The concept of partial power processing was developed to reduce the power processes by converter components to increase efficiency and power density. This paper investigates the behavior of partial power converter (PPC) applied to photovoltaic (PV) systems. This paper uses a series PPC to integrate a PV string into a DC bus. Extracting maximum power from PV string is problematic for PPC at near-zero partiality. At this point, the converter does not change its quadrant if needed, and the controller saturates. This leads to a loss of the maximum power point. This paper introduces a seamless maximum power point tracking method with enhanced performance near zero partiality. The proposed concept is verified through numerical simulations in PSIM.
The paper presents a method for derivation of the minimum split DC link capacitance in three-phase three-level DC-AC converters operating with unity power factor with neither active balancing circuits nor AC zero sequence injection. It is shown that due to the fact that partial DC link voltages and AC-side phase voltages obtain extremum values at different instants, it is possible to reduce the minimum value of the former below maximum value of the latter while still ensuring correct operation of the power stage. Minimum attainable split DC link capacitance values are therefore obtained according to boundary case of tangency between the above-mentioned voltages. Analytical derivations are accurately verified by simulations and experiments, demonstrating close agreement.
Digital twins (DTs) are playing a vital role nowadays in the EV industry. Since their inception, DTs have contributed significantly to the research development process. PMSMs are, are widely used in electric vehicles (EVs) due to their simple structure, good heat radiation capability, and high efficiency. In this paper, the performance of an EV-PMSM control strategy is evaluated based on DT concept. General principles of DT technology were discussed. The performance control model of PMSM was derived. Field-oriented control (FOC) and direct torque control (DTC) strategies for EVPMSM were discussed and compared. The PMSM DT architecture including physical, virtual, and service unit (data exchange) was proposed. EV-PMSM DT primarily functioned to evaluate the motor control algorithm. The motor’s actual speed was compared to the estimated one by its DT. The obtained results showed the effectiveness of the proposed DT to estimate the motor speed which would be used to develop a speed estimator to optimize the motor control strategy.
With technological progress and the industrial automation revolution, electric self-driving vehicles (ESDV) have become the focus of global attention by different automotive manufacturers. The primary stage in the vehicle development process is modeling and simulations. Risk reduction, waste minimization, efficiency improvement, and energy combustion savers are the main pros of system simulation. This paper presents a detailed simulation dynamic model of (ISEAUTO) self-driving vehicles. An overview of the latest trends concerning ESDV dynamics is discussed. The detailed model framework of the ESDV is proposed. The simulation model of each vehicle component is built using MATLAB/Simulink. The obtained simulation characteristics are compared to the actual vehicle to validate the proposed experimental analysis’s target effectively.
With the benefit of high power density and bidirectional multi-input multi-output (MIMO) power transfer capability, the multiport active bridge (MAB) topology has been widely used in the electric transportation onboard propulsion and charging systems. However, the nonlinear power transfer behavior brings challenge to its control system design. As the dynamic performance of the traditional proportional-integral (PI) controller is characterized by a relatively slow response and large overshoot. To address this issue, decoupling control strategies have been proposed to enhance the transient response and control flexibility of the system. This paper discussed and compared several nonlinear decoupling control methodologies including the small signal state-space linearization based and optimization algorithm based decoupling control. Simulation verifications are performed to conclude the suitable applications.
Given the growing presence of microgrids, it is necessary to investigate how communication protocols impact their behavior. The study of DC microgrid topologies is of great importance due to their fast proliferation and the fact that they allow for quick and easy integration of energy generation and storage systems since both are also of DC nature. This paper presents a comprehensive study of how the communications protocols and control strategies affect the behavior of a DC microgrid. There is no standard communication protocol in DC microgrids; therefore, it is relevant to perform experimental tests of the control schemes implemented over various communication protocols to study intrinsic communications problems such as delays and package losses. This paper reviews the communication protocols used to implement microgrid control strategies with a particular focus on their experimental validation. Finally, the experimental results are presented by employing a hardware-in-theloop system to model a DC microgrid and with a communications board to implement different control topologies
In recent years, many research projects aimed at improving buildings’ energy efficiency through active and passive solutions. However, few of these projects are addressing the presence of critical loads. The IMPROVEMENT project, "Integration of combined cooling, heating, and electricity microgrids in public buildings with zero energy consumption under high energy quality and service continuity requirements", aims at this double scope of action, developing innovative technologies that allow public buildings to move towards a sustainable energy model, while simultaneously increasing the security of energy supply for critical services. With several months to go until the end of the project, the document presents the latest developments and lessons learned to date in relation to the power management system, and the IoT-enabled power quality data analytics platform deployed.
In modern DC distribution networks both consumer and prosumer devices are interfaced to the grid via power converters equipped with suitable filtering circuitry to mitigate conducted electromagnetic interference (EMI), also referred to as conducted emissions (CE). However, the presence of asymmetries in the converter, such as the deviation of the component parameters from the designed ones and possible device failure, can significantly alter the input current and voltage waveforms while the device still works satisfactorily. This inevitably leads to an increase in the harmonic pollution in the power grid, being the EMI filters designed for acting on different waveforms. This paper investigates the effect that non-idealities of power switches have on the input current of an H-bridge inverter.
The energy transition requires electrical alternatives for domestic heating. Heat pumps are the most common alternatives to gas boilers. However, heat pumps consume a significant amount of electrical power. We simulated an 18-node low voltage network with five buildings with six apartments each to evaluate the effect of deploying heat pumps as part of multi-carrier energy systems at the residential level. We also combined heat pumps with solar collectors and thermal energy storage to quantity whether a more complex system benefits the low-voltage network. Replacing the gas boilers for heat pumps in the majority of the buildings resulted in voltage drops below the limit of the standard EN50160. The voltage drops were significantly improved when we included solar collectors and thermal energy storage in the domestic heating system.
Modular multi-level converter (MMC) is a popular multi-level converter configuration due to its various features such as ease of scalability, modularity, and low voltage and current rating demand for the power switches. This paper presents the development and implementation of hardware prototype of MMC as a grid forming inverter. An MMC prototype is developed having three sub-modules in an arm, which can be configured as either half bridge-based sub-module or full bridge-based sub-module. Design of various circuits and sizing of various components are carried out for the MMC setup. All the hardware related design and control technique are discussed. Lastly, hardware results for operation of MMC as grid forming inverter are presented.
Fault location in power transmission systems must be fast and effective, in order to provide a quick response, thereby reducing the interruption time. Currently, methods of fault location in power transmission lines are classified in four categories, namely: impedance-based methods, travelling waves methods, high frequencies methods and artificial intelligence methods. Among them, one of the most interesting is the traveling waves based, however, one aspect that can affect this method is the sampling frequency. In this way, this paper will present a study regarding the influence of the sampling frequency for traveling waves based fault detection method. Some tests and results will be presented in order to show the impact of the different sampling frequencies on the performance of the fault detection method.
This paper presents issues related to implementing energy storage in a low-voltage distribution grid with many renewable sources. The purpose of the storage installation is to balance and stabilise the mains voltage. Thanks to this, outages of prosumer photovoltaic installations are limited and energy from RES can be used more effectively without expanding the distribution infrastructure. The article presents the concept and operation modes of the energy storage system illustrated with the course of actual research registered during the pilot project implemented in the Ochotnica Dolna Commune in cooperation with the AGH University of Science and Technology and Tauron Dystrybucja.
This paper presents an investigation on a non-isolated, three-level DC/DC converter; more specifically, on the possible combinations of inductor configurations and modulation techniques directly affecting the performance of the converter. The many state-of-the-art and conventional solutions are compared theoretically, as well as based on experimental considerations founded on a medium voltage SiC-based DC/DC converter to be applied as an energy storage interfacing system in a fast charging station. The study focuses on the effects of the configurations on the output ripples of the converter, which is crucial for battery-oriented systems. The tests were performed at 1 kV and up to nearly 10 kW of power, successfully validating the use of each configuration. It is shown that for a system to operate in a wide output range, the current ripple criterion is not enough for choosing the optimal configuration, and other factors, e.g., efficiency, must be considered.
The growing popularity of electric vehicles has led to more demanding requirements for on-board chargers (OBCs) in terms of size and efficiency as well as functionalities, e.g. world-wide compatibility and bi-directionality. The state-of-the-art solution of OBCs is a phase-modular design which comprises a large number of components and is thus inherently limited in the achievable power density. The next generation of OBCs are therefore true three-phase topologies like the B6/B8 topology featuring 1200V-rated SiC MOSFETs which can be merged into a unified topology for single- and three-phase compatibility. Further power density improvements demand a transition towards multi-level topologies with 600V-rated GaN HEMTs which allow to break the performance barriers of classic 2-level topologies. This is derived for the PFC and the DC/DC stages based on fundamental scaling laws as well as Pareto optimizations of the employed passive components. As an outlook for further power density increases, on the one hand the concept of the non-isolated OBC, and, on the other hand, the single-stage power conversion enabled by monolithic bi-directional GaN HEMTs are described.
The new Italian standard CEI 0-21 allows the choice about single-phase or three-phase connection to the Distribution System Operator (DSO). This applies to Photovoltaic Systems (PVSs) with power up 10 kW. Single-phase connection to the grid is adopted for power below 6kW. Differently, both single-phase connection and three-phase connection are possible in the range [6–10] kW. Single-phase transformer-less DC/AC converters can exhibit some issues about the compliance with safety requirements. As the transformer-less inverters market is becoming more competitive, the aim of this paper is to benchmark some single-phase transformer-less DC/AC converters providing a fair comparison. The performances are evaluated considering leakage current, reactive power handling capability, power quality, filter and power converter rating.
During the last few years, the idea of a single battery system for DC load supply has been expanded to provide the possibility to parallel work of two different energy storage types: one with high power density e.g., supercapacitor (SC), and a second with high energy density – usually electrochemical Lead Acid or Li-Ion batteries. A system composed of both kinds of energy storage is known as a hybrid energy storage system (HESS). It ensures high power capacity during load changes, which helps decrease the DC bus voltage error in transient. Simultaneously the HESS delivers the energy to the load from the source characterized by high energy density, which provides the power balance for a long time in a steady state. The advanced hybrid energy storage system and different characteristics of utilized energy sources required a novel control method, which improves energy management inside the HESS. It necessitates independent energy management for high-power density and high-energy density storage. Due to the utilization of energy collected in the SC under transients, the control algorithm of the HESS should provide its stored energy in order to keep the voltage of the DC bus constant, which results in the need to recharge the SC after load change. In the paper, a novel control method has been described, which provides the constant DC bus voltage as well as the constant voltage of the SC in the steady state of HESS. As a result, the fully charged SC can be utilized in each dynamic state as well as during the short battery overload, when the current of the battery is limited.
The use of renewable energy is increasing ever so highly during this modern age of technology. The use of wind, solar and hydro energy is rising rapidly in the world due to the less emissions of harmful gases in the atmosphere. Since the energy produced from these sources like wind and solar energy is increasing a lot, the use of grid connected inverters is also expanding. Deep analysis of these inverters’ operation is important when working in non-ideal situations. The main aim of this paper is to analyze the operation of a three-phase photovoltaic power plant (rated at 250 kW) supplying power to both three-phase and single-phase loads. The analysis covers both, connected and disconnected modes and also includes the performance of a basic islanding detection method considering voltage and frequency deviation of the phase locked loop (PLL) at the Point of Common Coupling (PCC) and the effect on the whole system considering unbalanced situations with different values of irradiances is observed. The novelty of this paper is to identify a case in which the islanding detection fails due to the connection of a single-phase load in the point of low voltage.
Energy Communities are a key stakeholder of modern electrical power grids. Operating an energy community is a challenging topic due to the involved uncertainties, complexities and often conflicting objectives. The aim of this paper is to present a group of metrics that is used to evaluate the capacity of an Energy Community to mantain the wellbeing of each community member when a grid fault occurs. One energy community will be modulated considering as consumption sources noncontrollable and controllable devices in each house and as power supply sources PV systems installed in community’s houses as well as power from main grid or storage system. Genetic algorithms will be used with different cost functions to evaluate different scenarios.
Multiport converters are used in various applications, where it is needed to interface multiple sources and multiple loads. As an example, multiport converters are used in renewable energy applications, distribution grids, electric vehicles, etc. Another field of application of multiport converters can be power supply units for medical equipment. To increase the reliability of medical equipment, it is beneficial to use batteries as a backup supply, in case of failures in the main power source. Also, modern medical equipment can have several functions, and different loads may require different characteristics of input voltages and currents. As an example of such modern medical equipment there is a surgical lighting system with adjustable positioning of reflector during the operation of the system. Such a luminaire requires different voltage levels for different system parts (LED drivers, control unit, sensors, etc.). Considering the necessity of adding backup power supply, the most suitable solution is the application of multiport converter. This paper deals with the initial evaluation of partially isolated multiport converter with the help of Matlab-Simulink model.
The study focuses on a serial manipulator control for motion simulation. Two motion cueing algorithms were compared for the case of luge sports simulation - the Classic Washout Filter (CWF) and its advanced version utilizing cylindrical coordinates (CYL). The tuning process of both algorithms is described considering the high dynamics of luge sport as a main challenge. Simulation has been tested on a group of people and simulation quality has been assessed. The luge sportsmen rated the fidelity of the simulation as satisfactory, indicating that the CYL algorithm has more dynamics. A few possible enhancements to improve simulation quality have been suggested.
