Hierarchical Control Strategy of On-board DC Microgrid

In the last several years, the coordination control of hybrid AC/DC microgrids (HMGs) has been gaining increasingly more attention. However, most of these discussions are focused on single-bus HMGs whose AC or DC bus is not sectionalized by AC or DC breakers. Compared with these single-bus HMGs, the bus-sectionalized HMG has more flexible topologies, more diverse operation modes, and consequently higher service reliability. However, meanwhile, these benefits also bring challenges to the stable operation of bus-sectionalized HMGs, particularly for mode switching. Relying on the national HMG demonstrative project in Shaoxing, China, this paper makes efforts to present the hierarchical control paradigm of a typical bus-sectionalized HMG toward standardization. The test results demonstrate that the proposed system provides seamless switching and uninterrupted power supply without controller reconfiguration among different operation modes. The operational data are also brought forth and analyzed to provide significant and useful experiences for designing and developing similar HMGs in the future.

Download Full-text

Novel Control Strategy for Enhancing Microgrid Operation Connected to Photovoltaic Generation and Energy Storage Systems

Electronics ◽

10.3390/electronics10111261 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1261

Author(s):

Dina Emara ◽

Mohamed Ezzat ◽

Almoataz Y. Abdelaziz ◽

Karar Mahmoud ◽

Matti Lehtonen ◽

...

Keyword(s):

Energy Storage ◽

Control Strategy ◽

Voltage Stability ◽

Storage Systems ◽

Voltage Source ◽

Stable Operation ◽

Energy Storage Systems ◽

Dc Microgrid ◽

Photovoltaic Generation ◽

Dc Voltage

Recently, the penetration of energy storage systems and photovoltaics has been significantly expanded worldwide. In this regard, this paper presents the enhanced operation and control of DC microgrid systems, which are based on photovoltaic modules, battery storage systems, and DC load. DC–DC and DC–AC converters are coordinated and controlled to achieve DC voltage stability in the microgrid. To achieve such an ambitious target, the system is widely operated in two different modes: stand-alone and grid-connected modes. The novel control strategy enables maximum power generation from the photovoltaic system across different techniques for operating the microgrid. Six different cases are simulated and analyzed using the MATLAB/Simulink platform while varying irradiance levels and consequently varying photovoltaic generation. The proposed system achieves voltage and power stability at different load demands. It is illustrated that the grid-tied mode of operation regulated by voltage source converter control offers more stability than the islanded mode. In general, the proposed battery converter control introduces a stable operation and regulated DC voltage but with few voltage spikes. The merit of the integrated DC microgrid with batteries is to attain further flexibility and reliability through balancing power demand and generation. The simulation results also show the system can operate properly in normal or abnormal cases, thanks to the proposed control strategy, which can regulate the voltage stability of the DC bus in the microgrid with energy storage systems and photovoltaics.

Download Full-text

Hierarchical energy management strategy considering switching schedule for a dual-mode hybrid electric vehicle

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/09544070211029791 ◽

2021 ◽

pp. 095440702110297

Author(s):

Hui Liu ◽

Rui Liu ◽

Riming Xu ◽

Lijin Han ◽

Shumin Ruan

Keyword(s):

Fuel Consumption ◽

Energy Management ◽

Control Strategy ◽

Power Distribution ◽

Hybrid Electric Vehicle ◽

Hierarchical Control ◽

Management Problem ◽

Energy Management Strategy ◽

Dual Mode ◽

Hybrid Electric

Energy management strategies are critical for hybrid electric vehicles (HEVs) to improve fuel economy. To solve the dual-mode HEV energy management problem combined with switching schedule and power distribution, a hierarchical control strategy is proposed in this paper. The mode planning controller is twofold. First, the mode schedule is obtained according to the mode switch map and driving condition, then a switch hunting suppression algorithm is proposed to flatten the mode schedule through eliminating unnecessary switch. The proposed algorithm can reduce switch frequency while fuel consumption remains nearly unchanged. The power distribution controller receives the mode schedule and optimizes power distribution between the engine and battery based on the Radau pseudospectral knotting method (RPKM). Simulations are implemented to verify the effectiveness of the proposed hierarchical control strategy. For the mode planning controller, as the flattening threshold value increases, the fuel consumption remains nearly unchanged, however, the switch frequency decreases significantly. For the power distribution controller, the fuel consumption obtained by RPKM is 4.29% higher than that of DP, while the elapsed time is reduced by 92.53%.

Download Full-text

Bus Voltage Control Strategy for Low Voltage DC Microgrid Based on AC Power Grid and Battery

2017 IEEE International Conference on Energy Internet (ICEI) ◽

10.1109/icei.2017.68 ◽

2017 ◽

Cited By ~ 4

Author(s):

Zhongtian Zhao ◽

Jian Hu ◽

Hongtao Chen

Keyword(s):

Control Strategy ◽

Low Voltage ◽

Power Grid ◽

Voltage Control ◽

Voltage Control Strategy ◽

Dc Microgrid ◽

Ac Power ◽

Bus Voltage

Download Full-text

A Novel Hierarchical Control Strategy for Low-Voltage Islanded Microgrids Based on the Concept of Cyber Physical System

Energies ◽

10.3390/en11071835 ◽

2018 ◽

Vol 11 (7) ◽

pp. 1835 ◽

Cited By ~ 1

Author(s):

Qiuxia Yang ◽

Dongmei Yuan ◽

Xiaoqiang Guo ◽

Bo Zhang ◽

Cheng Zhi

Keyword(s):

Control Strategy ◽

Physical System ◽

Reactive Power ◽

Low Voltage ◽

Hierarchical Control ◽

Physical Layer ◽

Cyber Physical System ◽

Droop Control ◽

Control Effect ◽

Consensus Control

Based on the concept of cyber physical system (CPS), a novel hierarchical control strategy for islanded microgrids is proposed in this paper. The control structure consists of physical and cyber layers. It’s used to improve the control effect on the output voltages and frequency by droop control of distributed energy resources (DERs), share the reactive power among DERs more reasonably and solve the problem of circumfluence in microgrids. The specific designs are as follows: to improve the control effect on voltages and frequency of DERs, an event-trigger mechanism is designed in the physical layer. When the trigger conditions in the mechanism aren’t met, only the droop control (i.e., primary control) is used in the controlled system. Otherwise, a virtual leader-following consensus control method is used in the cyber layer to accomplish the secondary control on DERs; to share the reactive power reasonably, a method of double virtual impedance is designed in the physical layer to adjust the output reactive power of DERs; to suppress circumfluence, a method combined with consensus control without leader and sliding mode control (SMC) is used in the cyber layer. Finally, the effectiveness of the proposed hierarchical control strategy is confirmed by simulation results.

Download Full-text