The Design Of Power Quality Monitor’s Management Unit

The power quality monitor (PQM) can provide information for power qualityassessment, and basis for directing the comprehensive control work of powerpollution to improve the power quality. However, domestic power quality monitorsgenerally have shortcomings of low performance indicators and user friendliness, lessperfect function and so on.According to GB/T19862-2005“general requirements for monitoringequipments of power quality”, the management unit of PQM based on ADC+DSP+MCU structure is deigned with MSP430as the core, including human machineinterface(HMI) module, data storage module, communication module, switch in andout interface, etc. The PCB wiring and anti-interference, safety and reliability of themanagement unit are studied.Firstly, this thesis analyses the power quality problems, points out the necessityof power quality monitoring, and introduces the current research situation of powerquality monitoring technology both at home and abroad. Referring to the nationalpower quality standards of our country, various power quality indicators measuringmethod is studied. Flicker measurement algorithm based on Nuttall window anddouble spectral lines interpolation FFT is put forward. These lay the foundation ofmanagement unit’s implementation.Secondly, based on the relevant national and industry standards, the requirementof PQM is analyzed and confirmed, and the structure diagram of PQM is proposed, aswell as the hardware circuit of PQM management, which is consists of HMI unit, datastorage interface unit, communication interface unit, import and exit unit, power unitand clock unit, is designed in the thesis.Thirdly, in the thesis, the main program flow diagram of PQM management isdescribed. Then structuralization and modularization are adopted in the design ofsoftware, which includes the design of the bidirectional communication managementbetween MCU and DSP, the HMI management, the upper computer management inthe basis of RS-485and the data storage management.Finally, the improvement of safety design method in PQM management isdiscussed. Hence, software and hardware are taken to ensure the reliability of thesystem. In the end of the thesis, the experiment results are given to verify the validity of the method.Experimental results show that PQM can meet the precision requirements ofpower quality parameters, provide user friendly interface and also guarantee thestability.