Research On Intelligent High Voltage Wireless Phase Detector

Phase detection is to check whether the phase or phase sequence of power supply at both ends or loop network are the same by instrument or other method.In order to ensure the safe and reliable operation of the power grid,the three-phase circuit phase detection must be carried out before the grid connection of different power grids in power system,or before the substation and transmission line are put into use after reconstruction and maintenance.At present,the two-rod contact phase detector based on the principle of generalized AC bridge is relatively mature,and the non-contact phase detector based on the principle of electromagnetic induction has also been developed.However,there are still some problems,such as high contact voltage and complicated operation,strict requirements for phase detection synchronization,single detection voltage level and so on.Therefore,it is of great significance for operators to study a non-contact single-rod asynchronous high voltage wireless phase detector.Firstly,this paper analyzes the principles and error sources of four common high-voltage phase detection algorithms.By comparing the advantages and disadvantages of the four algorithms and combining with the actual phase detection requirements,a single-rod asynchronous phase detection algorithm is proposed,and the error correction is carried out for the problems of power grid frequency fluctuation and hardware zero drift.The modeling and Simulation of transmission lines with different voltage levels and flat capacitive electric field sensors prove that principle of non-contact induction is feasible and the phase detection distance is determined.The hardware and software function design and PCB debugging of the phase detector are completed.The phase detector is divided into reference terminal and test terminal.The reference terminal is used to induct the reference of power grid.The reference voltage signal is converted into a square wave with the same frequency by signal conditioning such as step-down limiting,voltage following,low-pass filtering and voltage comparison,and then transmitted wirelessly after real-time ASK modulation to provide a reference signal for phase detection for the test terminal;STM32F103VET6 is used as the main controller of the test terminal.By detecting the output of the phase detection signal conditioning circuit,it is obtained that the effective value of the induced voltage after precision rectification and the zero crossing time difference between the two waveforms.The functions of non-contact live judgment,frequency measurement and phase check are realized.The program development of mobile app intelligent phase detection management platform is completed successfully.Through low-power Bluetooth,it is realized that the wireless communication with the test terminal,the control of the phase detector to start phase detection and the real-time display and storage of results,which ensures the safety and convenience of operators.Three groups of experiments are carried out on the designed intelligent high-voltage wireless phase detector,including simulation test experiment,low voltage experiment and high voltage experiment.The simulation test experiment includes in-phase input experiment and complementary input experiment.The experimental results show that the design of software and hardware of the phase detector and mobile app intelligent phase management platform can meet the requirements of phase detection,and the inherent phase error of the system can be obtained at the same time.Low voltage experiment includes linearity experiment and low-voltage phase detection experiment.The experimental results show that the linearity of the flat capacitive electric field sensor is good,and it meets the requirements of non-contact phase detection.The actual power grid frequency fluctuation will not affect the measurement results,and the single-rod asynchronous phase detection algorithm is reasonable.The high voltage environment test results show that for the same voltage level and different voltage levels phase detection,the frequency error is within±0.03Hz,and the phase error is within±2.3~°,which meets the requirements of frequency measurement and phase resolution.In conclusion,the designed intelligent high voltage wireless phase detector can realize the non-contact single-rod asynchronous phase detection.The software,hardware and mobile app are working normally,achieving the expected purpose and requirements.