Design Of Novel Current And Voltage Measurement System For Smart GIS

At present, the electromagnetic transformer has generally served as the device to measure current and voltage in Gas Insulated Switchgear (GIS), and its operation condition directly impacting on the safety and stability of the power system. As there are many shortcomings in this conventional device, it cannot satisfy the progress of GIS. Besides, the advent of novel sensors has made the substitution of novel sensors for the traditional transformers posssible. Combinning novel sensor in Smart-GIS is the greatest advantage of Smart-GIS.Based on this concept, this paper designed a new electronic current and voltage measurement system for a 220kV GIS.The design of the electronic current and voltage measurement system for GIS using Digital Signal Processor (DSP) is presented in which the measuring, protection, and communication are integrated. The system is composed of three parts: current signal processing unit, voltage signal processing unit and DSP unit. The novel line current and voltage sensors are well suited to the geometry of gas-insulated coaxial lines. Line current is measured by a Rogowski coil and a coaxial capacitor is used as line voltage sensor. The out signals of current sensor and voltage sensor are put respectively into current and voltage signal processing unit, which responsible for the analogue filtering, the analogue to digital conversion, interface to optical bus. DSP unit is the kernel of the system which is responsible for the control and communication with other PC through RS-485 plus MODEM. Measurement signal is transmitted by optical fibers, which is resistant to electromagnetic induction and noise. By using FPGA, the system has a simple and flexible structure which can reduce the number of optical fiber.The work finished in this paper is as follows:1) System's hardware program has been designed, include analogue circuit part, digital circuit part and other hardware circuit interface.2) Hardware logic of FPGA and CPLD devices in system has been designed with VHDL language.3)DSP's software of system has been designed, include DSP' s software as well as programs for serial communications between computer and DSP.