The Research On Dual CPU Power Quality Monitor

With the development of electric power system, the number of nonlinear loads in electric network is increasing, which makes nonlinear, instability and asymmetry of electric network more and more serious. Therefore, both power suppliers and power consumers take attention to power quality more and more. And it is very important for locating disturbance sources and improving power quality to monitor, record and analyze power quality real-timely and on-line.This dissertation firstly discusses the measurement methods of power quality parameters in detail, including RMS current and voltage, three-phase imbalance, four-quadrant power and harmonic, etc. Then the dissertation introduces the software and hardware of the devices. The device adopts the dual-CPU structure, and the two CPUs are DSP and ARM. DSP mainly collects data and calculates power quality parameters by its fast calculation ability. ARM is mainly in charge of the communication with computer and LCD display. In the aspect of software, FFT is adopted to implement harmonic calculation, and the embedded operation systemμC/OS-Ⅱand the embedded graphics interfaceμC/GUI are transplanted to S3C44B0X whose kernel is ARM7TDMI. The embedded operation system not only increases the system reliability but also simplify the development of application programs. Simultaneously, making use of the advantages ofμC/GUI such as concision, handsome, convenience and humanity, we can develop abundant human-machine interface information.At last, the hardware and software of the whole device are debugged. Through on-line test, the corrective power quality parameter data can be obtained. The device began to run in Yanjin from JAN, 2007. Practical running shows that the designed power quality monitoring device is stable and reliable and can meet the design requirements.