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A new finite‐time secondary voltage and frequency restoration scheme for an islanded microgrid (MG) is proposed in this study. All distributed generators (DGs) do not have access to the voltage and frequency reference value which makes their control more challenging. Therefore, a finite‐time Information Discovery Scheme (IDS) is incorporated into the distributed secondary control scheme. The IDS provides local estimates of the global references of voltage and frequency for DGs in finite‐time, and distributed control scheme uses this information to restore the voltage and frequency of MG to their reference values while accurately sharing the active power among the DGs in finite‐time. The proposed control scheme is implemented on a sparse communication network and obviates the need for a central controller thereby reducing the risk of single‐point‐failure. The proof for finite‐time restoration and restoration time upper‐bound are derived using Lyapunov theory. The effectiveness of the proposed control scheme is verified through simulation of an MG test system in MATLAB/SimPowerSystem environment for sudden load variation and time‐varying communication topology. The proposed control scheme supports plug and play capability and exhibits better convergence performance and disturbance rejection than the asymptotic controller based on neighbourhood tracking error.

This study proposes a secondary voltage and frequency control scheme based on the distributed cooperative control of multi-agent systems. The proposed secondary control is implemented through a communication network with one-way communication links. The required communication network is modelled by a directed graph (digraph). The proposed secondary control is fully distributed such that each distributed generator only requires its own information and the information of its neighbours on the communication digraph. Thus, the requirements for a central controller and complex communication network are obviated, and the system reliability is improved. The simulation results verify the effectiveness of the proposed secondary control for a microgrid test system.

In this paper, the voltage regulation in power systems is addressed from the perspective of the modern paradigm of control logic supported by phasor measurement units. The information available from measurements is used to better adapt the regulation actions to the actual operation point of the system. The use of the online measurement data allows for identifying the sensitivity matrix and for improving the regulation performances with respect to the fast load variations that increasingly affect modern power systems. With the aim of estimating the sensitivity matrices, a preliminary action is necessary to reconstruct the phases of the network voltages, which are assumed not to be provided by the phasor measurement units. This allows for obtaining a model-free adaptive control method. It is then shown how the regulation problem can be formulated in terms of a linear quadratic Gaussian problem, properly considering the load modeling in terms of the stochastic Ornstein–Uhlenbeck process. This control strategy has the advantage of avoiding dangerous oscillations of power flows, as demonstrated through the results of some simulations on a classical test network. Particularly, the advantage of the proposed approach is shown in the presence of different levels of load disturbances.

Although voltage regulation in distributed generation (DG) in offshore wind power systems has been deeply studied, information on the global communication network structure and high communication bandwidths still remain key factors restricting the integration of a high proportion of new energy sources. In order to achieve precise voltage regulation while reducing communication, this paper proposes a fully distributed dynamic event-triggered secondary voltage restoration control for offshore wind power systems. Firstly, the nonlinear system model is switched to the linear second-order multi-agent system (MAS) by feedback linearization. This is a crucial step for the subsequent research. From there, a fully distributed voltage restoration control strategy is proposed, which utilizes adaptive event-triggered protocol. The proposed protocol operates independently of global information. Finally, the effectiveness of the control protocol is verified through simulation.

Sustainable energy-based generation systems, such as photovoltaic and wind turbine generation systems, normally adopt inverters to connect to the grid. These power electronic interfaces possess the characteristics of small inertia and small output impedance, which create difficulties to stabilize the voltage and frequency of a distributed power source. To deal with this problem, a Virtual Synchronous Generator (VSG)-based inverter control method is presented in this paper by introducing virtual inertia and damping coefficient into the control loop to emulate the dynamic behavior of a traditional synchronous generator. Based on this VSG control method, a three-layer hierarchical control scheme is further proposed to increase the control accuracy of the voltage and frequency in a VSG-based distributed generation system with parallel inverters. The principle of the VSG control method, the system stability analysis, the design process of the hierarchical control structure, and the frequency/voltage secondary regulation processes are all specified in this paper. Finally, some numerical simulations are carried out and the effectiveness of proposed control scheme is verified by the simulation results analysis.

This paper presents the application of fuzzy logic PID secondary voltage control to the Egyptian power system model. The study included tertiary voltage control, Wide Area Measurement System (WAMS) configuration, a selection of pilot buses, and fuzzy logic PID secondary voltage control to improve the system performance. The secondary voltage control was applied using a fuzzy PID coordinated controller, a reactive power integral controller, Automatic Voltage Regulators (AVRs), and regional generators. The tertiary voltage control was implemented based on the optimal power flow to maximize the reactive power reserve. A novel optimization technique is presented to select pilot buses based on different operating conditions and compared to other techniques. The optimal WAMS configuration included the best allocation of Phasor Measurement Units (PMUs), Phasor Data Concentrators (PDCs), and the required communication infrastructure considering geographical regions with minimum cost. The Egyptian power grid considering 500/220 kV level is simulated by using DIgSILENT software to perform static and dynamic analyses, while the WAMS optimization problems and fuzzy logic PID controller design are performed by employing MATLAB software.

This paper presents techniques for the application of tertiary and secondary voltage control through the use of intelligent proportional integral derivative (PID) controllers and the wide area measurement system (WAMS) in the IEEE 39 bus system (New England system). The paper includes power system partitioning, pilot bus selection, phasor measurement unit (PMU) placement, and optimal secondary voltage control parameter calculations to enable the application of the proposed voltage control. The power system simulation and analyses were performed using the DIgSILENT and MATLAB software applications. The optimal PMU placement was performed in order to apply secondary voltage control. The tertiary voltage control was performed through an optimal power flow optimization process in order to minimize the active power losses. Two different methods were used to design the PID secondary voltage control, namely, genetic algorithm (GA) and neural network based on genetic algorithm (NNGA). A comparison of system performances using these two methods under different operating conditions is presented. The results show that NNGA secondary PID controllers are more robust than GA ones. The paper also presents a comparison between system performance with and without secondary voltage control, in terms of voltage deviation index and total active power losses. The graph theory is used in system partitioning, and sensitivity analysis is used in pilot bus selection, the results of which proved their effectiveness.

This paper presents secondary voltage control by extracting reactive power from renewable power technologies to control load buses voltage in a power system at different operating conditions. The study is performed on a 100% renewable 14-bus system. Active and reactive powers controls are considered based on grid codes of countries with high penetration levels of renewable energy technologies. A pilot bus is selected in order to implement the secondary voltage control. The selection is based on short-circuit calculation and sensitivity analysis. An optimal Proportional Integral Derivative (PID) voltage controller is designed using genetic algorithm. A comparison between system with and without secondary voltage control is presented in terms of voltage profile and total power losses. The optimal voltage magnitudes at busbars are calculated to achieve minimum power losses using optimal power flow. The optimal placement of Phasor Measurement Units (PMUs) is performed in order to measure the voltage magnitude of buses with minimum cost. Optimization and simulation processes are performed using DIgSILENT and MATLAB software applications.

This paper deals with the problem of voltage and frequency control of distributed generators (DGs) in AC islanded microgrids. The main motivation of this work is to obviate the shortcomings of conventional centralized and distributed control of micro-grids by providing a better alternative control strategy with better control performance than state-of-the art approaches. A distributed secondary control protocol based on a novel fixed-time observer-based feedback control method is designed for fixed-time frequency and voltage reference tracking and disturbance rejection. Compared to the existing secondary microgrid controllers, the proposed control strategy ensures frequency and voltage reference tracking and disturbance rejection before the desired fixed-time despite the microgrid initial conditions, parameters uncertainties and the unknown disturbances. Also, the controllers design and tuning is simple, straightfor-ward and model-free.i.e, the knowledge of the microgrid parameters, topology, loads or transmission lines impedance are not needed in the design procedure. The use of distributed control approach enhances the reliability of the system by making the control system geographically distributed along with the power sources, by using the neighboring DGs informations instead of the DG’s local informations only and by cooperatively rejecting external disturbances and maintaining the frequency and the voltage at their reference values at any point of the microgrid. The efficiency of the proposed approach is verified by comparing its performance in reference tracking and its robustness to load power variations to some of the works in literature that addressed distributed secondary voltage and frequency control.

This study presents a novel coordinated secondary voltage control (CSVC) and reactive power management scheme for efficient utilisation of distributed energy resources in a smart distribution network. The proposed controller is developed to achieve efficient voltage regulation and to maximise the dynamic reactive power reserve in a distribution network to react during system contingencies. The simulated distribution system, including an on-load tap changer (OLTC) and distributed energy resources, is implemented using PSCAD/EMTDC. The CSVC is designed to provide slow and medium speed responses, using low-pass filters for OLTC and diesel generators, respectively, and a fast response by utilising inverter-based distributed energy resources. Therefore it applies a control strategy with different bandwidth dedicated by the decentralised voltage controllers and reactive power management scheme. The CSVC is used to enhance the bus voltage control by utilising the reactive power loading capabilities among distributed energy resources and on-load tap changers of the substation transformer. A comprehensive simulation has verified the superior performance of the proposed coordinated secondary voltage control with the reactive power management scheme for enhancing the voltage profile and the fault ride-through capability, ensuring higher dynamic reactive power reserves in a distribution network, and improving the transient stability margin.