Enhanced on-site testing of DC current transformers using improved EMD filtering and high-precision synchronization

The DC current transformer, which forms the foundation of the high-voltage DC transmission system, must be designed rationally and have accurate field testing. This study examines the causes of the faults in the field test system for the DC current transformer and suggests a closed-loop test technique for the field that builds upon empirical modal decomposition (EMD) filtering. The technique uses an 18-bit high-precision A/D acquisition and the EMD algorithm to filter out harmonics, which greatly increases the measurement accuracy of the test system. It also realizes the synchronous acquisition of the standard source analog quantity and the measured digital quantity through the high-precision synchronization module, which solves the error caused by the delay. The test findings indicate that the enhanced system removes data with significant inaccuracies in the standard value 6250A test, bringing the measured value closer to the standard value. Furthermore, a step source system was built and its accuracy and feasibility were confirmed by experiments for the purpose of measuring the transient step response of DC current transformers. The enhanced test equipment performs exceptionally well in transient and steady state tests and is highly valuable for engineering applications.