Zhang Yuekui

Design of Space Charge Density Measuring Device Based on Air Filtration Methods

To measure space charge density around UHVDC transmission lines, a measuring device is developed based on air filtration methods. The device, which uses STM32 microcontroller as the core controller, collects charged particles in the air by adsorption material. Through the charge to voltage converting circuit, charges absorbed are transferred into a voltage signal and are collected by microcontroller. Space charge density in the region is calculated combining the air flow measured by hot-wire anemometer. To reduce the measurement error, the equivalent circuit model of air filtration methods is analyzed. The source of error is analyzed and methods to reduce error are obtained. The device is used in ultra high voltage DC test base to measure the space charge density under UHVDC transmission lines. The results show that there are similar tendency compared with the theoretical value of bipolar transmission lines. The feasibility and availability of the device is verified.

Design of Distributed Current Source System Based on CAN Bus

A current source system based on CAN bus was designed. The system is used for distributed control of the current source. The current source module of the system is controlled by the AT89C52 micro controller, and the output current is bidirectional and adjustable. The current source module has high linearity and stability. The system operates simply, and it has high reliability. The system provides a practical solution for situations where bidirectional current source is required.