The Research On Electric Energy Measurement And Calibration Method Under Dynamic Load Environment

In modern power system,the conncetion of the stochastic volatility,nonlinear,and impact load such as the electrified railways,frequency con version devices,electric vehicle charging piles,and high-power drag devices,makes the deterioration of the current power quality.It not only creats serious influence on the normal and stable work of the electrified equipments,but also generates seriou s distortion of the signal waveform in power network.These phenomena bring great challenges to the accuracy and rationality of the electric energy metering equipments.T he accurate measurement of energy under dynamic load environment can provide a proof o f the economic settlement among power station,power transmission,transformation department and users in the energy market.The way of measuring energy quickly and accurately,determines the direct economic benefits of the three parties.It is an urgent demand for both power supply and demand in a dynamic load environment.Firstly,the research background and significance of energy measurement technology are described,the basic concepts and classification indicators of steady-state and unsteady-state signals are introduced and the existing energy measurement techniques under steady-state and unsteady-state conditions are analyzed in this thesiss.The status,the principle,advantages and disadvantages of electric energy measurement equipment under the existing dynamic load is given.Aiming at the problem of electric energy measurement under dynamic load environment,the influence law of distorted signal under dynamic load environment are analyzed.The simplified model of grid signal under steady-state and unsteady-state conditions is constructed respectively,and the mathematical model of power measurement under dynamic load is derived.The adaptability of IEEE Std1459-2010 energy measurement standard is studied,and the existing energy measurement methods are deeply researched and compared.In order to realize the accurate measurement of electric energy under dynamic load environment,a method of frequency-shifting filtering is adopted to measure the frequency in this thesis.By analyzing the reason of the time deviation of asynchronous sampling of signals,the formula for calculating the time deviation caused by asynchronous sampling is derived.A method for calibration the time deviation under asynchronous sampling is proposed.The modified 2nd-order compound Newton-Cotes integral algorithm is derived.According to this,a modified compound Newton-Cotes energy measurement under dynamic load environment is established.Finally,the test signal under steady and unsteady state are used to simulate and verify the proposed algorithm.The results show that the method proposed can realize the energy measurement under dynamic load environment accurately and effectively.Aiming at the calibration problem of energy measurement under dynamic load,the law of error is deeply analyzed.The DC offset of the voltage and current signal channel are derived.For the compensation and ratio difference calibration method,angle calibration method by using linear interpolation is proposed and the correction formula is given in this thesis.The influence law of electric energy measurement at different temperatures is analyzed.The cubic angle interpolation method is proposed to compensate the difference angle error compensation algorithm for energy measurement under dynamic load.In order to verify the real-time and effectiveness of the energy measurement and calibration method in the dynamic load environment proposed in this thesis,A new electric energy measurement devices under the dynamic load environment based on the ADC+DSP+ARM architecture is established.In the measurement test device platform,the ADS1278 is used as the data acquisition unit,the TMS320C6745 is used as the data processing unit,and the MK66FN2MOVLQ18 is used as the hardware circuit design of the management unit.The design flow of the system software modules are given.The energy measurement test platform under dynamic load environment,is constructed the actual measurement,and the effectiveness and accuracy of the electric energy measurement and calibration methods proposed is verified by the experimental tests.