Anti Corona Test of Steam Turbine Generator

It is far from enough to verify the final completion of generator corona prevention by test only through theoretical design. Since raw materials and high voltage often bring great dispersion, the corona prevention structure and materials must be finally determined through a large number of test verifications.

Verification of raw materials: fiberglass tape for halo prevention of 600MW steam turbine generator is ordered from the fiberglass manufacturer according to special requirements. It is woven from waxed fiberglass instead of pretreated fiberglass. After entering the factory, there is no need to dewax, and the warp and weft density and twist of original yarn are changed to improve the impregnation of fiberglass tape.

Except for the twist, the other indexes of the domestic fiberglass tape meet and exceed the technical requirements of Hitachi. It can completely meet the needs of corona prevention of 600MW steam turbine generator.

The low resistance anti halo paint is used for one-time forming anti halo belt and brushing. The graphite is changed to acetylene black, and the formula is changed for many tests to obtain a satisfactory low resistance anti halo paint.

Its performance fully meets the domestic standards and the technical requirements of Hitachi.

High resistance anti halo paint High resistance anti halo paint is prepared with silicon carbide as the main raw material at home and abroad. Therefore, its performance mainly depends on the performance and content of cinnamon carbide in the anti halo paint. We conducted application tests on cinnamon carbide produced by different manufacturers, and changed the graphite conductive base previously used to acetylene black. Through a lot of tests and summaries, a high resistance anti corona paint suitable for 600MW steam turbine generator was selected.

The test proves that the high resistance anti corona paint is also the same. However, due to the small specific speed of ultra-high head pump turbine, the hydraulic thrust generated by the back pressure outside the runner and the small pressure difference at the pressure part at the runner side will change the total hydraulic thrust. Since it is difficult to accurately calculate the pressure distribution around the runner, including the transient operation state, Mitsubishi tries its best to maintain the balance of water thrust in the structural design of the real turbine from the perspective of pump turbine structure. Its characteristics are as follows: make the gap size between the back pressure chamber outside the runner and the side pressure chamber as same as possible.

The inner balance pipe (secondary balance pipe) and the outer connecting pipe (primary balance pipe) are set to balance the water pressure in the back pressure part and side pressure part of the runner.

When manpower is interrupted, the guide vane adopts the closing mode with less influence in the counter current area.

The change of water thrust before and after load rejection and input interruption is shown in. The field test results show that under all operating conditions, including normal operation and transient operation, excessive hydraulic thrust will not be generated and the operation is very stable.

Water thrust characteristics of pumping operation with generator output (MW) 4 Conclusion This paper introduces the design and test of ultra-high head pump turbine with the highest head in the world at present for the Kenokawa Pumped Storage Power Station in Japan. The field test results are basically consistent with the predicted values verified in advance and studied on the microcomputer, meeting the design requirements.

From the point of view of further pursuing economy, the technical problems of high head and high speed pump turbines are not all solved. In the future, research on improving analysis technology must continue to be carried out, which can fully meet the requirements of 22 kV motor corona prevention. Covering paint The covering paint for anti corona of 600MW steam turbine generator is basically the same as that of Hitachi, meeting the technical requirements.

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