Design And Implementation Of Intelligent Power Distribution Unit Based On Modularization

The power distribution network in our country is gradually presenting characteristic of complicated structure, and the original measurement equipment of power distribution network,such as DTU( Data Transfer unit), FTU(Feeder Terminal Unit) and so on, have been unable to meet the needs of construction of initiative power distribution network. Therefore, modular intelligent power distribution unit, assembled in the traditional switching station, ring main unit, miniature transformer and box-type substation, etc, was exploited. The equipment can not only complete the data acquisition and control which used to be done by the traditional DTU, but also add the phase measurement unit, and the new-type intelligent power distribution unit which can support some functions, such as power distribution network power flow active management and power distribution network security closed loop control was formed.As the power distribution network lacks of real-time accurate phasor information at present, data was often collected by each independent equipment, which always lacks of accurate time scale information. The data information of cross section can not be acquired at the same time, when the power distribution network was at working of power flow analysis,state estimation, closed loop operation, etc, so the precision of calculation result must be affected to a large extent. In this work, a new-type power distribution unit measurement device(modularization intelligent power distribution unit) was designed, which can solve the problem of lacking of accurate time scale information. Precision reached to 1 us clock information was acquired via GPS/BeiDo module, and frequency multiplicating of clock via FPGA, then high-speed collecting pulse was obtained, and ADC was triggered to make sure that information module has a high-precision clock and the error of the phase angle calculation was reduced. Whether phasor measurement unit of different measurement points can be completed, the problems are that how to reach the phasor measurement unit and frequency phasor measurement unit at different places among the measurement units in the system, and the keys to work out these problems are clock synchronization of each measurement point and frequency tracking measurement.In this work, combining with the characteristics of power distribution network in ourcountry,phasor measurement unit which was cost-effective and suitable for mass installation was developed. The modular intelligent power distribution unit was designed and mainly consisted of main control module, telemetry extension module, telecommand extension module and telecontrol extension module. The main module was made of ARM+FPGA architecture, and synchronous timing at different places of intelligent power distribution unit was accomplished through GPS module and communication module, and unified time scale of phasor measurement can be marked synchronously by employing this device. The data,obtained by telemetry module and telecommand module, was transmitted to main control module through MLVDS bus interface, and one-to-many communication mode was achieved and high speed SPI communication sequence was adopted between each module. Telemetry extension module can transmit sampling points rapidly by using SMV interface, which can ensure real-time of data and solved the throughput capacity of the data. Event information can be transmitted quickly, and reducing communication latency is contribute to control the real time of the power network state because of Telecommand extension module with GOOSE data transfer protocol. Telecontrol extension module can receive command made by ARM,control the closure of relay and perform control command.The modular intelligent power distribution unit, with the characteristics of easy installation, flexible allocation and low cost, etc, was exploited by using modularized designing concept in this work. Modularization of telemetry, telecommand and telecontrol can make the users flexibly configure to meet the needs of different collecting information.Connect through the slot between the modules, which external wiring work can be replaced.The device is capable of collecting the phase angle and amplitude of voltage and current and the general information of the electrical quantity by the third party test, and it is platform-designed, which is convenient for users to extend application and develop secondary.