Yanzhu Ye

A modular multilevel converter based battery-ultracapacitor hybrid energy storage system for photovoltaic applications

To smooth the output power of a Photovoltaic (PV) system, the integration of the Hybrid Energy Storage System (HESS) has been considered as an effective solution. In this paper, a Modular Multilevel Converter (MMC) is proposed for the HESS that combines battery and UltraCapacitor (UC), and a two-layer framework is proposed to control the proposed HESS system. Compared to traditional HESSs and other MMCs for HESS applications, the proposed MMC based HESS increases the overall system efficiency, reduces the cost of dc side passive components, and is favorable for grid energy storage systems. Simulation results are provided to verify the theoretical analysis.

Adaptive Control of Hybrid Ultracapacitor-Battery Storage System for PV Output Smoothing

The integration of hybrid energy storage system (ESS) with PV has been considered an effective solution for PV power smoothing, e.g. the hybrid Ultracapacitor (UC)-Battery storage system. This paper proposes a fuzzy-logic-based adaptive power management system for smoothing PV power output, which manages the power sharing between the UC and Battery system. In this method, the real-time system dynamics are reflected in the adaptive control parameter settings. At the same time this method effectively considers the characteristics and operational constraints of the energy storage devices, e.g. SOC limit, charge/discharge current limit, etc., in order to sustain the system operation. A hybrid PV/UC/Battery power system is modeled by Matlab/Simulink. The simulation studies are performed to demonstrate the effectiveness and advantages of the proposed control method in PV fluctuation suppression, sustainable system operation, energy storage performance.Copyright

A multi-layer optimal chiller operation management framework

This work targets on the chiller plant operation management for a large campus building cooling load. In this paper a multi-layer optimal chiller operation management framework is proposed to operate various chiller units to meet the system cooling load while reduce the system operation cost. The first layer is the day-ahead 24-hour chiller operation planning layer which optimizes multiple chiller sequencing and chillers loading. The second real-time dispatching layer effectively addresses load forecasting uncertainties in real-time. The load uncertainty is solved hierarchically through two steps of approaches. An efficient and accurate system modeling framework for optimization is formulated with mixed-integer linear expressions to reduce the computational complexity. The effectiveness of this proposed management framework is demonstrated for an actual chiller plant operation in university campus. Simulation analyses validate that the proposed method can effectively address various levels of forecast uncertainty and reduce the operation cost.

A robust control approach to smooth output power of wind units using Hybrid Storage Systems considering state of charge

Output power smoothing of wind units is one of the attractive topics in renewable energies. This paper presents a novel method to control Hybrid Storage Systems (HSSs) for smoothing the output power of wind units. HSS consists of a lead-acid battery and an Electric Double-Layer Capacitor (EDLC), each one equipped with a DC/DC converter, connected to the grid through a DC/AC converter. Proposed control scheme applies mode switching strategy, in which different operation modes are carefully designed under different HSS status. This method takes the state of charge (SoC) of both battery and EDLC into consideration. Performance of the proposed control method is investigated using simulations in MATLAB-Simulink. Results show robustness and effectiveness of the proposed control method.