Study On 10kV/35kV Electronic Voltage/Current Transducers

Voltage transducer and current transducer are the basic measurement instruments forenergy measurement and relay protection in the electric power system. With the increasingdemand for digitization and automation in the electric power system control and protectionetc. , conventional electro-magnetic CT/VT transducers show several unsolvable drawbacks,and could not satisfy the requirement of the modern power system any more. At present,people began to show more interests on new electronic voltage/current transducers, whichare based on electronics, micro-computer and fiber communication techniques. Based on the analysis of current development of electronic voltage/current transducersand presently available techniques, the resistor-divider voltage transducers and theRogowski-coil current transducer was chosen for our electronic voltage/current transducer.The main content of this thesis is listed below: 1. A high voltage high resist thick film resistor was chosen for its stability andsuitability for medium voltage power network. The error source of the resistor divider wasanalyzed, and the shielding was designed for it accordingly. Sample transducers of 10 KVand 35 KV were made. 2. The current transducer insulation structure was designed for medium voltageapplication. Multiple sample transducers of rated voltage 10KV,rated current 600A; orrated voltage 35KV,rated current 1250A/2000A were made. 3. There was once a limitation on the ratio of the framework radium to the sectionalwidth of the Rogowski Coil. In this thesis, such limitation was proved to be not necessaryaccording to the working principle of the Rogowski Coil. And this was validatedtheoretically and experimentally. 4. The secondary circuit was designed to be compatible with the digital relayprotection for medium voltage switch cabinet application. EMC measures were taken intoconsideration. In March 2004, our resistor divider voltage transducer samples of rated voltage 10KVand 35KV passed the type tests in Wuhan Institute of High Voltage. The 10KV samplepassed all tests, the precision is rank 0.2, and it is the first resistor divider voltage transducerin China that has passed authorized tests. The precision of the 35KV sample is rank 0.2, andthe sample passed the power frequency withstand test, the partial discharge test and thepower-frequency withstand test for low voltage components but without the IIlightning-impulse test. So we will go on to improve the 35KV sample and get it ready forthe lightning-impulse test. The Rogowski Coil current transducer sample passed the linearity and angular errortests in our lab, the precision is rank 0.2. We will go on to improve its insulation structureand get it ready to pass the authorized experiment.