Hybrid Energy Management System Research Articles

A Generalized Approach for Verifying the Emission Benefits of Off-Road Hybrid Mobile Sources

More off-road mobile sources are using hybrid technology, and this research outlines a generalized approach for calculating the differences in emissions between conventional and the complex hybrid designs. The basic approach requires simultaneous measurement of activity and emissions for both designs. The case study for this research was a marine vessel, requiring simultaneously measurement of four diesel engines on both vessels and an additional 126 batteries on the hybrid vessel. Analysis of logged data showed both tugs performed the same five activities and the fraction of time at each load for the main propulsion engines was up to 83 % lower than EPA factors. The in-use emissions were measured at operating loads and total emissions from both vessels were calculated using the new weighting factors. Comparative results showed the hybrid tug had significant reductions: 73 % for PM2.5, 51 % for NOx and 27 % for CO2. Interestingly, most benefits occurred during the transit mode and not the standby mode as was the initial hypothesis. During the transit mode, the hybrid energy management system shut down both large propulsion engines and relied on power from batteries and the auxiliary engines now coupled to the propellers. The basic model developed in this research can be applied to other off-road sources and to estimate various scenarios, including retrofits of existing marine vessels or new designs.

English

English

Integrated Adaptive Cruise Control for Parallel Hybrid Vehicle Energy Management

The possibility to distribute the traction power in a hybrid electric vehicle powertrain over different prime movers and energy recoverability via recuperative braking as well as buffering the energy on rechargeable batteries, lead to the question of how electrical, mechanical or chemical energy should flow among various hybrid components of the powertrain. It is already known that any information about the future driving condition over either a short or long distance horizon is critically valuable to optimize the hybrid strategy. ACC (Adaptive Cruise Control) is a well-known driving assistant system that allows maintaining a safe longitudinal inter-vehicle speed and distance with other traffic objects. Model Predictive Control (MPC) based ACC system inherently predicts the vehicle velocity and acceleration profile. This information together with sensor data can be used to generate the optimal hybrid control especially while approaching a slower vehicle, which means a recuperation potential for the battery and hybrid energy management system. To achieve this, second order curve fitting is applied to the cost function of Equivalent Consumption Minimization Strategy (ECMS) behaviour. The approximated variant is then used to estimate the look-ahead battery energy and if necessary apply pre-discharge strategies to fully benefit the recuperation energy during deceleration manoeuvres.

Multiagent-Based Hybrid Energy Management System for Microgrids

Energy management systems for microgrids (EMS-MG) play an important role in ensuring their stable and economic operation. This paper presents a multiagent-based hybrid EMS-MG (HEMS-MG) with both centralized and decentralized energy control functionalities. Based on this framework, three-level hierarchical energy management strategies are presented, in which a cooperation method with contract net protocol and multifactor evaluation mechanisms are applied. A coordinated energy management framework is realized by the combination of autonomous control of local distributed energy resources at the local level with coordinated energy control at the central level of the microgrid. A novel simulation platform for the HEMS-MG is designed in terms of the client-server frame and implemented under the C++ Builder environment. To prove the effectiveness and benefits of the proposed control system, an example of generation cooperation control of a laboratory microgrid is provided. The simulation results show that the proposed control system is an effective way to manage and optimize microgrid operation.

Operation mode control of a hybrid power system based on fuel cell/battery/ultracapacitor for an electric tramway

This paper focuses on describing a control strategy for a real tramway, in Zaragoza (Spain), whose current propulsion system is to be replaced by a hybrid system based on fuel cell (FC) as primary energy source and batteries and ultracapacitors (UCs) as secondary energy sources. Due to its slow dynamic response, the FC needs other energy sources support during the starts and accelerations, which are used as energy storage devices in order to harness the regenerative energy generated during brakings and decelerations. The proposed energy management system is based on an operation mode control, which generates the FC reference power, and cascade controls, which define the battery and UC reference powers in order to achieve a proper control of the DC bus voltage and states of charge (SOC) of battery and UC. The simulations, performed by using the real drive cycle of the tramway, show that the proposed hybrid system and energy management system are suitable for its application in this tramway.

Sizing optimization, dynamic modeling and energy management strategies of a stand-alone PV/hydrogen/battery-based hybrid system

This paper presents a sizing method and different control strategies for the suitable energy management of a stand-alone hybrid system based on photovoltaic (PV) solar panels, hydrogen subsystem and battery. The battery and hydrogen subsystem, which is composed of fuel cell (FC), electrolyzer and hydrogen storage tank, act as energy storage and support system. In order to efficiently utilize the energy sources integrated in the hybrid system, an appropriate sizing is necessary. In this paper, a new sizing method based on Simulink Design Optimization (SDO) of MATLAB was used to perform a technical optimization of the hybrid system components. An analysis cost has been also performed, in that the configuration under study has been compared with those integrating only batteries and only hydrogen system. The dynamic model of the designed hybrid system is detailed in this paper. The models, implemented in MATLAB-Simulink environment, have been designed from commercially available components. Three control strategies based on operating modes and combining technical-economic aspects are considered for the energy management of the hybrid system. They have been designed, primarily, to satisfy the load power demand and, secondarily, to maintain a certain level at the hydrogen tank (hydrogen energy reserve), and at the state of charge (SOC) of the battery bank to extend its life, taking into account also technical-economic analysis. Dynamic simulations were performed to evaluate the configuration, sizing and control strategies for the energy management of the hybrid system under study in this work. Simulation results show that the proposed hybrid system with the presented controls is able to provide the energy demanded by the loads, while maintaining a certain energy reserve in the storage sources.