Secondary Multi-Bus Voltage and Frequency Fault-Tolerant Regulation Control via Hierarchical Mechanism

A multi-bus voltage regulation strategy based on distributed fault-tolerant control is proposed in a microgird (MG). The strategy addresses the challenges posed by the presence of actuator partial loss of effectiveness (PLOE) and deviation faults in multiple distributed generators (DGs) communicating through a directed network. The concept of containment control is introduced in the multi-bus voltage regulation strategy. In this paper, the bus voltages are limited to a reasonable range while still allowing voltage differences between buses for efficient power flow. In addition, a hierarchical mechanism is proposed to divide the voltage fault-tolerant containment control problem into a cooperative control problem for virtual systems and a decentralized control problem for real systems. Notably, the mechanism avoids relying on global information about the directed communication network and specific quantitative details about the magnitude, frequency, and type of actuator failures. In addition, we devise a consensus-based control strategy to regulate the frequency and efficiently share active power among DGs. The strategy is thoroughly evaluated through comprehensive simulation experiments, demonstrating its effectiveness and performance in voltage regulation and fault management scenarios. Note to Practitioners—This paper aims to propose a fault-tolerant secondary control strategy for bus voltages and frequency. First, considering that the power flow between buses is based on voltage differences, the problem of regulating the bus voltages is transformed into a containment control problem for linear multi-agent system (MAS) containing unknown nonlinear dynamics. Next, we design a fault-tolerant secondary control strategy with hierarchical control. At the network layer, a fault-free virtual system with adjacency information is created and approximated with a neural network for nonlinear dynamics. In the physical layer, a decentralized adaptive tracking controller is designed to synchronize the virtual system with the existing system. This layering process decouples time-varying PLOE fault parameters and adaptive control gains under an asymmetric network, thus enabling fault-tolerant control of actuator PLOE faults and deviation faults in a fully distributed framework. In addition, the boundaries of the fault parameters can be unknown. A feasible strategy is provided for industrial applications.