340 / 2022-03-15 16:06:37

A Hybrid Control Strategy Based on Frequency Trajectory Planning and Virtual Synchronous Machine (VSG) to Support Frequency Stabilization.

Frequency stability, frequency trajectory planning, virtual synchronous machine, anti-interference ability, signal stability analysis.

In order to achieve carbon neutrality and energy structure transformation, new power system needs to be constructed urgently. With the development of new energy in the energy production side, the high proportion of new energy and high proportion of DC power transmission will lead to the reduction of the inertia damping level of the power grid, which could worsen the dynamic characteristics of the power system and challenge the frequency stability. How to realize short-term frequency stability is one of the most urgent security and stability problems in constructing new power system. To solve this problem, this paper proposes a hybrid control strategy based on frequency trajectory planning and virtual synchronous machine (VSG) to support frequency stabilization. Firstly, the virtual inertia damping scheme is analyzed, and the control model of the virtual synchronous machine is established. Secondly, this paper analyzes the idea of frequency trajectory planning control strategy, and introduces frequency change rate and frequency modulation cost index into the control model of virtual synchronous machine to improve the anti-interference ability of virtual synchronous machine. When the interference is small, the frequency offset is small, and the system is in a relatively safe area, the virtual synchronous machine can provide enough virtual inertia and damping. When the interference is large, the frequency offset has the risk of crossing the boundary. In this case, the frequency trajectory planning and the virtual synchronous machine cooperate to control, forcing the system frequency to quickly and smoothly recover to the safety zone on the planned trajectory. Then, the stability of the control strategy is determined by small signal stability analysis. Finally, the reliability and superiority of the proposed control strategy are verified by simulation comparison.