Back-to-back test method of VSC-HVDC MMC valve stable state operation test

The invention provides a back-to-back test method of a VSC-HVDC MMC valve stable state operation test. Devices used in the method comprise a rectification side, an inversion side and a supporting capacitor. The rectification side and the inversion side are in parallel connection at two sides of the supporting capacitor respectively to form a back-to-back circuit. Through controlling submodules of valve modules of the rectification side and the inversion side, stable state operation voltage, current and heat intensity equal to actual condition are obtained. According to the invention, the rectification side and the inversion side share a power supply, active power emitted by the power supply returns to the power supply, a power supply capacity requirement is reduced at the most; the valve modules of the invention are selected from an actual engineering, a test circuit operation principle and a control strategy have high similarity with MMC in the actual engineering, and necessary effective valve operational reliability investigation means and control strategy verification environment are provided for the MMC before investing in practical application.