Research on the Mechanism of Network Energy Participation in the Dynamic Process of the Converter Interfaced System

With the increasing penetration of renewable energy sources, oscillation issues with unclear mechanisms have frequently emerged in power systems. Due to the distinct characteristics of renewable energy generation equipment compared to traditional synchronous generators, substantial research has been conducted in this area. However, the network, as another integral component of the system, also plays a critical role in system stability, which cannot be overlooked. System oscillations are fundamentally a result of energy exchange between storage elements. Based on this understanding, this paper investigates the mechanisms of network energy participation in the dynamic processes of the system. First, the operating principle of the converter-interfaced system is analyzed. Then, from the perspective of the “unbalanced forces-matter-motion state”, the dynamic processes of the system are reinterpreted, and the internal mechanisms of device and network motion are established. Next, based on the system power flow, a comparison is made between steady-state and dynamic processes to analyze the energy storage mechanisms of both device and network. Finally, closed-loop simulations are conducted to analyze the evolution of various physical quantities and network’s energy exchange behavior during the network’s involvement in the system’s dynamic process, validating the consistency with the previous mechanistic analysis. Additionally, the influence of network inductance variation on the energy exchange behavior during the system’s closed-loop dynamic process is studied. The results show that with increased network inductance, the energy exchanged by the network in the dynamic process becomes larger, significantly increasing the risk of system instability. This paper establishes a general understanding of network energy participating in the dynamic process of the system, which provides a basis for analyzing the oscillation mechanism of the system.