Multiple Frequency Taylor Model-Based Dynamic Synchrophasor Estimation Algorithms

In order to further enhance the measurement performance under dynamic conditions,so that the measurement accuracy under dynamic conditions and the response speed under transient conditions can meet the requirements of the dynamic phasor measurement for monitoring the power system,a new multiple frequency Taylor model(MFTM)is proposed in this paper for dynamic phasor estimation,which aims to extend the single Taylor dynamic model for M-class application to suppress the adverse effect of dynamic characteristics.Moreover,two kinds of algorithms based on MFTM are proposed to trade-off both the estimation precision as well as response time by considering the time domain or frequency domain information.Finally,according to the proposed algorithms,in order to have an intuitive understanding of the actual measurement performance of the online PMUs,an online assessment method of PMUs dynamic performance and its evaluation index are proposed in this paper for the goal that exploring a new way for the online evaluation of PMU dynamic performance and break through the limitation that the traditional index cannot be calculated under the online operating conditions of PMUs.Firstly,according to the latest IEEE standard in synchronous phasor measurement for Pclass PMUs,the multiple frequency Taylor model(MFTM)is employed to dynamic phasor model to describe the dynamic characteristics of the supplied signal,which can be decomposed into several sub-phasors with rotating frequency around the fundamental frequency.Secondly,STFT is employed to attain the initial fundamental phasor estimation at different reference time with various data windows or various filter frequency of the DFT.Third,several signal parameter estimation methods such as linear least squares are employed to estimate the accurate estimations of dynamic phasor and dynamic frequency.Moreover,the pre-estimated frequencies of MFTM are all derived from the historical data outputs by the PMUs,which are used to consider the influence of frequency deviation.Finally,a phase shift operation is adopted to shift the phasor estimations to the report time.Simulations results and field data test demonstrate that proposed algorithm can improve the measurement accuracy efficiently with an acceptable increment of computational burden under various dynamic conditions.A new online assessment method based on fluctuation characteristic of phasor variation is proposed to evaluate the measurement performance of PMUs.Firstly,the relationship between fluctuation characteristic of phasor variation and performance of phasor measurement algorithm is analyzed in detail.Then,the standard deviation which used to quantify the volatility amplitude of phasors' variation is defined as the volatility index to stand for measurement accuracy.Thirdly,the volatility index is obtained real-timely via adjacent phasor measurements.Finally,various phasor measurement algorithms are employed to evaluate the performance of proposed method under dynamic conditions such as frequency ramping,power oscillation and noise disturbance.The results show that the volatility index is coincident with the Total Vector Error(TVE)under most of the circumstance.Validity and practicability of the fluctuation index as the online evaluation index of dynamic phasor measurement performance are fully verified.This paper is proposed to expand the comprehensive performance of dynamic phasor measurement algorithm as well as explore online assessment for measurements performance of PMU.According to the theoretical derivation and simulation results,the MFTM and the volatility index provide new ideas for a dynamic synchrophasor phasor measurement algorithm and its relevant studies.Under the background the operation ability of DSP has greatly improved,it is meaningful for PMUs to get a comprehensive performance improvement at the cost of an acceptable increment of computational burden.