[ Instrumentation Network Instrument R & D ] On November 15th, China Electric Power Research Institute Co., Ltd. completed a series of DC transformer transient test equipment tests, marking the successful development of this series of equipment, filling the gap in DC transformer transient test detection equipment.
Compared with AC transmission systems, DC transmission systems have higher requirements for the response speed and frequency bandwidth of control and protection signals, which means that the transient characteristics of DC transformers are more demanding. Regarding the transient characteristics and tests of DC transformers, the International Electrotechnical Commission (IEC) and China's power industry have formulated corresponding regulations. However, due to the lack of corresponding test and detection equipment, the transient characteristics test of DC transformers cannot be carried out normally, which lays a hidden danger for the safe and stable operation of DC transmission systems.
DC transformers are mainly used to measure large DC currents. They are also used as current feedback, control and protection components in rectifier systems. Compared with the shunt (see ammeter), it has low power loss and isolation. The circuit of common DC current transformer is shown in the figure. In the figure, A and B are two identical but independent cores. A large DC current I1 flows through the two primary windings (that is, the lead-through wire in the figure, which is equivalent to the primary N1 = 1 turn). The secondary windings on the two cores are N2 turns, connected in series with opposite polarities, and exchanged by a sine wave. Power supply.
The series of DC transformer transient test equipment developed by the Chinese Academy of Electrical Sciences includes the DC current and voltage transformer step response test system, and the DC current and voltage transformer wideband characteristic test system. Among them, the DC current transformer step response test system has a step test current amplitude of 3,000 amps, a pulse width of more than 10 milliseconds, and a rise time of less than 10 microseconds, which effectively solves the problem of step response test of DC current transformers.
In addition, the step response test system of the DC voltage transformer has a step test voltage amplitude of 200 kV, a pulse width of more than 10 milliseconds, and a rise time of less than 10 microseconds, which can be used for the step response test of DC voltage transformers; DC current transformers The wide-band test current amplitude of the wide-band characteristic test system of the converter reaches 600 amps and the frequency range is 50 to 3000 Hz. It provides equipment for the wide-band characteristic test of the DC current transformer; the wide-band test voltage amplitude of the wide-band characteristic test system of the DC voltage transformer reaches 10 KV and frequency range is 50 ～ 3000 Hz, which can be applied to the wide-band characteristic test of DC voltage transformer.
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