Research Of Electric Power Quality Monitoring Device In Small Hydropower

Owing to the restriction of operating costs, the level of electrification and automation ofsmall hydropower in China is so low that brings about serious power quality problems ingrid-connected power generation, such as a high deviation of supply voltage and frequencyinstability and a higher harmonic content. The research of intelligent power qualitymonitoring system for small hydropower is still in the initial stage in China. Now, statisticalpower meter is widely used to monitor the level of power quality, although a series ofdrawbacks such as single monitoring index and low intelligentize still exists. In this paper, anintelligent power quality monitoring devices is designed with ingeniously structure and stableperformance according to the actual situation of small hydropower. Specific content includethese points.(1) According to the actual situation, define the power quality indicators which need tobe monitor, such as voltage deviation, frequency deviation, harmonic content, valid values ofthe voltage/current, active power, reactive power, apparent power, power factor and otherbasic power parameters are included in the monitoring indicators.(2) According to the application requirements and the actual conditions, choose the bestdesign options and built the overall framework of the system. Ultimately determine theoverall design of DSP as the core of the system.(3) A modular design concept is adopted in the hardware design of entire system,including analog signal conditioning, data acquisition, peripheral communication and otherhardware modules. Firstly, switch the high amplitude strong signal to a reasonable range fordata acquisition module acquisition through signal conditioning modules. Secondly, samplingdiscrete data is sent via parallel data bus to the DSP to do the data processing. And then, theenergy indicator parameters after calculated transmit to a PC via serial communication forfurther research. According to the actual requirements of small hydro electric power qualitymonitoring device, select the ADS8364as data acquisition core chip, to achieve accurateacquisition of the three-phase voltages and three-phase current at the same time. Also, selectTMS320F2812as the core of the system to achieve the control of the various functionalmodules, as well as real-time data processing.(4) Then goes for the design of software on the basis of hardware of small hydro power quality monitoring system. Data acquisition software modules use blocking way in theinterrupt service routine, and other program modules use an infinite loop way in the mainprogram loop. Software models of data processing use time domain analysis and frequencydomain analysis to dispose power quality index. C programming language is used in thealgorithm about software design and time region analysis of function model which is easy todebug and maintain. Frequency-domain analysis (FFT) adopt a hybrid programming methodof C programming language and assembly language, which promoting the speed of dataprocessing and guarantee the processing of data in time.(5) A functional testing about the entire system is done after the completion design of thehardware and software. Firstly, commissioning of various functional modules, and then testthe whole system in the simulation experiments scenes. The comparative analysis of testresults compare to standard values show that the design thought of small hydro power qualitymonitoring device in this paper is correct, with security and accurate hardware circuit andreliable stability of software algorithm is. It can achieve the requirements of the-phase ACpower quality monitoring.