High-Precision Estimation Of Wideband Synchrophasor Of Electrical Signals With Heavy Noise

To cope with the fossil energy crisis and the environment pollution,it has become the universal consensus and concerted action of all countries around the world to vigorously develope renewable energy and accelerate the electrification of loads.As the proportion of power electronics device-based wind power and photovoltaic renewable energy generation,AC/DC transmission and distribution grids,and electric vehicle is increasing,the power system presents a high degree of power electronics.The power-electronied power system has the characteristics of low inertia and weak damping,which will weaken the system resilience and the ability of suppressing low-frequency oscillations,threatening the system frequency stability and the stability of regional grid interconnection operation.In addition,wide frequency band.The large-scale application of power electronic devices injects a large number of low-frequency and high-frequency components into the power grid,which makes the signal present wideband.The interactions between the inverter and system,and between the inverter and inverter,will cause wideband power oscillation.The oscillation frequency varies from a few Hz to several kHz,which may cause the unit trip,damage the device,and even excite the system resonance.Wideband frequency signal due to nonlinear load can cause power quality problems,system resonance,and relay protection malfunctions.Therefore,the system dynamics become more complex and is difficult to predict.The traditional model-based off-line analysis and control methods can hardly cope with the complex dynamics of power-electronized power system.Although WAMS can track the power system dynamic,it only measure the fundamental frequency component and cannot deal with a series of problems due to wideband components.To improve the operation monitoring capability of the highly power-electronized power system,it is necessary to expand the synchronous measurement range from the narrowband fundamental frequency component to the wideband frequency components.It is imminent to develop a new-generation wideband measurement-based panoramic monitoring technique that covers all the levels of generation,transmission,distribution,and load.However,the signal of power-electronized power system not only wideband frequency components,but also contains noise.In particular,the signal of distribution systems is seriously affected by heavy polymorphic noise,including background noise and stochastic impulsive noise.The existing estimation method of wideband synchrophasor lacks the ability of adaptivly sensing wideband components and the robustness for the interference of heavy polymorphic noise.Therefore,it is difficult to achieve high-precision estimation of wideband synchrophasor.In fact,there has been no special research on the high-precision estimation methods of wideband synchrophasor under heavy polymorphic noise condition at home and abroad.Therefore,this paper focuses on the problems of the adaptive sensing of wideband components,the high-precision identification of wideband signal and noise,and the high-precision estimation of wideband synchrophasor under heavy polymorphic noise condition.The research mainly includes:(1)An improved model of wideband signal considering polymorphic noise is established,which is the research foundation for the adaptive sensing of wideband components,the identification of high-precision wideband signal and noise,and the high-precision estimation of wideband synchrophasor under heavy polymorphic noise condition.The adaptive tracking threshold of noise level in frequency domain and its iterative estimation algorithm are proposed.Based on this threshold,the adaptive sensing algorithm of deterministic component is proposed.The effectiveness of the proposed adaptive sensing algorithm is verified using both simulation tests and field data.(2)A high-precision identification method of wideband signal and noise is proposed,which realizes the adaptive filtering of stochastic impulsive noise,the effective sensing and high-precision identification of deterministic components,and the adaptive decomposition and high-precision identification of polymorphic noise.Simulation results verify effectiveness and precision of the proposed algorithm.Finally,the wideband frequency distribution characteristics of deterministic components and the probability distribution characteristics of polymorphic noise are analyzed using the proposed high-precision identification method based on the field current data.The analysis results of field data provide an important reference for the study of high-precision estimation method of wideband synchrophasor.(3)A method based on fixed filter-matrix robust local regression smoothing(FWRLRS)iterative filtering and fast Taylor Fourier transform(FTFT)for the high-precision estimation of wideband synchrophasor is proposed,which relies on the fast suppression for stochastic impulsive noise in time domain and least squares suppression for background noise in the estimation process.The simulation results show that the proposed method can achieve high-precision estimation of wideband synchrophasor and frequency under heavy polymorphic noise condition.Finally,the maximum tolerable ability of the proposed method for the polymorphic noise is analyzed,providing the selection criteria for algorithm parameter in practical applications.(4)The high-precision measurement prototype of wideband synchrophasor is developed.The test results show that the developed prototype can achieve high-precision estimation of wideband synchrophasor and frequency under heavy polymorphic noise condition.Finally,the developed prototype is installed and runs at an electric vehicle charging station,and the wideband synchrophasor and frequency measurement information is collected and analyzed.