Aggregating a Renewable Power Station Into a Single Generator for Quick Small-Signal Stability Evaluation

In this paper, a single-generator aggregated model (SGAM) of a renewable power station (RPS) is derived for the quick especially simulation-based evaluation of small-signal stability. The common scenario that the generators in the station are of the same type and from the same supplier is considered. However, the steady-state operating points (SSOPs) of the generators and the network topology can be arbitrary. Based on the derivation results, by changing the SSOP of the generator in the aggregated model or the reactance of the connection line, SGAM of the RPS under different SSOPs and network topologies can be built. Thus, the SGAM is simple in utilization. In the meanwhile, efficiency of the small-signal stability evaluation of an RPS can be much improved when considering various SSOPs by using the SGAM. Furthermore, the derivations reveal the parameter relationship between the SGAM and the original station. Based on this, conclusions drawn about the small-signal stability of a single grid-connected generator can be developed to an RPS. Finally, effectiveness of the SGAM proposed in the small-signal stability analysis is examined and validated based on three example RPSs, including a PV station, a DFIG wind farm and a PMSG wind farm.