Typical Test Scheme and Application of Security and Stability Control System for UHVDC Project

The experimental research on the security and stability control system (referred to as SSCS) of UHVDC transmission project mainly involves the functional verification on information interaction between SSCS and UHVDC control and protection system, the fault criterion of DC converters, the calculation of DC power loss, and the coordinated control strategies such as generators/loads tripping or DC transmission power modulation after failures in DC system or N-2 faults in AC system, and other aspects. This paper analyzed the existing test methods for SSCS, then proposed a modular modeling method. This modeling method transformed the external system of the AC/DC hybrid network into REI nodes, and performed coherency-based dynamic equivalence on the sending-end generator groups. The modular design reduces the granularity of simulation calculations, improves the speedup ratio of parallel computing, and improves the efficiency of processors usage to meet demands for large-scale closed-loop testing on UHVDC system-level protection technologies including DC co-control and precisely machines tripping. Based on this modelling design, the function of DC control and protection system was simulated, the interface between RTDS and SSCS was realized, and the simulation and test platform for UHVDC SSCS was built on RTDS. The stability control strategies and the system function verification of Zhalute-Qingzhou ±800 kV UHVDC SSCS were carried out on the platform. The simulation and test results verified the effectiveness of the typical test scheme..