Qingdao Sifang Bombardier railway transportation equipment Co., Ltd. uses RongxinXingye SVG (hereinafter referred to as subsynchronous oscillation suppressor) with subsynchronous oscillation suppression function. The primary topology of the site is as follows:

The subsynchronous oscillation suppressor supplies power to multiple modules through 27.5/0.5kV step-down transformer. By detecting the load harmonic current, the controller makes the module output the harmonic current with the same amplitude and opposite phase to the load harmonic current, so as to achieve the suppression of the grid side harmonic current, and moreover suppress the sub synchronous resonance of the locomotive.

Before and after the subsynchronous oscillation suppressor is put into operation, the field measurement results are as follows

1. Pantograph raising test of eight CHRi EMUs at the same time

When the subsynchronous oscillation suppressor is not put into operation, serious subsynchronous oscillation occurs in the power grid, and the locomotive can not work normally (below left figure). When the subsynchronous oscillation suppressor is put into operation, the grid voltage and current have no obvious fluctuation, and the locomotive works normally (below right figure).

2.13 CRHi EMUs pantograph raising test at the same time

When the subsynchronous oscillation suppressor is put into operation, the voltage and current of the power grid and the waveform of the oscillation suppressor are recorded, and there is no obvious fluctuation of the power grid voltage and current.

To sum up, when the subsynchronous oscillation suppressor is not put into operation, serious subsynchronous oscillation will occur in the power grid when 8 CRHi EMUs are subjected to pantograph raising test at the same time, leading to locomotive failure. When the oscillation suppressor is put into operation and 13 CRHi EMUs are tested with pantograph rising at the same time, the grid voltage and current have no obvious fluctuation and the locomotive works normally. Therefore, the subsynchronous oscillation suppressor can effectively solve the subsynchronous oscillation problem of locomotive traction transformer.