An Adaptive Synchrophasor Measurement Method Considering Injected Out-of-band Interference

In order to optimize the synchrophasor measurement performance under the out-of-band interference and meet the measurement error requirements of the fundamental phasor and frequency which are specified in the latest IEEE standard,a hybrid phasor model containing both the fundamental phasor and the out-of-band phasor is established.Moreover,the fundamental and the out-of-band phasors in this model are divided into some pairs of sub-phasors,which aims to enhance the ability of the phasor model to represent the dynamic characteristics,so that the proposed algorithm can face some complex conditions including dynamic changes as well as static interferences.In addition,a real-time monitoring scheme of the out-of-band interference is designed in this paper to optimize the calculation and response time of the measurement algorithm.Based on this,an adaptive synchrophasor measurement algorithm considering out-of-band interference is proposed.Firstly,a phasor model of the out-of-band interference is built based on Taylor series considering the existence of the out-of-band interference in power signals.Together with the fundamental phasor,a hybrid phasor model is given.Considering the dynamic characteristics of power signals,the hybrid phasor model is improved by using some paired sub-phasors to synthesize the fundamental and the out-of-band phasor,which can juggle the dynamic conditions and the out-of-band interference.To solve the above phasor models,firstly,the DFT filtering and spectrum analysis are carried out for the sampling sequence in a specific frequency range,and then the fundamental and out-of-band frequencies are pre-estimated through the frequency values corresponding to the peaks of the spectrum in different frequency ranges.Secondly,the off-line coefficient matrices are invoked so that the fundamental and out-of-band Taylor derivatives can be obtained by the least square method.Finally,combining the multiple derivatives of fundamental AM/FM model as well as the fundamental phase information at the front and back half cycle of the reference time,the fundamental phasor and frequency at the reporting time of PMUs can be output through a phase-shift operation.The simulation results based on MATALB show that the proposed synchrophasor measurement algorithm can not only meet the measurement error requirements of TVE≤1.3%,FE≤0.01 Hz under the ideal out-of-band interference,which are specified in IEEE standard,but also own higher measurement accuracy when some dynamic conditions and out-of-band interference exist at the same time.Furthermore,it is able to resist noise and harmonic interference to a certain extent.According to the actual situation of out-of-band interference in power grid,firstly,the simplified signal model and its solution method are given when the out-of-band interference does not exist.Secondly,the fundamental and the out-of-band frequency ranges are divided into some subintervals,so that the identification scheme of the out-of-band interference is designed through the DFT filtering at the center frequency of these subintervals as well as the frequency scanning results by DFT in the corresponding subintervals.The simulation results show that the proposed algorithm can fully meet the measurement error requirements of IEEE standard under various static and dynamic conditions.Moreover,the suitable models and calculation methods can be invoked in real-time according to the monitoring results of out-of-band interference,thereby realizing the adaptive measurement of synchrophasor and juggling the accuracy,response speed and calculation of the algorithm.In this paper,some work is carried out on the adaptive synchrophasor measurement algorithm considering out-of-band interference.The theoretical deduction and simulation results show that the proposed hybrid phasor model and its improved form can not only provide a theoretical basis for the accurate extraction of fundamental phasor under complex interference,but also give new ideas for the new generation of PMU to realize the adaptive synchrophasor measurement under various dynamic or static conditions.