Integrated Measurement Unit For Synchronous Phasor And Power Quality In Distribution Network

With the extensive access of distributed power supplies,traditional distribution networks develop to active distribution networks with both power and loads,and the operating characteristics have undergone tremendous changes.Renewable energy sources,such as wind power and photovoltaics,are widely connected to the distribution networks through power electronic equipment,making the distribution network present a dynamic multi-power two-way power flow operation mode,the intermittent and fluctuating nature of distributed power sources lead to dynamic behaviors of power grids more complex.In addition,ubiquitous power electronic devices and non-linear loads become the source of harmonics in the distribution network,seriously affecting the quality of power supplies.To meet the challenges of the active distribution network synchronous measurement,based on the PMU Light,this paper developed an integrated measurement unit,monitoring synchronous phasor and synchronous power quality in distribution networks at the same time.Synchronous phasors,synchronous harmonic parameters and synchronous waveforms can be used to provide new data support and decision-making solutions for advanced applications such as distribution network fault location and harmonic source location.The device is small and low cost,and can be widely installed in the distribution network,which is of great significance for the comprehensive synchronous monitoring of the power grid.The specific research works and results are as follows:(1)A sampling waveform reconstruction algorithm integrating phasor measurement and power quality measurement is proposed and adopted.The algorithm can reduce the measurement error caused by non-synchronous sampling and greatly improve the measurement accuracy of amplitude,phase and frequency.At the same time,the fundamental voltage amplitude after phasor calculation can be directly used to calculate the harmonic parameters and the three-phase unbalance degree,which significantly reduces the amount of calculation.(2)This paper designed the device hardware platform,implemented an efficient integrated measurement algorithm software,and made a prototype.Combining the common architecture of the PMU and power quality monitoring device at the hardware level,a suitable hardware platform was selected and designed,and the DSP+ARM+FPGA combination was adopted to form an open modular hardware structure system,facilitating the device upgrade.At the same time,the coordination between high-performance processors enables real-time sampling,calculation,communication,and liquid crystal display,greatly improving data processing speed.At the software level,this paper designed and coded FPGA program,DSP program and ARM program based on Linux system,focusing on optimizing and debugging the integrated measurement algorithm program in DSP.(3)The measurement accuracy of the new device was fully tested,the prototype device was deployed in Yangzhou distribution network.The device meets industry standards in terms of networking mode,synchronous timing mode,input hardware interface,and chassis design.According to the relevant international and national standards,the measuring accuracy of the device was tested.Testing results shows that the accuracy of the device meets the requirements of the standard.In the pilot application of the device,the machine was installed at the lOkV substation and photovoltaic grid-connected point,the synchronized measurement data transmitted back was analyzed.