Improved coherency-based wide-band equivalents for real time digital simulators

Summary form only given. This paper introduces an approach which enables very large power systems to be modeled on real time electromagnetic transients (EMT) digital simulators. This is achieved using an improved wide-band multi-port equivalent, which reduces a large power network into a small manageable equivalent model that preserves wideband behaviors. The low frequency or electromechanical transients are captured with a Transient Stability Analysis (TSA) type electromechanical equivalent derived using coherency based reduction techniques. The high frequency behavior is accurately captured by placing in parallel with the TSA equivalent, a passive Frequency Dependant Network Equivalent (FDNE). The validity of the proposed technique is demonstrated by comparing the approach with detailed electromagnetic simulations of a modified version of the New England 39 Bus Test System that includes an HVDC infeed. The power of the method is demonstrated by the real-time electromagnetic transient simulation of a large 2300 bus 139 generator system.