Research on the Step Response Testing Technology of DC Measuring Device in VSC-HVDC

According to technical requirements for the step response of DC(direct current) current measuring device in the flexible DC transmission project, we studied the measurement requirements and methods for the key technical indicators of step response, including rising time, delay time, overshoot and stabilization time. We designed a step response test scheme consisting of signal generator, transconductance amplifier, precise coaxial shunt, high-precision clock synchronization device and step response verification system. Step delay time of transconductance amplifiers and precision coaxial shunts is approximately 1$\mu$s, rising time is approximately 1.5$\mu$s. Step response verification system adopted resampling noise reduction technique and Labview measurement technique, time resolution is less than 1$\mu$s. DC current measuring devices were tested by using the step response test scheme. According to the results, magnitude of step current, rising time of step source and data calculation method all affect the key technical indexes of the step response, the test scheme meets the step response test requirements of DC current measuring device with the data sampling rate of 100kHz and the step response time less than 60$\mu$s in flexible DC transmission engineering.