Dc Insulation Monitoring System Research

With the constant expansion of electricity networks, the control and signal system,relays and automechanisms of power plant and substation were supplied the working power supply of DC system.It is important that the safe operation of the protection of power system.In order to overcome these disadvantages of the insulation detection of DC system now, it analysis the reasons for the DC system ground fault. It also describes the dangers of the DC system grounding system, and proposes appropriate countermeasures. It is proposed a method which is based on the ultra-double-low frequency injection. It makes a specific analysis of the overall program design, such as hardware design and software design ideas and the main program.It uses the STM32as the core of the system control chip, and equips with a3.2inches in65536colors industrial touch screen. The DC insulation monitoring detection system hardware platform contains the ultra-double-low frequency signal source module, the ground signal detection module, the conditioning circuit module and the communication of host computer module, and the host and lower computer program. It describes how to use these circuit elements, such as hall current sensor, digitally controlled programmable-gain instrumentation amplifier, precision optical isolator, low noise operational amplifier and other circuits. They can effectively inhibit and eliminate the noise and interference of the analog and digital systems. They can also improve the measurement accuracy.After testing the system and obtained experimental results, when the DC system fails, you can detect grounding resistance range of200Ω～200KΩ The resistance of resolving capability is150Ω. When the DC system fails, you can detect grounding capacity range of1uF～500uF。The capacity of resolving capability is0.5uF.The experiment results indicate that the apparatus has high accuracy.