is presented. The problem is solved through optimal adjustments of reactive power generation in the system by changing generator voltages, shunt capacitors, and tap setting of tap changing transformers. It is formulated in a linearised form suitable for the linear programming technique and decomposition methods. The power system planning and corresponding problems with the addition of new reactive power sources have been integrated with the operational characteristic of the system, and results have been presented. The proposed method does not require the inversion of the Jacobian matrix, and its superiority lies in the reduction of the computation time and memory space, as well as a fast convergence for the solution of large scale systems.

Dynamic computing paradigm for comprehensive power flow analysis

Abstract: In this study, a novel dynamic paradigm aimed at solving the power flow equations in both solvable and unsolvable region is proposed. The challenging idea is to reformulate the power flow equations into a set of ordinary differential equations, whose equilibrium points represent the power flow problem solutions. Starting from the Lyapunov theory, the authors demonstrate that this system of dynamic equations is characterised by an exponential asymptotic convergence to equilibrium points. This feature allows us to overcome the inherent limitations of the traditional iterative minimisation algorithms that can fail to converge because of the highly non-linearities of the first-order condition. Extensive simulation studies aimed at demonstrating the effectiveness of the proposed methodology are presented and discussed.