Node Flux-Linkage Synchronizing Control of Power Systems with 100% Wind Power Generation Based on Capacitor Voltage Balancing Scheme

TL;DR

The paper addresses the challenge of frequency and voltage stability in a power system with 100% wind power by introducing a capacitor-voltage-balancing scheme-based node flux-linkage synchronizing control (CVBS-based NFSCM). It treats inverters as flux-linkage sources and enforces auto-synchronization through DC-link capacitor dynamics, while employing a logic-based bang-bang funnel controller (LBFC) to cap fault currents. The approach yields self-synchronization of flux-linkage vectors, inertia-like responses, and elimination of DC components in inverter currents, with simulations showing improved transient performance and fault-current rejection compared to voltage-sourced approaches. This work provides a novel synchronizing mechanism for inverter-dominated grids and demonstrates practical benefits for systems with 100% renewable generation, suggesting pathways for future secondary regulation and storage optimization.

Abstract

This paper proposes a node flux-linkage synchronizing control method (NFSCM) for power systems with 100% wind power generation based on a capacitor voltage balancing scheme (CVBS). Different from the conventional grid-forming controllers, NFSCM is designed to regulate inverters as virtual flux-linkage sources. Auto-synchronization of flux-linkage vectors is achieved through the CVBS-based NFSCM. The mismatch among the angular frequencies of flux-linkage vectors is eliminated by regulating the tracking errors of DC-link voltages, which establishes a negative feedback between the output frequency and active power of the inverter. NFSCM is adaptive to weak and strong grids. It avoids the excitation inrush currents in the step-up transformer of wind power generators. It also eliminates the DC components of the three-phase currents, and avoids low-frequency oscillations in active power. In order to limit the short-circuit current of inverters, a logic-based bang-bang funnel control (LBFC) is designed to control the switches of inverter bridges when over-current is detected. LBFC is able to restrict various fault currents within an acceptable range within the shortest time. LBFC and NFSCM are designed to operate in a switched manner according to a state-dependent switching strategy. Time-domain simulations were conducted on a 100% wind power generation test system, and the performance of NFSCM and LBFC were investigated.

Figures (9)

• Figure 1: Layout of a test power system with 100% wind power generation.
• Figure 2: The control system of WPG$_{i}$.
• Figure 3: Topology of the three-phase full-bridge inverter.
• Figure 4: Schematic of the switching strategy between LBFC and NFSCM.
• Figure 5: Dynamics of WPG$_{1}$ and WPG$_{3}$ obtained in the case where a 400MW load was connected on load bus 9 at $t=2$s under the control of NFSCM ((a) Three-phase voltages measured on load bus 9 (b) Three-phase currents measured on generator bus 3 (c) Active power output of WPG$_{1}$ (d) Active power output of WPG$_{3}$ (e) Capacitor voltage of WPG$_{1}$ (f) Capacitor voltage of WPG$_{3}$).