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The direct current (DC) microgrid is one of the key research areas for our advancement toward carbon-free energy production. In this paper, a two-step controller is designed for the DC microgrid using a combination of the deep neural network (DNN) and exponential reaching law-based global terminal sliding mode control (ERL-GTSMC). The DC microgrid under consideration involves multiple renewable sources (wind, PV) and an energy storage unit (ESU) connected to a 700 V DC bus and a 4–12 kW residential load. The proposed control method eliminates the chattering phenomenon and offers quick reaching time by utilizing the exponential reaching law (ERL). In the two-step control configuration, first, DNNs are used to find maximum power point tracking (MPPT) reference values, and then ERL-based GTSMC is utilized to track the reference values. The real dynamics of energy sources and the DC bus are mathematically modeled, which increases the system's complexity. Through the use of Lyapunov stability criteria, the stability of the control system is examined. The effectiveness of the suggested hybrid control algorithm has been examined using MATLAB simulations. The proposed framework has been compared to traditional sliding mode control and terminal sliding mode control to showcase its superiority and robustness. Experimental tests based on the hardware-in-the-loop (HIL) setup are then conducted using 32-bit TMS320F28379D microcontrollers. Both MATLAB and HIL results show strong performance under a range of environmental circumstances and system uncertainties. [ABSTRACT FROM AUTHOR]

This paper addresses the escalating need for low-carbon solutions and discusses the integrated control system for the electric-hydrogen DC microgrids. A multi-time scale control mechanism for the DC microgrid is proposed, which aims to enhance its adaptability and scalability. The proposed multi-time control scheme comprises two control layers. The system-level control layer utilizes optimization to address economic issues and carbon trading, aiming to minimize operational costs and carbon emissions in the microgrid. The local-level control layer incorporates an advanced nonlinear control method based on the exponential reaching law-powered terminal sliding mode control (ERL-TSMC) for accurate tracking capabilities at the local-level and to handle dynamic control challenges in real-time. Furthermore, an event-triggered control mechanism is introduced to reduce considerable control efforts while guaranteeing system robustness under various disturbances. Both simulations and hardware experiments demonstrate that the proposed control method guarantees efficient low-carbon operation, achieving a significantly lower average carbon intensity of 0.19 kg CO 2 /kWh. Additionally, it exhibits robust performance at the local-level, with a steady-state error of only 0.03%. • A novel multi-time scale control strategy for electric-hydrogen DC microgrid is proposed. • System-level energy management that optimizes costs and carbon emissions is discussed. • Local-level event-triggered exponential reaching law based terminal sliding mode control is proposed. • The proposed control structure promises rigid DC bus voltage and low-carbon operation. • Real-time processor-in-the-loop (PIL) tests are performed to verify the simulation results. [ABSTRACT FROM AUTHOR]

Rapidly depleting oil and natural gas resources, global warming issue, and depletion of fossil fuels are motivating the development of alternative technology for vehicular systems. Thus, an increasing number of studies have been conducted on fuel cell electric vehicles (FCEVs). This paper proposes a modeling and nonlinear control for hybrid energy storage system (HESS) in FCEVs. HESS consists of fuel cell (FC) as the main source and battery and ultracapacitor (UC) as secondary sources. Each source is connected to DC bus via DC-DC converter: FC is connected to DC bus via boost converter, while battery and UC are connected to DC bus via buck-boost converter. Based on the nonlinear behavior of power sources and converters, a dynamic model of the system is developed. A nonlinear control technique based on Lyapunov theory is applied to meet the following requirements: (1) accurate DC bus voltage regulation and (2) rapid tracking of battery and UC current to their desired reference values. Both mathematical analysis and simulations are performed to prove the asymptotic convergence of the proposed controller. To verify the performance of the controller, simulations have been done on MATLAB/Simulink, which show that the proposed controller ensures the stability of closed loop system and meet all the control objectives. [ABSTRACT FROM AUTHOR]

Direct current (DC) microgrids are providing a pathway towards zero-carbon based future. This paper proposes a quick reaching law based global terminal sliding mode control (QRL-GTSMC) for a DC microgrid with hybrid power generation including wind, hydrogen and battery. The proposed control scheme reduces the chattering phenomenon and provides fast reaching time. Furthermore, this study discusses two-level control with system level energy management and device level QRL-GTSMC control. The proposed configuration of DC microgrid includes a complete cycle of hydrogen generation, storage and utilization, which increases the system's complexity but improves flexibility. Firstly, the mathematical models of the wind energy system (WES), fuel cell (FC), electrolyzer, hydrogen tank and battery are developed to study their dynamical behavior. Then, the energy management strategy (EMS) and QRL-GTSMC based low-level controllers are designed. The stability of the control scheme is analyzed through Lyapunov stability criteria. After that, the effectiveness of the proposed framework is demonstrated via MATLAB simulations and compared with conventional PID and terminal sliding mode control. Finally, real-time controller hardware-in-the-loop tests based on TMS320F28379D 32-bit microcontrollers are performed. The simulation and experimental results indicate the stable performance of the DC microgrid under varying weather conditions and system uncertainties while ensuring the asymptotical stability of the whole closed-loop system. • Dynamics of hydrogen based DC microgrid are mathematically modeled. • Multiple QRL-GTSMC based nonlinear controllers are designed for DC microgrid. • Simple but comprehensive energy management system is proposed to improve the lifespan of battery and fuel cell. • The theoretical stability of the proposed controllers is examined. • Simulation and experimental analysis are done to test controller's robustness and tracking accuracy. [ABSTRACT FROM AUTHOR]

• Multiple double integral sliding mode controllers (DISMC) for the wind-PV system are presented. • DC bus voltage regulation, MPPT, and transfer of the power to the utility grid are investigated. • The considered system is efficient and allows us to reduce the number of power converters. • Simulations and HIL tests are done to verify the performance of the proposed controller. • The comparative analysis indicates the superiority of the presented DISMC. In this paper, a double integral sliding mode based nonlinear controller (DISMC) is developed for the grid-connected hybrid wind-PV system. The proposed control approach provides better steady state response and robustness as compared to the existing control methods. The topology considered in this study for the wind and PV based hybrid distributed generator system is efficient. Wind and PV generator are connected to the utility grid via boost converter at the machine side followed by inverter at the grid side. Thus, the realized scheme has reduced number of DC-DC conversion stages as compared to the previous schemes. So far, no study investigates the design of nonlinear controller for this scheme. Proposed DISMC offers the maximum power point tracking (MPPT) for both wind and PV generator, DC bus voltage regulation, and smooth transfer of active power to the utility grid. Firstly, the detailed small-signal mathematical models for the proposed hybrid system and DC bus dynamics are developed. After that, three control laws based on DISMC are designed to ensure the stable operation under varying weather conditions and system uncertainties. Then, the stability of the hybrid system is proved using Lyapunov theory. Finally, the performance of the proposed framework has been verified using model-based MATLAB time-domain simulations, and controller hardware-in-the-loop (C-HIL) experiments. The superiority of the proposed control technique was approved by comparing the result with other control methods. [ABSTRACT FROM AUTHOR]

• A nonlinear controller based on integral terminal sliding mode (ITSMC) is proposed for the hybrid AC/DC microgrid. • Performance of the proposed controller is tested during islanding, and grid-connected mode. • Controller hardware-in-the-loop (C-HIL) tests are done to show the effectiveness of the proposed ITSMC. • Results show improved performance of the proposed ITSMC with respect to SMC and CLF. Traditional power generation is in the midst of a major transformation, and renewable based microgrids are playing a key role in this energy structure transition. This paper investigates the design of a centralized nonlinear controller based on the integral terminal and fast integral terminal sliding mode control for hybrid AC/DC microgrid involving renewable distributed generator as a primary source, fuel cell (FC) as a secondary source, and battery-ultracapacitor as hybrid energy storage system (HESS). At first, the detailed mathematical model of the hybrid AC/DC microgrid is established. Then, the controller is designed with the main objective to ensure the constant DC and AC bus voltage during islanding and grid-connected mode. During grid-connected mode, the controller is capable of providing frequency support to the utility grid. After that, the asymptotic stability of the hybrid AC/DC microgrid is proved using Lyapunov stability criteria. Then, the performance and robustness of the proposed control approach are tested by simulating it on MATLAB/Simulink, and the results are compared with sliding mode controller and Lyapunov redesign. Finally, real-time hardware in the loop tests are conducted to validate the effectiveness of the proposed framework. [ABSTRACT FROM AUTHOR]

• Integral backstepping based nonlinear controllers are proposed for the DC microgrid. • Performance of the controllers are observed under different operating cases. • The proposed control framework ensures the stability of the whole DC microgrid. • Real-time hardware-in-the-loop (HIL) tests are done for the validation. Direct current (DC) microgrids are gaining popularity due to their simpler structure and high energy efficiency. This paper investigates the design of an integral backstepping controllers for the DC microgrid involving renewable distributed generators and hybrid energy storage system (HESS). At first, the generic DC microgrid mathematical model is derived. Then, the controllers are designed for PV unit, wind unit, and HESS with the main control objective to regulate the common DC bus voltage. After that, the asymptotic stability of the DC microgrid is ensured through the control Lyapunov function. Finally, the energy management system is adopted to ensure the power balance under variable power generation. The performance of the proposed framework is verified by simulating it on MATLAB/Simulink and comparing the results with adaptive Lyapunov redesign and sliding mode control. Also, the effectiveness of the developed control approach is further validated through real-time controller hardware in the loop experiments. [ABSTRACT FROM AUTHOR]

• Risk analysis in systems with high penetration of renewable energy. • Economic analysis of coupled Transmission and Distribution System. • Applying stochastic coordination, sharing stochastic variables to consider uncertainty of risk and renewable energy. • Polynomial Chaos Expansion for stochastic coordination. • Contingency analysis of transmission and distribution systems and its effect on cost of electricity (Risk-based cost analysis). High penetration of renewable energy has instigated stochastic power injection at interconnection between transmission system (TS) and distribution system (DS). This paper delves into the intricate collaborative risk based stochastic dispatching challenges due to contingencies and the integration of renewable sources in the TS and DS. A framework of risk constrained probabilistic problem (RCPC) is presented, which is divided into Probabilistic coordination (PC) and risk-based stochastic security-constrained unit commitment (RSSCUC). The PC is a stochastic linear problem and RSSCUC is a stochastic mixed integer non-linear problem. Therefore, the probabilistic analytical target cascading along with polynomial chaos expansion (PCE) has been utilized for solving the PC problem for coupled TS and DS. Here, PCE has provided the proposed algorithm with the needed capability to present stochastic shared variables as coefficients for PC. Further, the benders decomposition algorithm has been utilized for solving RSSCUC, by dividing it into master problem and sub problem to generate feasibility cuts. The proposed technique reduces the computational burden on the system, as it requires single stochastic coordination problem for all scenarios as an alternative of each coordination problem for each scenario and polynomial coefficients instead of multiple scenarios for each shared variable between TS and DS. Different case studies have been performed utilizing the 6-bus system and IEEE 118-bus system as TSs, 7-bus, 9-bus, 85-bus and 69-bus systems as DSs. Results depict the efficacy of the proposed method. [ABSTRACT FROM AUTHOR]

The importance of microgrids has been acknowledged with the increasing amount of research in direct current (DC) microgrids. The main reason for this is the straightforward structure and efficient performance. In this research article, double integral sliding mode controllers (DISMCs) have been proposed for energy harvesting and DC microgrid management involving renewable sources and a hybrid energy storage system (HESS). DISMC offers a better dynamic response and reduced amount of chattering than the traditional sliding mode controllers. In the first stage, the state differential model for the grid was derived. Then, the nonlinear control laws were proposed for the PV system and hybrid energy storage system to achieve the main objective of voltage regulation at the DC link. In the later part, the system's asymptotic stability was proven using Lyapunov stability criteria. Finally, an energy management algorithm was provided to ensure the DC microgrid's smooth operation within the safe operating limit. The proposed system's effectiveness was validated by implementing on MATLAB/Simulink software and comparing against sliding mode control and Lyapunov redesign. Moreover, to ensure the proposed controller's practical viability for this scheme, it has been tested on real-time hardware-in-the-loop test bench. [ABSTRACT FROM AUTHOR]

Unlike the plug-in charging system, which has safety concerns such as electric sparks, wireless power transfer (WPT) is less-time consuming, is environmentally friendly and can be used in a wet environment. The inclusion of hybrid energy storage systems (HESSs) in electric vehicles (EVs) has helped to increase their energy density as well as power density. Combined with static wireless power transfer, a WPT–HESS system is proposed in this article. The HESS system includes a battery and supercapacitor (SC) connected to a WPT system through DC–DC converters. To ensure a stable DC bus voltage, an inductor–capacitor–capacitor series (LCC-S) compensation network has been implemented in the WPT system. Utilizing the two-port network theory, the design equations of the LCC-S compensation network are derived in order to realize the maximum efficiency point for the WPT system. To ensure that the WPT system operates at this maximum efficiency point and that the SC is charged to its maximum capacity, an energy management system (EMS) has been devised that generates reference currents for both the SC and battery. An integral terminal sliding mode controller (ITSMC) has been designed to track these reference currents and control the power flow between the energy storage units (ESUs) and WPT system. The stability of the proposed system is validated by Lyapunov theory. The proposed WPT–HESS system is simulated using the MATLAB/Simulink. The robustness of the ITSMC against the widely used proportional–integral–derivative (PID) and sliding mode controller (SMC) is verified under abrupt changes in the associated ESU resistance and reference load current. Finally, the simulations of the WPT–HESS system are validated by controller hardware-in-loop (C-HIL) experiments. [ABSTRACT FROM AUTHOR]

• A scenario based chance constrained programming model including Kirchhoff's law instead of power flow equations is established. The serious voltage and shunt current sources in Kirchhoff's law can be not only simultaneously optimized but also transformed into control devices. • By the equivalent network transformation and basic loop equation, the network reconfiguration can be transformed into optimizing fictitious serious voltage sources in each basic loop instead of binary variables of open/close statue of switches. The solution space is massively reduced and the calculation efficiency is improved. • A cluster of scenarios satisfying the desired confidence level in chance constrained formulations is formed for optimization by k-means algorithm. By optimizing this cluster, the chance constrained formulations can be automatically satisfied. The time consuming optimization of each scenario to find the feasible solution is avoided. • A heuristic solution method which opens loops one by one to deal with radial topology constraint is proposed. This avoids introducing a lot of binary variables for the radial topology constraint as in existing analytic methods. The joint optimization in distribution networks considering the uncertainties in wind power or photovoltaic (PV) outputs is a larger scale stochastic mixed integer nonlinear programming (MINLP) problem. However, how to efficient and accurate solve the problem under uncertainties is still a challenge. To handle the uncertainties, a scenario based chance constrained programming model is established. To improve the accuracy, the network reconfiguration and capacitor control are simultaneously performed by optimizing serious voltage and shunt current sources in the model by using equivalent network transformation. To improve calculation efficiency in dealing with chance constraints, a cluster of scenarios satisfying the confidence level is formed for optimization. To avoid introducing plenty of binary variables for the radial constraint and improving calculation efficiency, a heuristic method opening loops one by one is developed. The numerical simulations on distribution networks show the efficiency and accuracy of the proposed algorithm over the existing methods. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) system generates energy that varies with the variation in environmental conditions such as temperature and solar radiation. To cope up with the ever increasing demand of energy, the PV system must operate at maximum power point (MPP), which changes with load as well as weather conditions. This paper proposes a nonlinear backstepping controller to harvest maximum power from a PV array using DC-DC buck converter. A regression plane is formulated after collecting the data of the PV array from its characteristic curves to provide the reference voltage to track MPP. Asymptotic stability of the system is proved using Lyapunov stability criteria. The simulation results validate the rapid tracking and efficient performance of the controller. For further validation of the results, it also provides a comparison of the proposed controller with conventional perturb and observe (P&O) and fuzzy logic-based controller (FLBC) under abrupt changes in environmental conditions. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive nonlinear control strategy for the energy management of a polymer electrolyte membrane fuel cell and supercapacitor-based hybrid electric vehicle is proposed. The purpose of this work was to satisfy: (i) tight DC bus voltage regulation, (ii) good fuel cell reference current tracking, (iii) better supercapacitor reference current tracking (iv) global asymptotic stability of the closed-loop control system, and (v) better vehicle performance by catering to slowly-varying parameters. We have selected the power stage schematic of a hybrid electric vehicle and utilized adaptive backstepping and adaptive Lyapunov redesign-based nonlinear control methods to formally derive adaptive parametric update laws for all slowly-varying parameters. The performance of the proposed system has been tested under varying load conditions using experimental data from the "Extra Urban Driving Cycle." Mathematical analysis and Matlab/Simulink results show that proposed controllers are globally asymptotically stable and satisfy all the design requirements. The physical effectiveness of proposed system has been verified by comparing simulation results with the real-time controller hardware in the loop experimental results. Results show that proposed system shows satisfactory performance and caters for the time-varying parametric variations and the load requirements. [ABSTRACT FROM AUTHOR]

Compared to the plug-in charging system, Wireless power transfer (WPT) is simpler, reliable, and user-friendly. Resonant inductive coupling based WPT is the technology that promises to replace the plug-in charging system. It is desired that the WPT system should provide regulated current and power with high efficiency. Due to the instability in the connected load, the system output current, power, and efficiency vary. To solve this issue, a buck converter is implemented on the secondary side of the WPT system, which adjusts its internal resistance by altering its duty cycle. To control the duty cycle of the buck converter, a discrete fast terminal sliding mode controller is proposed to regulate the system output current and power with optimal efficiency. The proposed WPT system uses the LCC-S compensation topology to ensure a constant output voltage at the input of the buck converter. The LCC-S topology is analyzed using the two-port network theory, and governing equations are derived to achieve the maximum efficiency point. Based on the analysis, the proposed controller is used to track the maximum efficiency point by tracking an optimal power point. An ultra-capacitor is connected as the system load, and based on its charging characteristics, an optimal charging strategy is devised. The performance of the proposed system is tested under the MATLAB/Simulink platform. Comparison with the conventionally used PID and sliding mode controller under sudden variations in the connected load is presented and discussed. An experimental prototype is built to validate the effectiveness of the proposed controller. [ABSTRACT FROM AUTHOR]