| Electric energy is an important form of energy in modern society,and the electric power industry has become the basic industry of the whole society.The safe and reliable operation of power system is very important,but the harmonic pollution of power system is an important factor affecting the stable operation.And with the vigorous development of new energy sources,such as solar energy and wind energy,how to realize the efficient,safe and rational utilization of new energy under the large-scale development will be the core content and important goal of the future smart grid construction.Intelligent power meter as the key node between the user and the smart grid,it will be the objective needs of the future development of smart grid due to realize the monitoring of the power grid operation state and power quality.At the same time,it is also the key equipment for smart grid to achieve the rational allocation and utilization of new energy.The paper studies and designs a high-precision intelligent power meter,which is used to monitor the operation state and power quality of the power grid under this context.First,paper analyzes the calculation principle of each basic electrical parameter and its digital realization according to the detection principle of intelligent power meter.In view of the power quality analysis function,the FFT harmonic analysis method under discrete sampling of AC signals is discussed,and the basic principle of Fourier transform is introduced.Because of the use of FFT harmonic analysis leads to spectral leakage fence effect and other issues,Therefore,paper discusses the characteristics of various window functions and their application in FFT algorithm,and proposes the FFT harmonic analysis method based on Nuttall window interpolation algorithm and the implementation methods of each power quality parameter,The accuracy of power quality analysis is improved.Secondly,according to the functional requirements of intelligent power meter,the hardware and software of the system are designed.Due to hardware of the system,the hardware solution based on ATT7022E and MK02FN128VLH10 is given.The circuit designs of system power module,main controller module,real time clock module,external extended FRAM memory module,RS485 communication module and human-computer interaction module are introduced in detail.The system software adopts modular design,the system main program,data acquisition program,remote communication program,LCD display program,external event alarm records prograxm,basic electric parameter calculation program and power quality analysis program based on windowed interpolation FFT algorithm are designed.At the same time,paper also analyzes the error that introduced in the design of hardware and software and the causes,and put forward the corresponding measures to reduce or eliminate the error,and design the software calibration process of the intelligent power.Finally,the module function and the whole machine test are carried out.The experimental results show that the designed intelligent power meter can monitor the power quality of power grid operation state.Through the error analysis of the experimental data,the measurement error of the voltage,current effective value,the 2-31 harmonic and the active power measurement of the intelligent power meter reaches 0.2%,and the error of reactive power measurement reaches 1%.At the same time,it has better temperature characteristics. |
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