Tolerances Of Phasor Measurement Unit. How To Take Into Account And Decrease Them

Abstract

Phasor measurements – is one of the most important technologies for measuring the electric power regime parameters, which is part of the Wide Area Monitoring, Protection and Control System complex. Formally, phasor measurements replace the existing systems of telemetry and distance measurements SCADA due to higher sampling rate, time synchronization and high-performance. Phasor measurement unit (PMU) having been used since early 2000s all around the world, and the potential of their application has not yet been fully disclosed. The issues of assessing the tolerances of PMU are considered in foreign literature. There is a standard [1] in Russia, which regulates the tolerances of PMU. According to the standard, class M PMU (for measurements) and class P PMU (for protection) have different permissible limits of tolerances. The standard also specifies the ranges of permissible tolerances for different operating conditions of PMU – static and dynamic. Moreover, there is a way of changing the input parameters of PMU for which the limits of permissible tolerances are specified for each of the conditions. The method of calculating the main types of tolerances (total vector error TVE, frequency measurement error FE and rate of frequency change error RFE) is also determined in standard. It is necessary to consider the reasons for the appearance of those tolerances in the conditions of changing the electric regime parameters in order to understand what determines the measurement tolerance of PMU on a real power grid.