In Ultra-High Voltage Direct Current（UHVDC）transmission system

optical fibers are used to replace the power lines to transfer the laser power to remote measurement modules.The laser power is then converted by photovoltaic cells to electric power to drive the sensors.Such an optic DC measurement system can realize isolation between high and low voltage circuit

insulation and anti-electromagnetic interference.Due to a high failure rate of the remote sensor

the operation principle

the structure and the weak point of the sensor are deeply analyzed.Based on the analysis

an improved DC measurement sensor is designed and developed.In the improved DC measurement sensor

the maximum power point tracking technique is adopted for the photovoltaic cell

and the circuit design of each module is optimized.These modifications not only improve the integration level of the modules but also the device performance.The on-site test results show that the measurement accuracy and power consumption of the improved sensor are better than those of the foreign sensor products.The designed sensor can improve the accuracy and stability of DC measurement systems.