Coordinated Control of Multiple HVDC systems for damping interarea oscillations in CSG

This paper describes part of our recent works on a project of China Southern Power Grid (CSG), which involves the simultaneous coordinated tuning of the three HVDC modulation controllers, with wide-area signals, in 2008´s CSG to damp interarea oscillations. Due to the modeling limitation of HVDC control loops in small signal stability analysis, previous works on similar projects of CSG strongly depended on trial and error method, which tests each set of controller parameters with time-domain simulation to observe how the controllers work. The paper induces a novel HVDC modulation model compatible with NEVA. Using the linearized system model and a hybrid stochastic nonlinear optimization algorithm, combined with genetic algorithm and simulated annealing algorithm, a strong nonlinear modal interaction phenomenon which is so called ´modal resonance´ is avoided. Furthermore, the parameters of the three HVDC modulation controllers are optimized simultaneously. Time domain simulations with NETOMAC validate the efficiency of the coordinated control scheme.