Fulwani, Deepak M

DC Microgrids are vital in integrating renewable energy sources and supplying power to different critical and non-critical loads. However, this system's fundamental challenges are maintaining the voltage at the DC bus and equal current sharing among the parallel-connected converters even when the sources and loads are dynamic. This paper presents a novel non-linear discontinuous sliding mode controller for two Solar Photovoltaic, and a Battery Energy Storage System (BESS) based DC Microgrid. The proposed control technique precisely regulates the DC bus voltage and maintains equal load current sharing. Also, State of Charge (SoC) and Voltage-based charging and the discharging algorithm are implemented for the battery-interfaced bidirectional converter. In addition, the load shedding scheme for the non-critical loads is also implemented. The MATLAB simulation results ensure the DC Microgrid's desired operation under different operating conditions.

This paper proposes a novel notion of Adaptive Sliding mode based loss free resistor (ASLFR), to achieve the dual purpose of power factor correction and voltage regulation. The scheme serves itself as an efficient solution for single-stage PFC circuits applications. The work also provides a qualitative analysis to establish the expediency of the proposed ASLFR over the existing SLFR technique. A boost topology is chosen for implementation, to showcase the effectiveness of the scheme. Relevant results have been demonstrated to support the theoretical claims.

An academic institute is a system of systems that consist of departments, administration, and external resources as subsystems. These subsystems can be further divided into smaller active subsystems of students, faculties, external industries, placement unit. For active and dynamic subsystems, predicting its behavior for any action is undeterministic. The complex and uncertain operating environment of an institute makes the decision making process difficult using the regular qualitative analysis based approach. This paper presents a digital twin based approach to enable data-driven quantitative analysis to the decision-making process that can provide feedback to the academic institute on various decision options before taking an actual decision. Our approach has used an artificial intelligence concept called Bayesian Network to develop the digital twin of the department to help department-level stakeholders to take qualitative, data-driven, and simulated verified results that help in taking departmental-level decisions. The Digital twin takes input from the department data, and current situational data, that is fed to the department's Bayesian Network and thus provides feedback to the department regarding various decision options available.

The distributed control of dc microgrid requires communication of the voltage or per-unit current data between the neighboring nodes. This data is processed by the secondary controller to generate a reference for the primary controller. Any uncertainty in the communicated data leads to the oscillations in the dc bus voltage, disproportionate load sharing, or instability due to erroneous references generated. In this work, an ISMC based secondary controller is proposed, which tunes the voltage reference within the regulation range and also mitigates the bounded uncertainties in the communicated microgrid load data. The ISMC has the advantage of elimination of the reaching phase, as the desired node trajectories start from sliding manifold. This makes the secondary control robust throughout the operating range and facilitates proportional load sharing in uncertain operating conditions. The proposed secondary control compares the actual node parameters with the desired global reference values and generates the control signal, which is added with the primary controller's control signals. The proposed control methodology requires only local parameters for formulation. This eases the control design process. Further, a sliding mode control based primary control (SMPC) is proposed to regulate the voltage of a node and facilitate plug and play among the microgrid interfacing converters. The proposed robust SMPC has excellent control during load transients and plug-in and out of nodes from the dc bus. The proposed control is verified using simulations and experiments on a three-node dc microgrid.

A controllable networked system is steered from an initial state to the desired state with the help of a set of driver nodes. The set of driver nodes used to control a networked system may not be unique. There exist multiple set of driver nodes which may be utilized to control the networked system. This is imperative to characterize these sets of driver nodes for identification of an optimal set of driver nodes. This paper presents mathematical formulation and two algorithms using the Region of Attraction (ROA) to identify an optimal set of driver nodes. Optimal set of driver nodes is identified to maximize the stability region. For any practical networked systems, driver node has limited actuating capacity, this paper consider this limitation a priori. The proposed mathematical formulation and algorithms are verified with the help of numerical examples using the MATLAB simulation. The proposed algorithms have been validated by applying on a robotic network.

Single-phase inverter suffers an unwanted second-order ripple at DC input of it. A substantial amount of this ripple may propagate through the system components and inject into the DC source. This causes several problems; related to system efficiency, life, cost, size, reliability and stability. This paper proposes an adaptive non-linear sliding mode controller for quasi-switched boost inverter used mainly in microinverter applications. The proposed controller shapes the output-impedance of the boost circuit of quasi-switched boost inverter such that the propagation of the ripple to DC source is resisted. The proposed control technique is verified using Matlab-Simulink.

This article presents emulation of a programmable power electronic, constant power load (CPL) using a dc/dc step-up (boost) converter. The converter is controlled by a robust sliding mode controller (SMC). A novel switching surface is proposed to ensure a required power sunk by the converter. The proposed dc CPL is simple in design, has fast dynamic response and high accuracy, and offers an inexpensive alternative to study converters for cascaded dc distribution power system applications. Furthermore, the proposed CPL is sufficiently robust against the input voltage variations. A laboratory prototype of the proposed dc CPL has been developed and validated with SMC realised through OPAL-RT platform. The capability of the proposed dc CPL is confirmed via experimentations in varied scenarios.

The paper proposes a theory and an algorithm to characterize driver node (control node) of a complex network. The proposed algorithm identifies an appropriate driver node when multiple options are available to select a driver node. The method is based on concept of maximization of stability regions. A realistic situation where driver node has limited actuating capability is considered. The proposed control law considers actuator saturation a priori and also ensures a specified convergence rate. Formation control in robotic network and numeric examples are used to verify the theoretical developments.

In this paper, we consider the event triggered control of the singularly perturbed linear system, where the communication between sensor and the controller/actuator is through a digital communication network and the transmission is based on some state dependent criterion. The models of slow and fast subsystems of the plant are added at the controller and are used for the estimation of states between the transmission times. Whenever the difference between estimated and actual states exceeds a certain threshold, controller is updated with the actual states of the plant provided by the sensor. This effectively reduces the communication frequency. The stability properties of overall closed loop system is studied and it is found that for sufficiently small value of singular perturbation parameter, system attains practical stability and by adequately selecting trigger function parameters, asymptotic stability is also achieved. A numerical example is shown to illustrate the results of the paper.

In more electric aircraft (MEA), three phase power factor correction (PFC) rectifiers of several kilowatts are required. In this paper, a three phase buck-boost derived PFC converter with inductors connected in delta configuration for aircraft application is presented. The proposed converter is operated in discontinuous conduction mode (DCM) to achieve PFC at ac input. This avoids the inner current control loop which further eliminates the current sensors. It requires only one output voltage sensor unlike five sensors in conventional PFC converter and uses a simple voltage control loop to regulate the output voltage. This makes the system cost effective, more reliable and robust. The steady state operation, design calculations and simulation results are presented. The experimental results from a 2kW laboratory prototype are also presented to confirm the operation of the proposed converter.