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.

Robust mapping rule estimation for power flow analysis in distribution grids

Abstract: The increasing integration of distributed energy resources (DERs) calls for new monitoring and operational planning tools to ensure stability and sustainability in distribution grids. One idea is to use existing monitoring tools in transmission grids and some primary distribution grids. However, they usually depend on the knowledge of the system model, e.g., the topology and line parameters, which may be unavailable in primary and secondary distribution grids. Furthermore, a utility usually has limited modeling ability of active controllers as they may belong to a third party like residential customers. To solve the modeling problem in traditional power flow analysis, we propose a support vector regression (SVR) approach to reveal the mapping rules between different variables and recover useful variables based on historical data. We illustrate the advantages of using the SVR model over traditional regression method that finds line parameters in distribution grids. Specifically, the SVR model is robust enough to recover the mapping rules when the regression method fails. This happens when 1) there are measurement outliers, 2) there are active controllers, or 3) measurements are only available at some part of a distribution grid. We demonstrate the superior performance of our method through extensive numerical validation on different scales of distribution grids and IEEE test buses. Robustness of our method is observed.

Optimal Allocati on of Distributed Generation in Distribution System for Loss Reduction

Abstract: I ntegration of renewable energy based distributed generation (DG) units provides potential benefits to conventional distribution systems. The power injections from renewable DG units located close to the load centers provide an opportunity for system voltage support, reduction in energy losses and emissions, and reliability improvement. Therefore, the allocation of DG units should be carefully determined with the consideration of different planning incentives. This paper presents a simple method for real power loss reduction, voltage profile improvement, substation capacity release and is based on voltage sensitivity index analysis. Power flow analysis is done using the forward-backward sweep method. Study carried out on an IEEE-33 bus test system validates the suitability of this proposed method. Keyw ords: rad ial distribution system, distributed generation, renewable energy sources, voltage sensitivity index, real power loss.

Development of unbalanced three-phase distribution power flow analysis using sequence and phase components

Abstract: This paper presents a new power-flow method for analyzing unbalanced distribution networks. In this method, an unbalanced distribution network Is decomposed to: 1) main three-phase network with three-phase line segments and 2) unbalanced laterals with two-phase and single-phase line segments. The proposed method allows solving the main three-phase network based on the decoupled positive-, negative, and zero-sequence networks. The unbalanced laterals are solved using the forward/backward method In phase components. The solution process Involves three main steps. Firstly, In phase components, the backward step Is executed to calculate an equivalent current Injection for each unbalanced lateral. Secondly, the main three-phase network Is solved In sequence components. The standard Newton-Raphson and fast decoupled methods are used for solving the positive-sequence network whereas the negative- and zero-sequence networks are represented by two nodal voltage equations. Finally, In phase components, the forward step Is performed to update the voltages In the unbalanced laterals. The three-steps are repeated till convergence happen. Distribution network characteristics such as line coupling, transformer phase shifts, voltage regulators, PV nodes, capacitor banks, and spot or distributed loads with any type and connection are considered. Solution of unbalanced radial feeders shows that the proposed hybrid algorithm Is accurate.

Multi-stage Dynamic Optimal Power Flow in Wind Power Integrated System

Abstract: Wind power generation is increasingly causing great attention of people. And its development will bring new challenges to traditional power systems. This paper researches the problems of optimal power flow (OPF) including wind farms. A multi-stage dynamic optimal power flow model is presented. The power flow calculation considering wind farms is necessary in this model. The paper analyzes the shortages of present flow calculation method for wind power integrated system. The Q-V formulation of the induction generator is deduced. Based on it, a new flow computation method is presented. And the method is used in the multi-stage dynamic optimal power flow model. An example of IEEE power systems gives an illustration of the feasibility of the presented method

Modified Newton-Raphson load flow analysis for integrated AC/DC power systems

Abstract: The significant increase in planned offshore wind parks and the tendency towards large parks in considerable distances offshore, make the well established HVDC technology a favorable solution for the connection of these large & distant offshore wind parks to the main power grid onshore. It is therefore necessary to adequately model the HVDC transmission links and integrate them in the load flow analysis of the complete AC-DC system. In this paper, the well known Newton-Raphson method for the load flow analysis is modified to achieve compatibility for AC-DC systems with integrated DC links in the AC network. The elements of the residual vector and the Jacobian matrix for the AC network are kept unchanged and are merely complemented by a new vector and a new matrix, which represent the modifications due to the DC link. The modified Jacobian equation includes the DC real and reactive power at the AC-DC buses, and their dependency on the AC system variables. The modified Newton-Raphson method is evaluated on an AC-DC test system with a load flow computation in Matlab and the results are presented.