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Maiara C. Oliveira
Departamento de Engenharia Elétrica, Universidade de São Paulo, SP
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Murilo E. C. Bento
Departamento de Engenharia Elétrica, Universidade Federal do Rio de Janeiro, RJ
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Joao B. A. London Jr
Departamento de Engenharia Elétrica, Universidade de São Paulo, SP
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Rodrigo A. Ramos
Departamento de Engenharia Elétrica, Universidade de São Paulo, SP
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Ahda P. Grilo-Pavani
Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas, Universidade Federal do ABC, SP
Keywords:
Observability, Critical Measurement, PMU, WAMS, State Estimation, Voltage Stability
Abstract
State estimators (SEs) are among the most important tools for power system real- time modeling. With the advent of Wide-Area Measurement Systems (WAMSs), combinations of measurements from Phasor Measurement Units (PMUs) and Remote Terminal Units enabled the development of highly accurate SEs. However, although the PMUs provide much more information about the system state, typical issues faced by real-time state estimation applications still remain, such as the ones related to observability of the measurement sets. Within this context, this paper proposes (as its main contribution) a modified state estimation process to monitor the voltage stability margin of buses that are not directly monitored by meters. To achieve this goal, a well-known method based on the H∆ matrix was extended to perform redundancy and observability analysis of metering systems containing only PMU measurements, using rectangular coordinates for the phasor measurements and state variables. A linear Weighted Least Squares SE is implemented to estimate the complex voltage of observable buses, regardless of the presence of PMUs in them. Based on all estimated state variables, the voltage stability margin of the whole system is also estimated. Simulation results carried out in the IEEE test systems of 14, and 118 buses validate the effectiveness of the proposed scheme.
