SVD Applied to Voltage Sag State Estimation

Abstract

Abstract-The method presented in this paper addresses the problem of voltage sag state estimation (VSSE). The problem consists in estimating the voltage sags frequency at non-monitored buses from the number of sags measured at monitored sites. Usually, due to limitations on the number of available voltage sag monitors, this is an underdetermined problem. In this approach, the mathematical formulation presented is based on the fault positions concept and is solved by means of the Singular Value Decomposition (SVD) technique. The proposed estimation method has been validated by using the IEEE 118 test system and the results obtained have been very satisfactory.Index Terms-voltage sags (dips), power quality monitoring, power system, Power Quality. I. INTRODUCTIONOLTAGE sags (also known as voltage dips) are a frequent power quality disturbance that can cause failure or malfunctioning to very common devices used in industrial and tertiary sectors. This disturbance, as with other power quality problems, must be approached from a compatibility point of view that requires characterizing the equipment sensitivity as well as the power system behavior. This paper relies on this second aspect.In order to describe the voltage sags performance in the power system, a method must be established that can provide representative values of the expected number and characteristics of voltage sags at system buses. To quantify the system behavior, a great emphasis has been placed recently on the use of different quality indices. Some of these indices are defined at a site level (for a specific point of the supply system), but there are others defined at a system level (for the whole system) [1]- [4]. For assessing site indices, monitoring the power supply at the site of interest can directly provide the information to evaluate the index. However, in order to calculate voltage sag indices of the whole system, ideally the monitoring of all sites should be required. Clearly, such a monitoring program is not economically justifiable.This work has been financed by the Ministerio de Ciencia e Innovación (MICINN), Spain, under project ENE2010-17459 (CON) A. Hernández, R. M. de Castro and M. Izzeddine are with the

Voltage sag state estimation based on -normminimization methods in radial electric power distribution systems

“…Several mathematical and stochastic approaches have been formulated to solve the voltage sag estimation problem [9], [11], [15]. Stochastic methods are subject to high inaccuracies due to the network fault uncertainties and it is not possible to assess the optimality and convergence criteria in the results obtained.…”

“…In [11], the mathematical formulation in (1) is development to voltage sag estimation. This formulation is explained below.…”

“…The results of these methods are sensitive to the high variability of fault statistical data, so the voltage sag number may be inaccurate. VSE problem can also be formulated as an undetermined linear system based on the fault position concept [11]. Singular Value Decomposition (SVD) technique allows to estimate the number of voltage sags in unmetered busbars.…”

Time-domain harmonic state estimation of nonlinear load power systems with under-determined condition based on the extended Kalman filter

“…The SVD obtains a unique estimated solution if the system is over or normal-determined, m > n or m = n, respectively. When the system is under-determined, m < n, which is the examined case in this paper, the SVD obtains an estimated solution with minimum norm and defines the system observability [33][34][35]. The nonlinear measurement model must be linearized using the Taylor's formula about an initial condition of the states x 0 , i.e.…”

Sistema de monitoramento para estimação de estado harmônico trifásico para sistemas de distribuição utilizando decomposição em valores singulares

“…Vale frisar também que esta junção de conceitos trata de uma lacuna ainda aberta nos métodos até o momento encontrados na literatura, pois a maioria dos trabalhos apresenta os dois métodos de maneira separada. Além disso, como será detalhado no capítulo seguinte, grande parte dos trabalhos encontrados refere-se a algoritmos de estimação voltados para sistemas de transmissão da energia elétrica (MELIOPOULOS;ZHANG;ZELINGHER, 1994;DU;WATSON, 1996;DU et al, 1999;KANAO et al, 2005;CASTILLO, 2006;HERNÁNDEZ et al, 2013;CISNEROS-MAGAÑA;MEDINA, 2013). Já grande parte dos métodos de alocação de medidores de QEE considera apenas sistemas balanceados (MARÍN et al, 2003;ELDERY et al, 2006;REIS et al, 2008;KETABI;NOSRATABADI; SHEIBANI, 2012) e/ou são voltados para a medição de afundamentos de tensão (ALMEIDA; KAGAN, 2011b;KAZEMI et al, 2013;WONG, et al, 2014;SANTOS, 2014;GOMES et al, 2016).…”