| When the system is under static condition, the existing commercial synchronous phasor measurement algorithm can achieve good effect, but under dynamic condition, the system frequency and the amplitude change over time, which causes that the precision of algorithms fell sharply, and it subsequently fails to meet the requirements of practical application of phasor measurement. At the same time, how to use time domain and frequency domain information of signal will directly affect the indicators of synchronized phasor measurement algorithm, such as ductility, computational complexity, and further affect the performance of the wide-area measurement system advanced application. Therefore, this thesis focuses on the dynamic synchronous phasor measurement algorithm, and studies its application in forced oscillation disturbance source location. The main work of this paper is as follows:(1) Dynamic synchronous phasor measurement algorithms based on frequency domain information of signal are studied, including dynamic phasor estimator based on frequency-domain model DPEFM and phasor estimator based on frequency-domain information considering decaying DC components PFIDC. DPEFM is based on dynamic signal Taylor series model, and several phasor estimations of the bins around the fundamental bin in frequency domain are obtained by filters using the same data window to solve the model parameters, which greatly improves the precision of phasor measurement. On the basis of DPEFM, PFIDC algorithm is proposed considering the influence of decaying DC component. PFIDC is based on dynamic signal Taylor series model containing decaying dc component, and makes full use of frequency domain information to estimate the model parameters of time-variation and decaying DC component. PFIDC reduces the influence of decaying dc component and has the advantages of fast dynamic response, short time delay, can meet the IEEE standard for measuring requirements of the protection class PMU.(2) The dynamic phasor estimation algorithm based on the frequency-domain information obtains short delay but heavy computational burden, while that based on the time-domain information obtains light computational burden with long delay. The algorithm for dynamic phasor estimation based on the time-frequency information was proposed to balance the tradeoff of time delay and computational burden. Firstly, the Discrete Fourier Transform (DFT) based phasor estimations from different data windows and at different frequency bins were calculated with Taylor-series phasor model. Then, the time-frequency information of the DFT based phasor estimations were analyzed in detail, and modified phasor estimation was provided. Finally, phasor estimation at the report time was obtained by phase shift operation. Test results of both ideal signals and PSCAD/EMTDC generated signals shows that the proposed algorithm can provide accurate phasor estimations under conditions of power oscillations and frequency deviations. The time delay and the computational burden can be optimized by selecting the number of data window and frequency bin to meet the requirement of practical application.(3) At the beginning of forced oscillation, the frequency of the disturbance source unit is always fluctuating ahead of that of other units. Thus it’s effective to determine the bus unit which is close to the oscillation source by estimating the phase relationship of forced oscillation frequency signal of synchronized phasor measurement units, which is the key to disturbance source location with the application of frequency characteristic. This paper introduces the dynamic phasor measurement algorithm to measure the frequency increment of units bus, and analyzes the oscillation waveform of the bus frequency increment in the perspective of phase, and finally locates the disturbance source. Theory and simulation analysis shows that, the phase analysis of dynamic frequency phasor can determine the unit bus which is first to arrive the first extremum of oscillation simply and effectively, and further obtain the time lag of bus arrived at the first extremum of oscillation, which provided a new way for the practical application of frequency characteristics on the disturbance source location. |
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