The Design Of Ultrasonic Detecting Circuit And Application On Partial Discharge

Partial discharge (PD) detection is an important measure to ensure and maintainthe normal operation of the power system. Electromagnetic and ultrasonic detection aretwo relatively advantage testing methods among existing PD detection methods. Due tothe low sensitivity of the sensor in the ultrasonic detection, a high detection sensitivityand battery-powered ultrasonic sensor in combination with low noise amplifier (LNA)and logarithmic detector is developed in this paper and its performance such assensitivity and gain have been tested. Compared with two separate electromagnetic andultrasonic sensors in traditional sound and electric PD location, a new method of PDlocation using ultrasonic associated with electromagnetic detection is analyzed anddeveloped, with which the detecting circuit is able to achieve the sound signal arrivaltime difference to position the PD points with less number of sensors and bring greatconvenience for PD on-site measurements. Finally, through the laboratory simulationand test, the sensor of ultrasonic and electromagnetic integration is able to be used forPD detection and position.The main work and results in this paper are as follows:1. Commonly used detection methods for PD and its development status arepresented focusing on the development status of ultrasonic detection and ultrasonic andelectromagnetic integration method. Analysis of the advantages and disadvantages ofthe two detection methods is given and the existence of the problem needs furtherresearch and development to determine the necessity for PD detection.2. Mechanism for ultrasound generated by PD based on the electromagnetics-mechanics-acoustics theory is described. The propagation characteristics and spectrumof ultrasound are presented. Combined with the characteristics of ultrasonic andrequirements for PD detection, the basic parameters of the optional ultrasonic sensor aregiven based on acoustic-electric conversion principles.3. Combined with LNA and the logarithmic detector amplifier technology, anultrasonic sensor circuit for PD detection is developed. Its circuit performance, specificparameters of the design, circuit schematics and PCB diagrams are given.4. A high detection sensitivity, battery-powered and ultrasonic and electromagneticintegration sensor based on ultrasonic circuits is developed by analyzing the principle ofultrasonic and electromagnetic integration. The circuit diagram and the entire structureof the sensor design are given. The sensor can detect the electromagnetic signals and ultrasonic signals at the same time and the time difference characteristics can also beachieved.5. The sensitivity and gain of the ultrasonic sensor have been tested throughapplying the testing pulse signals. With electronic ignition placed in metal cargocontainers in the laboratory to simulate the practical PD condition, the sensor ofultrasonic and electromagnetic integration has been tested and its availability in PDdetection and position is proved.