Embedded System Real Time Data Acquisition System Using FPGA Technology for Detection and Counting of PD Signal from PICO Pulse Generator

Abstract

The FPGA (Field Programmable Gate Array) technology is widely used today for signal processing and control owing to its fast digital processing capabilities. Using this, a test-bed high-speed data acquisition system that combines a commercial FPGA board (ML405) with the ADC in PIC micro-controller 16F877A that has 8 bit in resolution, sampling rate of 20 MS/s and bandwidth of 10 MHz for counting very high speed transient signals has been developed and successfully tested in the lab. This system enables direct measurement and counting of the transient signals at 50-100 ns pulse width at a sampling frequency 20MHz from Pico pulse generator as simulator of Partial Discharge signals on the site. All the results are shown to proof the concept for detecting partial discharge with pulse width of 5 ns in high power underground cables. The advantage of this system is that it can easily be deployed and count simulated Partial Discharge signal without the use of an oscilloscope and PC. The work in this paper comprises of using VHDL programming in FPGA to capture and discriminate the high-speed transient signals that has been digitized by the ADC in PIC micro-controller. In implementation of the test in the laboratory for the detection circuit, it is shown that it can detect the amount of impulses quite accurately. This is shown in PD detector system whereby LCD reads 84,746 impulses per second when it was set at 84.746 KHz repetitive using Pico pulse generator. The result show that the output peak detector can detect peak signal from input signal of the ADC when the pulse width of PD signal more than 30 ns using the ADC of the PIC Microcontroller 16F877A. Several features such as counting and discrimination between pulses are integrated in the system are also shown. This concept will be used in the future to detect real partial discharge generated in high power underground cables in the field.