Small-Signal Modeling of Off-Grid Integrated Energy System Considering Internal Disturbances

Abstract

The development of the integrated energy system (IES) has become a hot spot in the energy field. According to the existing research, less research focus on off-grid mode modeling, but it play an important impact in operation and control of the system. In this paper, small signal modeling of off-grid IES considering external disturbances is studies. First, a small-signal state space model for four sub-modules including inverters, networks, phase-locked loop (PLL) and loads is established on its individual reference frame. On this basis, according to the coordinate transformation and intermediate equations, a complete small signal model is established on a common coordinate system by connecting all the sub-modules. Moreover, the internal disturbances of IES such as loads disturbances is added in the small-signal model by assuming the virtual resistor and disturbance load current. The modular small-signal model proposed in this paper can greatly simplify the small-signal modeling of IES, and this small-signal model can also provide theoretical basis for the state and stability evaluation of the system under internal disturbance.