Energy Router Research Articles

A new DC bus voltage control strategy for energy routers based on distributed coordination optimization

Abstract The types of power ports of energy routers at the side of the distribution network platform are complex and have different characteristics, which makes the operation conditions of energy routers complex and changeable. Although many pieces of literature have proposed more relevant control strategies to effectively realize the efficient and stable operation of energy routers under the two basic working conditions of grid-connected and isolated islands. However, when considering various complex operating conditions such as start-up, overload/overcharge, sudden failure of distribution network, grid-connected, and inter-island switching, the reliable operation of the existing energy routers is still faced with great challenges. In this paper, a DC bus voltage control strategy based on distributed coordination optimization is proposed for typical operating conditions of energy routers. Simulation results show that this strategy can effectively achieve the DC bus voltage control performance of energy routers under various burst operating conditions and strengthen the robustness of output voltage of energy routers under isolated islands.

Voltage control strategy of output bus of grid-connected port of energy router based on energy feedback

Abstract The remaining power conversion ports are equivalent to constant power loads for the grid-connected port of the voltage source. The negative impedance characteristics of the constant power loads will worsen the voltage source characteristics of the grid-connected port and even cause system instability. According to the influence mechanism of constant power load on the DC bus voltage control performance during grid-connection, a new voltage control strategy based on energy feedback is proposed in this paper. The simulation results show that the proposed control strategy can more effectively reduce the negative impedance characteristics of the energy router’s constant power load and improve the bus voltage’s control performance compared with the existing control strategies.

A Bridge-Arm Multiplexed Bidirectional Isolated DC/DC Converter for Energy Routers

A Bridge-Arm Multiplexed Bidirectional Isolated DC/DC Converter for Energy Routers

Adaptive DMPC-Based Frequency and Voltage Control for Microgrid Deploying a Novel EV-Based Virtual Energy Router

Adaptive DMPC-Based Frequency and Voltage Control for Microgrid Deploying a Novel EV-Based Virtual Energy Router

A Method for Power Flow Calculation in AC/DC Hybrid Distribution Networks Considering the Electric Energy Routers Based on an Alternating Iterative Approach

With the advancement of new power system construction, distribution networks are gradually transforming from being a simple energy receiver and distributor to being an integrated power network that integrates sources, networks, loads, and energy storage with interactive and flexible coupling with the upper-level power grid. However, traditional distribution networks lack active control and distribution capabilities, failing to meet the demands of network transformation and upgrading. To address this issue, this paper proposes a method for solving AC/DC power flow calculation considering an electric energy router (EER) based on an alternating iterative method. Initially, the model for the multi-port EER and three types of power flow models for the AC distribution network, DC distribution network, and EER are constructed. By leveraging the properties of the EER and the hybrid power flow calculation model, a method is proposed for calculating the power flow in the AC/DC hybrid distribution network considering the EER. Finally, by solving the power flow in a medium- and low-voltage AC/DC distribution system, the adaptability of the proposed method is compared. The results demonstrate that the AC/DC hybrid distribution network power flow calculation method established in this paper, which incorporates the EER, possesses high accuracy and adaptability, with an error margin of less than 0.05%.

The application and challenge of energy router in energy internet

AbstractThe energy internet has emerged as a promising area of research in power systems with distributed generation. Similar to an internet router to connect and switch networks, the energy router within the energy internet plays a crucial role to integrate and distribute the energy flow. This paper provides an overview of the application and challenges associated with energy routers in the energy internet. Firstly, the ability of energy routers to bring together multiple energy sources and information is highlighted. Secondly, the discrepancies in power structure when energy routers are utilised in different voltage‐level power grids are discussed. Besides, the roles, structures, and design requirements of energy routers and how they interconnect with the power system, as well as some practical examples of energy router are delved. Finally, the main challenges faced by energy routers are summarised.

Reliability Evaluation of Pilot Virtual-Mesh FREEDMSs by SST Series and Three-Port Power Hub Parallel Energy Routers

Reliability Evaluation of Pilot Virtual-Mesh FREEDMSs by SST Series and Three-Port Power Hub Parallel Energy Routers

Multi-Port Energy Router in Mobile Energy Storage for Emergency Power Outage in Urban Cities

Multi-Port Energy Router in Mobile Energy Storage for Emergency Power Outage in Urban Cities

Optimal scheduling of energy routers based on distributed CAES systems

Abstract With the rise of renewable energy, distributed energy, and other different forms of energy, the architecture and function of the energy router are relatively perfect, for the topology of the energy router itself, different forms of energy in the energy router flow, conversion to realize the large-scale use of distributed energy equipment has also gradually become a hot spot of research. However, there are fewer studies on the energy router with a distributed CAES system to participate in the optimal scheduling of energy for integrated energy systems. Therefore, this paper is based on the operational domain model of an energy router with a distributed CAES system and analyzes the physical characteristics and coupling relationship of non-energy storage components, takes air pressure, temperature, and oil volume as state variables, takes charging, power generation, and heating power as external interfaces, and utilizes internal interface variables such as air quality and flow rate to realize energy storage, flow, and other internal interface variables to realize the communication between energy storage and non-energy storage elements, and finally determine the operation domain of the system. Secondly, the feasible domain of the energy router based on the distributed CAES system is portrayed, and the optimization of the system parameters is guided with the help of the relative distance by establishing the electric and thermal power constraints and the storage state constraints. Finally, the effectiveness of the feasible domain analysis method in the energy router of a distributed CAES system is verified by taking a northern region as an example.

Assessment of the state-of-the-art of solid-state transformer technology: design, control and application

The structure and principle of operation of conventional iron-and-copper conventional transformers has not changed for the past decades largely to its high efficiency and reliability. However, conventional transformers are generally heavy and limited to transformation of AC power only in a unidirectional pattern. However, due to the increasing integration of distributed generation to grid, bidirectional power flow within the present grid systems is now inevitable. This makes solid-state transformer (SST), as a more flexible, portable, and cost-effective alternative, to gain considerable attention in recently. The SST is designed using power electronic components and a high frequency transformer (HFT). As an energy router, SST is crucial to the deployment of internet energy system due to its compact size, improved controllability, resiliency, bidirectional power flow, and variety of applications. Various designs and control approaches have been proposed for the SST to suit various applications. Thus, this paper reviews the extent of research works carried out on the SST vis-à-vis classifications, design, control and applications. The review is centered on establishing the state-of-the-art and identify future research prospects in the design, control, and applications of SST.

A Real-Time Zbus-based Method for Peer-to-Peer Energy Transactions in The Energy Internet

The Energy Internet (EI) has emerged as a promising field within smart grids, addressing capacity limitations and discrepancies in energy resources. It facilitates a peer-to-peer (P2P) energy trading environment for EI prosumers and consumers, reducing reliance on the main grid. To ensure an efficient P2P trading process, it is essential to route energy through the path with minimal power loss optimally. The Energy Router (ER) plays a pivotal role in governing power flow through EI. This paper presents the development of a novel real-time Zbus-based method for directing P2P energy transactions within the EI considering congestion management. The proposed method depends on bus impedance matrix in forming the routing matrix. Firstly, the ER’s structure and function are outlined in relation to the network, and then to design the EI’s topology using an adjacency matrix representation. Secondly, the proposed method methodology is presented in steps and explained on simple 7-bus microgrid. Additionally, a novel congestion management method is integrated into the routing algorithm, considering transmission line loading and available capacity during route selection. Furthermore, the paper applies a power flow technique to the selected routes to optimize power flow performance. The proposed method demonstrates enhanced directness and accuracy compared to existing approaches. Its efficiency is validated by testing a modified IEEE 14-bus system and the standard IEEE 30-bus system. Importantly, the method successfully identifies the minimum loss path, despite the unnecessity of power loss calculations in the routing algorithm. The key contribution of this research lies in providing a comprehensive and practical solution for P2P energy transactions in the EI, showcasing substantial improvements in accuracy, efficiency, and congestion management compared to previous methods.

Current-sensorless model predictive control for DAB converter based on back-flow power optimization

To solve problems such as high back-flow power, low system efficiency and poor dynamic properties of dual-active-full-bridge DC-DC converters in energy routers under traditional single-phase-shift modulation, the present paper introduces a current-sensorless-based model predictive control method combining back-flow power optimization based on Extended-Phase-Shift (EPS) modulation strategy. The transmission power model of the DAB converter is analyzed, taking into account the extended phase shift and the optimal shift comparison combination is found by the Lagrange multiplier method with the return power as the objective function. Then, the cost function is constructed to track the output voltage to achieve model predictive control without a current sensor. Finally, the accuracy and efficiency of the proposed strategy are verified by simulation. The results demonstrate the efficacy of this approach in mitigating system back-flow power and enhancing dynamic performance.

Prediction-Based MIMO Control of a Multiport Magnetic-Coupled Energy Router

Prediction-Based MIMO Control of a Multiport Magnetic-Coupled Energy Router

Bidding strategies for multi-microgrid markets taking into account risk indicators

A large proportion of new energy generation is integrated into the power grid, making it difficult for the power grid system to maintain reliable, stable, and efficient operation. To address these challenges, this article proposes a multiple microgrid hierarchical optimization structure based on energy routers as the core equipment for energy regulation within microgrids. Considering the uncertainty of renewable energy generation within microgrids, a two-layer energy management bidding strategy based on risk indicators is further proposed. In the process of trading, with the goal of maximizing a comprehensive economy, the energy trading model of the distribution network center and energy routers is divided into two sub-objectives for solving. In the first stage, based on the interests and energy supply and demand relationships of each microgrid, a risk assessment model considering wind and solar uncertainty is established to determine the risk preferences and expected returns of each microgrid. In the second stage, the original problem is decomposed into two sub-problems: the minimum cost sub-problem and the maximum transaction volume sub-problem. An asymmetric bargaining mechanism is adopted to determine the production and sales payment of the microgrid containing energy routers based on the contribution values of energy routers in each microgrid. Finally, the rationality and effectiveness of energy routers as an intelligent decision-maker in energy optimization are verified in a three-node system.

Research Review on Multi-Port Energy Routers Adapted to Renewable Energy Access

With the continuous development of renewable energy technologies, both domestically and internationally, the focus of energy research has gradually shifted towards renewable energy directions such as distributed photovoltaics and wind power. The penetration rate of renewable energy generation is constantly increasing, at the same time, the elements in the grid are becoming increasingly complex, and large-scale energy storage, as well as a variety of electricity loads such as electric vehicle charging piles and data centers are gradually appearing. Therefore, traditional distribution methods of the power grid are difficult to ensure the stable operation of the power system and cannot achieve efficient integration of renewable energy. Consequently, some scholars have proposed the concept of an energy internet. Compared to traditional power grids, the energy internet employs more comprehensive power electronics and communication technologies, enabling the interconnection of various new and traditional energy sources, and effectively integrating renewable energy. As the core device in the energy internet, the energy router plays a role in energy transformation and distribution, facilitating multi-information interconnection and multi-energy exchange within the energy internet. At the level of distribution network, the energy router can realize the efficient access of various forms of energy and the flexible control and management, which is of great significance for the optimal operation of distribution network. Against this backdrop, this paper reviews the development and current research status of energy routers, systematically analyzes the typical topologies and related control technologies of multi-port energy routers and summarizes and forecasts key issues and future development trends, aiming to provide thoughts and reference for subsequent related research.

Current Edge-Control Strategy for Multiple Energy Routers Based on Cyber-Energy Dual Modulations

Recently, energy routers have been widely applied in the dc microgrid to achieve the power balance among buses, and the relative control strategies with communication network assumption have been proposed. However, the communication network assumption cannot be satisfied in remote mountainous area and island area. To this end, this paper proposes one communication-free edge-control strategy for energy routers based on cyber-energy dual modulation to achieve power balance without communication network assumption. First, the network structure and system model are introduced, which is an fundamental pretreatment for the subsequent controller design. Second, the cyber-energy dual modulation approach without additional communication line is designed to exchange the information among distributed generations (DGs), which is an indispensable communication environment design for the subsequent controller design. Considering the system model feature and communication environment feature, the periodic dynamic event-triggered-based edge-control strategy is proposed in this paper. Finally, the proposed strategy effectiveness of the energy router is well verified through DC-DC converter experiment set and OPAL-RT test system.

A Novel Wired/Wireless Hybrid Multiport Energy Router for Dynamic EV Energy Internet With Grid-Tied and Islanded Operations

Energy routers (ERs) are indispensable in deploying energy Internet for electric vehicles (EVs), which flexibly handle the power flow regulation. Combined with the excellent characteristic of wireless power transfer (WPT) technology for non-contact energy transmission, this paper proposes a novel wired/wireless hybrid multi-port energy router (HMER) for future EV energy Internet. First, multiple bidirectional power ports are provided to control the power flow among the grid, various DC power sources, and EVs. Moreover, with grid-tied and islanded operations, the proposed HMER enables dynamic wireless energy exchange for EVs on the move. When moving along the energy exchange lane, the EVs can receive power from the HMER and conduct energy feedback, relieving mileage anxiety while creating economic benefits. Further, a mathematical model of the system is derived, and a control algorithm is introduced to perform decoupled power control for each transceiver. Finally, a SIC experimental prototype is constructed to verify the effectiveness of the proposed HMER system. Experimental results prove the transceivers can get bidirectional wireless energy interconnection on the energy exchange lane in both grid-tied mode and islanded mode, and each transceiver can realize independent power regulation.

Multiport Energy Router for DC Grid Clusters

Multiport Energy Router for DC Grid Clusters

Hierarchical Control and Stability Analysis for a Nonisolated Grid-Tied DC Energy Router Integrating Energy Storage and Partial Distributed Generation

Hierarchical Control and Stability Analysis for a Nonisolated Grid-Tied DC Energy Router Integrating Energy Storage and Partial Distributed Generation

An Efficiency Improvement Strategy for Triple-Active-Bridge-Based DC Energy Routers in DC Microgrids

A triple-active bridge (TAB) can be used as a power conversion unit in a three-port DC energy router (DCER) such as a triple-active bridge-based DC energy router (TAB-DCER). The operational loss of a TAB can be seen as a key factor affecting the efficiency of a TAB-DCER. However, the RMS value of the inductor current of the TAB-DCER increases under single-phase shift (SPS) control, and this greatly increases the system operating losses. The use of phase-shifted plus PWM (PS-PWM) control can reduce the RMS value of the inductor current, but its mathematical model is complex, and involves difficult calculations. To address this problem, in the study reported here, we developed an optimal control strategy for the RMS value of the inductor current based on TAB-DCER. First, the working principle of a TAB-DCER under PS-PWM control was analyzed, and a circuit decomposition model was established. Second, the operating modes under PS-PWM control were analyzed, and corresponding expressions of port power and the RMS value of the inductor current were obtained. Third, an optimized mathematical model of the sum of squares of the RMS value of the inductor current of the TAB-DCER was constructed. Finally, a genetic algorithm was used to solve the mathematical model and derive the optimal phase shift angle; this resulted in a lower RMS value of the inductor current in the TAB-DCER and reduced the system operating losses. The simulation and experimental results show that the TAB-DCER used in the present study can reduce operating losses, improve system efficiency, and deliver coordinated power control.