On the 24th November 2017, testing for the first 300MVAr large synchronous condenser for UHVDC projects, manufactured by the Harbin Electric Group, was completed. The testing report (see figures below) shows that the dynamic performance of the synchronous condenser meets the operational requirements of the State Grid Corporation of China (SGCC).
As investment in HVDC technologies continues and more and UHVDC projects are connected to the system, the need for reactive power support of the networks also becomes important. Cascading faults within the AC and the DC systems increase the threats of voltage instability and synchronism with the grid. Once an UHVDC station with large power capacity suffers an outage, the converter will receive a large amount of reactive power from AC system, which leads to major voltage drops and further cascading faults in the ac network. The large synchronous condenser will provide greater amounts of reactive power in the transient period to prevent voltage drop and help with the fast voltage recovery requirements in post-fault conditions.
The following picture show the HVDC performance after voltage drop with condenser and without condenser, the red one show the converter station with condenser.
At the time of writing, the synchronous condenser has been sent to both the Zhatelu and the Jiuquan 800kV UHVDC converter stations where it is being installed and commissioned for full testing. The installation of larger synchronous condensers with allow for new stabilization strategies in the grid when it comes into service.