Electric Power Network State Tracking From Multirate Measurements

Abstract

This paper proposes a novel tracking state estimator to process both fast-rate synchronized phasor and slowrate SCADA measurements. The former are assumed to be in limited number. The latter are exploited as and when they arrive to the control center. In order to restore observability, after each execution of the tracking state estimator, forecasted SCADA measurements are used as pseudo-measurements in the next estimation. An event detection analysis allows assessing if the system is in quasi steady-state. If so, an innovation analysis is performed to identify and eliminate erroneous SCADA measurements. The system state is computed by Hachtel's augmented matrix method. The option of exploiting time-tagged SCADA measurements is also considered. The method is illustrated through detailed dynamic simulations of a test system evolving towards voltage collapse, with and without emergency control.

Unscented Rauch–Tung–Streibel smoother‐based power system forecasting‐aided state estimator using hybrid measurements

“…Utilisation of unsynchronised measurements to estimate the system states results in inaccurate estimates. This issue is widely known as the time skew problem [19] and is further discussed in the next section.…”

“…Reference [19] proposed a method to overcome the timeskewness issue by processing the SCADA and PMU measurements as and when they arrive. To ensure observability, predictions obtained using the KF are used as pseudo-measurements.…”

“…Future measurements contain relevant information about the slow changing dynamics of the power system, which can be utilised to reduce the errors injected by the prediction models used in the algorithm. RTS smoother-based FASE reduces the estimation error inherent in the forward prediction-based time-skewness handling technique discussed in [19]. • An unscented transform-based RTS smoother is utilised to handle the higher order non-linearities which cannot be handled effectively using the derivative-based linearisation approach, discussed in [21].…”

“…• An unscented transform-based RTS smoother is utilised to handle the higher order non-linearities which cannot be handled effectively using the derivative-based linearisation approach, discussed in [21]. A detailed comparison between the proposed approach and works discussed in [18,19,21] are tabulated in the simulation results section. • The effectiveness of the proposed estimator in handling anomalous situations like communication link failure is studied in this paper.…”

Enhanced Modelling Framework for Equivalent Circuit-Based Power System State Estimation

“…All techniques proposed in [5]- [12] employ WLS-based estimators and are therefore solved iteratively due to their inherent nonlinearity. Apart from WLSbased methods, some of the most recent alternative approaches include HSE based on the Least Absolute Value method [13] and decentralized HSE [14]. In all of these cases the inherent nonlinearity of the measurement functions causes a significant computational burden.…”