Multi-port DC Research Articles

A hybrid multi-port HVDC circuit breaker that improves interruption and reset time through shared energy dissipation and fault current regeneration

This paper proposes a Hybrid Multi-Port DC Circuit Breaker (HMPDCCB) design that addresses the limitations of existing hybrid DC circuit breakers (HDCCBs), such as high cost, complexity, and slow response to high fault current and voltage demands. The HMPDCCB is based on a common breaker, energy dissipation, and regeneration branch for all connected HVDC lines, reducing interruption time to 1.8 milliseconds. It effectively manages fault energy through Insulated Gate Bipolar Transistors (IGBTs) of the main breaker branch with parallel surge arrester, reducing energy losses and enhancing power system efficiency. The HMPDCCB provides selective protection for all connected DC lines at a lower investment cost and incorporates current-limiting inductors (CLIs) to slow the rise of fault currents. The proposed HMPDCCB has been rigorously modelled and simulated using MATLAB Simulink®/Simpowersystems, and the simulations show that it achieves a fault current interruption time of 1.8 milliseconds and a reset time of fewer than 3 milliseconds, outperforming existing models.

Single‐stage single‐phase multiport DC–AC inverter suitable for standalone applications due to its notable performance in different operation modes

AbstractA new multiport DC–AC converter is proposed for standalone and off‐grid tied applications. The configuration converts power from DC to AC form in a single stage with suitable voltage gain. To increase the certainty of supporting power, the converter is designed to operate in four modes, including battery‐alone mode. The other advantage of the presented work is supplying the output power during unbalanced voltage conditions of the input ports. The advanced features of the converter for being used in standalone applications are related to the suitable placement and structure of the bidirectional port. In addition, the configuration is designed in a way to contain appropriate structural properties such as the existence of a common ground between the DC section and inverter, continuity of input currents, configured by an acceptable number of components, and low‐voltage stress on the DC–DC section's switches. Furthermore, it has an impedance network to protect the inverter's switches in a shoot‐through state. To confirm the converter advantages from the mentioned points of view, it has been compared with similar configurations. A prototype rated at 110 V is prepared to demonstrate the advantages of the converter performance per different conditions. The results of the steady‐state and transient experiments validate the suitability of the presented converter.

Solar energy harvesting under partial shading conditions through a reconfiguration strategy using a multi-port DC–DC converter

Solar energy harvesting under partial shading conditions through a reconfiguration strategy using a multi-port DC–DC converter

Multi-port DC transformer applied to large-scale DC collection systems

Abstract This paper proposes a multi-port DC transformer for boosting and flexible interconnection in large-scale DC collection systems. It can transmit power and adjust port current, while also having a relatively simple control strategy. The engineering practicality of the proposed DC transformer can be well verified through the simulation of a 4 GW DC collection system. In this application scenario, the proposed DC transformer can operate stably and safely under both dynamic and steady-state conditions.

Common-Mode Voltage Reduction Method-Based Flexible Power Control for Multiport DC–AC Converter in PV–Battery Hybrid System

Common-Mode Voltage Reduction Method-Based Flexible Power Control for Multiport DC–AC Converter in PV–Battery Hybrid System

A novel multi-port high-gain bidirectional DC–DC converter for energy storage system integration with DC microgrids

Bidirectional converters have often been used in numerous applications like DC microgrids, renewable energy, hybrid energy storage systems, electric vehicles, etc. The paper proposes a novel multi-port high-gain (NMPHG) bidirectional DC–DC converter that supports DC microgrid (DC-MG) applications. The main contributions of the proposed converter are high step-up/step-down conversion gain, multiple input ports, lower switch voltage stress, and lower component count owing to the single converter with multiple input ports for DC microgrid applications. The detailed operational principle, analysis, and design considerations of proposed NMPHG bidirectional DC–DC converters are discussed. Furthermore, the loss analysis, detailed comparison with similar works, and efficiency analysis with non-modalities during forward power flow (LV to HV) and reverse power flow (HV to LV) modes are presented. The efficiency of the proposed converter is found to be 93.8% in forward power flow and 92.9% in reverse power flow modes at rated power. Finally, a hardware prototype of the proposed NMPHG bidirectional DC–DC converters is implemented with 100 W in FPF mode and 200 W in RPF mode with a TMS320F28335 processor and validated with theoretical counterparts.

An Improved AC-Link Voltage Matching Control for the Multiport Modular Multilevel DC Transformer in MVDC Applications

In this paper, an improved AC-link voltage matching control (IVM) strategy is proposed for the multiport modular multilevel DC transformer (M3DCT), which comprises a single-phase modular multilevel converter (MMC) and a series of cascaded H-bridge units. The objective of the proposed IVM strategy is to address the AC-link voltage mismatch phenomenon. Distinct from existing control methods, such as various phase-shifting control methods and the conventional AC-link voltage matching control strategy, the proposed IVM strategy orchestrates the operation of the M3DCT in an innovative fashion. It allows the sum of inserted submodule (SM) numbers in the upper and lower arms to be flexible, no longer confined to a specific SM number per arm. Consequently, the AC-link voltage of the M3DCT is maintained proximate to the matched operating condition, regardless of the degree of mismatch in the DC side voltage of the M3DCT. This enables the enhancement of the M3DCT’s overall operational performance, particularly under conditions of light loads within medium-voltage DC (MVDC) distribution systems. The correctness and effectiveness of the proposed control strategy and the corresponding analysis are substantiated through simulation results.

A multi-port DC–DC–AC system based on CLLC resonant converter and FSBB converter

A multi-port DC–DC–AC system based on CLLC resonant converter and FSBB converter

A Multi-Functional Multi-Port Hybrid DC Circuit Breaker for Flexible DC Distribution Networks

A Multi-Functional Multi-Port Hybrid DC Circuit Breaker for Flexible DC Distribution Networks

New multi-port hybrid DC circuit breaker for DC power grids

New multi-port hybrid DC circuit breaker for DC power grids

The Optimization of PEM Fuel-Cell Operating Parameters with the Design of a Multiport High-Gain DC–DC Converter for Hybrid Electric Vehicle Application

The fossil fuel crisis is a major concern across the globe, and fossil fuels are being exhausted day by day. It is essential to promptly change from fossil fuels to renewable energy resources for transportation applications as they make a major contribution to fossil fuel consumption. Among the available energy resources, a fuel cell is the most affordable for transportation applications because of such advantages as moderate operating temperature, high energy density, and scalable size. It is a challenging task to optimize PEMFC operating parameters for the enhancement of performance. This paper provides a detailed study on the optimization of PEMFC operating parameters using a multilayer feed-forward neural network, a genetic algorithm, and the design of a multiport high-gain DC–DC converter for hybrid electric vehicle application, which is capable of handling both a 6 kW PEMFC and an 80 AH 12 V heavy-duty battery. To trace the maximum power from the PEMFC, the most recent SFO-based MPPT control technique is implemented in this research work. Initially, a multilayer feed-forward neural network is trained using a back-propagation algorithm with experimental data. Then, the optimization phase is separately carried out in a neural-power software environment using a genetic algorithm (GA). The simulation study was carried out using the MATLAB/R2022a platform to verify the converter performance along with the SFO-based MPPT controller. To validate the real-time test bench results, a 0.2 kW prototype model was constructed in the laboratory, and the results were verified.

SIMULATION MODELING OF MULTI-PORT DC-DC CONVERTER IN MPPT SOLAR BATTERY CONTROLLERS UNDER NEURAL NETWORK CONTROL

Photovoltaic generation system - energy system, designed to convert useful solar energy through photovoltaic systems. It can consist of several components, including a solar array, DC/DC and DC/AC semiconductor converter, battery, filter or transformer, control system (CS). Depending on the application, photovoltaic systems can be operated as part of a self-contained power plant or operate on a network. Thus, it is possible to distinguish several basic configurations of photovoltaic generation systems. The standalone generation system is the most common configuration of photovoltaic generation systems, which contains rechargeable batteries (AB). This system is completely independent of the centralized power supply networks and is suitable for comfortable energy supply to consumers. The use of AB makes it possible to increase the reliability of the photovoltaic system and to extend the possibilities of using e.g. battery power is used during insufficient light or when the load exceeds the generation of solar cells. The scope of such configurations are lighting systems of residential and non-residential objects, power supply of houses and buildings, security systems and emergency power supply, power supply of remote residential and non-residential objects, Power supply to spacecraft, etc. Autonomous generation systems typically contain two transducers. The DC/DC converter acts as a battery charge controller. The control system for such a transducer may include the function of tracking the maximum power point for the maximum use of solar energy. The excess energy will be stored in AB. The DC/AC converter converts the DC current energy into the AC energy of the required frequency and voltage. The advantage of such a system is the possibility of using solar energy, both during the day and at night, due to the power of AB and the possibility of using the system at remote sites where there is no grid power supply. The disadvantage of such a system is the loss of double conversion of solar energy and the high cost of batteries. Artificial Neural Network (ANN) provides an alternative way to solve complex problems. A neural network, with the right structure, can compute the values of any continuous function with some predetermined accuracy. The neural network requires no knowledge of the internal parameters of the solar module, learns quickly, has the ability to optimize and approximate. Therefore, the use of INS to track the maximum power point is relevant and of practical and scientific importance. Keywords: multi-port DC converter, artificial neural network (ANN), rechargeable batteries (AB), pulse width modulation (PWM), solar panels (SP), MOSFET power keys

Novel Centralized Drive Circuit for Fast Vacuum Switches in Multiport DC Breaker

Novel Centralized Drive Circuit for Fast Vacuum Switches in Multiport DC Breaker

Topology and Control of Multiport DC Circuit Breaker Integrating Current-limiting and Fast Fault Clearing Capabilities

Topology and Control of Multiport DC Circuit Breaker Integrating Current-limiting and Fast Fault Clearing Capabilities

Modular cascaded multi-port DC circuit breaker with fault current-limiting capability

Modular cascaded multi-port DC circuit breaker with fault current-limiting capability

Robust energy storage system for stable in wind and solar

Energy storage systems (ESS) have become a conspicuous research hotspot since they store power and supply it during peak hours. Existing storage systems must be replaced by advanced energy storage with improved performance, energy management, and a control interface due to issues with size, dependability, and charging/discharging. The suggested robust energy retention system uses a battery and a super-capacitor to generate power from wind and solar energy. A Multiport DC converter with a buck-boost capacitor is used to properly discharge the stored energy to DC loads via a DC bus. The inverter is then delivered to a Power Flow Controller (PFC) and a Voltage Source Inverter (VSI). The Gravitational Search Algorithm (GSA) method optimizes the power controller settings based on the fluctuation of the system's active and reactive power. The optimization method ensures improved power flow while dealing with the least amount of power variance in imbalanced load situations. Based on the power variation, the proposed method generates appropriate control signals for the inverter system. The covers convert the inverter and reduce harmonics with a controller. Furthermore, the inverter AC supplied to the AC bus is converted into reactive power by an inductive load, and unwanted signals and harmonics are extracted using a Cascaded C-type filter. As a result, the described method has preserved total harmonic distortion, electrical efficiency, and finer transient stability.

Multi-Port Hybrid DC Circuit Breaker Based on Bridge Commutation Branch

Flexible DC grids have become an important means to support large-scale new energy integration utilization due to their advantages of flexible power control and high efficiency. Flexible DC grids generally consist of multiple converter stations and DC lines. Therefore, there are multiple line intersection points, and DC circuit breakers (DCCBs) need to be installed at the intersection to isolate faults. Multi-port hybrid DCCBs (MPHCBs) based on topology optimization can greatly reduce the cost by replacing multiple two-port DCCBs with one multi-port DCCB at the intersection. However, currently researched multi-port DCCBs still have a high cost and large volume while lacking engineering verification. This paper proposes a hybrid multi-port DCCB based on a bridge commutation branch that greatly reduces the number of power electronic devices used and the cost and volume of the DCCB. First, the topology and control method of the proposed MPHCB are studied, and its cost and reliability are analyzed. Then, the breaking test of the proposed MPHCB based on the bridge commutation branch is carried out at a 15 kV voltage level. The results show that the proposed MPHCB can interrupt a 15 kA current in 3 ms, which verifies the feasibility of the scheme.

A multiport hybrid DC circuit breaker with high economic efficiency and adaptive reclosing capability

In a high voltage direct current (HVDC) grid, hybrid DC circuit breakers (HCBs) are one of the effective solutions to interrupt fault currents. The conventional two-port HCB features high economic costs since the expensive insulated gate bipolar transistors (IGBTs) are needed. Each line in the multiterminal HVDC grid must be equipped with the HCB, which is extremely costly to implement. In addition, the likelihood of temporary faults is considerably raised by the fact that the HVDC grid transfers power across overhead lines (OHLs). By reclosing operations after temporary faults, the HVDC grid can resume normal operation. However, it is vital to discern between temporary faults and permanent faults before reclosing operation to prevent secondary shocks to the HVDC grid caused by blindly reclosing on permanent faults. For the problems of high cost and blind reclosing of HCBs, this article proposes a multiport HCB (MHCB) with high economy and adaptive reclosing capability. All ports of the MHCB share a single main breaker (MB) for fault isolation. The MHCB utilizes the capacitor voltage to lower the operating voltage of the metal oxide varistor (MOV), which reduces the number of IGBTs connected together at both ends of the MOV. With the above design, the expense of the MHCB is significantly decreased. Additionally, the MHCB achieves adaptive reclosing by using the difference of current amplitudes in the capacitor branch under permanent and temporary faults.

An Isolated Multiport DC–DC Converter for Integrated Electric Vehicle On-Board Charger

An Isolated Multiport DC–DC Converter for Integrated Electric Vehicle On-Board Charger

A Multi-Port DC Power Flow Controller Integrated With MMC Stations for Offshore Meshed Multi-Terminal HVDC Grids

Multi-terminal dc (MTDC) systems have the potential to facilitate the integration of offshore wind farms. A dc power flow controller (DPFC) is necessary for meshed multi-terminal high voltage dc (HVDC) grids to regulate the power flow in dc lines. However, DPFCs based on modular multilevel converters (MMCs) require two dc-ac conversion stages and an extra ac transformer, which increases the cost and loss for offshore platforms. This paper proposes a multi-port DPFC that is integrated internally into the offshore MMC station, eliminating the need for an extra transformer and reducing dc voltage ripple. Additionally, the full bridge submodules (FBSMs) in the DPFC can further reduce the number of FBSMs required in the MMC station for dc fault blocking. The proposed DPFC is composed only of cascaded FBSMs connected to the arms of the offshore MMC station, which can exchange power directly with the MMC valve to achieve power balance. By using the MMC station, the proposed DPFC requires a small kVA rating, approximately 1%-5% of the total system power rating. The performance of the proposed DPFC is validated through simulation of a hybrid system of the IEEE 39 bus and the Cigre HVDC benchmark, and also through down-scale experimental testing.