Hierarchical Control of Hybrid Energy Storage System in DC Microgrids

Abstract

Hybridization of energy storages (ESs) with different characteristics takes advantages of all ESs. Centralized control with high/low pass filter (HPF/LPF) for system net power decomposition and ESs power dispatch is usually implemented in hybrid energy storage system (HESS). In this paper, hierarchical control of HESS, comprised of both centralized and distributed control, is proposed to enhance system reliability. The conventional HESS centralized control is refined with implementations of online iteration, secondary voltage regulation and autonomous state of charge (SoC) recovery. ESs power references are generated iteratively to maximize the utilizations of ESs ramp rates and power capacities. Secondary voltage regulation and autonomous SoC recovery are applied to minimize bus voltage deviation and limit slack terminal SoC variation, respectively. In case of communication failure, a novel algorithm for HESS distributed control is proposed to retain system operation. Bus voltage is regarded as the global indicator for system power balance and droop relationships are imposed for ESs control. System net power decomposition and ESs power dispatch are realized with localized LPFs. SoC recovery in distributed control is implemented by tuning the threshold voltage of slack terminal. A lab-scale DC microgrid is developed to verify the proposed hierarchical control of HESS.Index Terms-Hybrid energy storage system, DC microgrid, hierarchical control, net power decomposition, ESs power dispatch.

Review of Ship Microgrids: System Architectures, Storage Technologies and Power Quality Aspects

“…The hybrid energy storage systems are also proposed and developed in recent years to exploit the advantages of multiple energy storage technologies to fulfil various needs of microgrids [40][41][42]. The most commonly proposed hybrid ESS uses batteries and supercapacitors, hence this ESS has the benefits from high energy density of batteries and high power density of supercapacitors [40,41].…”

Common Grounded H-Type Bidirectional DC-DC Converter with a Wide Voltage Conversion Ratio for a Hybrid Energy Storage System

“…Generally, a HESS is mainly composed of high power density super-capacitors (SCs) and high energy density batteries. It is desirable to balance the steady-state power imbalance by the batteries and compensate for the transient power imbalance by an SC with fast dynamics [12][13][14]. As a result, the degradation impact on the batteries caused by sudden load changes can be greatly reduced, and the dynamic response of the whole DC micro-grid can also be improved [15,16].…”

Switched optimization control of power allocation of hybrid energy storage systems

“…There are many efforts to study the power allocation and management problem of the HESS, and a rich of results have been obtained . For example, according to the complementary characteristics of different energy storage units, the authors in one study put forward a HESS consisting of an ultracapacitor and a battery to raise lifecycle of the storage system.…”

“…Recently, the authors in Hu et al comparatively examined 3 different electrochemical storage devices, ie, a Li‐ion battery, an ultracapacitor, and a dual buffer, in a framework of simultaneous optimal ESS sizing and energy management for a hybrid bus powertrain. The available results showed that the HESS had better operation and economic performance for frequent, rapid power and energy changes in renewable powered grid systems . Compared to these results focusing on the mechanism analysis of energy storage processes, there is a little work considering explicitly the physical constraints of storage units and uncertain switching features resulted from the charging and discharging modes during designing power allocation controllers of the HESS.…”