Analysis Of Capacitor Voltage Transformer Measurement Error And Its Influence On Statistical Line Loss Of Ultra-high Voltage Transmission Line

With the development of power system,the accuracy of col electrical energy measuring of UHV cross region transmission is increasingly significant.Capacitor voltage transformer(CVT)is the major voltage-measuring facility of UHV,which is the basis of power measurement and energy metering.Statistical line loss that indicats transmission efficiency is hard to measure due to its negligible size.This paper examines UHV line CVT measurment error and its effect on statistical line loss via theoretical analysis,numerical simulation and dynamic simulation experiment.First of all,CVT measurement accuracy is considered.Several error components were dicussed.Capacitive divider and electromagnetic unit were studied as intrinsic error.Three fators,proximity effect,temperature and frequency,were dicussed as additional error.Among them is the temperature,which is detailedly analysed and described as a mathematical model describing temperature inhomogeneity of capacitive divider.A method of synthesizing error components is given in the basis of error theory.Next,the effect of CVT measurment error on statistical line loss is studied.The range of CVT error was calculated.The relation between statistical line loss and CVTs error at both ends of line is deduced.It shows that when considering CVTs error at both ends,statistical line loss is a function of transmitted power in the basis of PI equivalent circuit.A UHV line simulation model with CVTs was bult in PSCAD in order to validate the theory analysis.It is found that under certain circumstances statistical line loss becomes minus.The determinant conditions of minus statistical line loss was given and validated.After that,A CVT dynamic simulation model was desined and developed.Five design rules are proposed.The model's structure was desined.The parameter and component precision were calculated.Load characteristics experiments of the six prototypes were conducted,which shows good ability in load capacity.At last,a sereis of experiments were conducted on the 1000 kV dynamic simulation line.Preliminary experiment,dynamic simulation line statistical line loss measurement,considering capacitor change of CVTs statistical line loss measurement and metering were conducted one by one.The experiments reproduce the result of theoretical analysis and validate the theroy qualitatively.