Dynamic energy management of micro grids using battery super capacitor combined storage
01 Dec 2012-pp 1078-1083
TL;DR: In this paper, the authors proposed a combined energy storage using batteries and super capacitors with high energy and power density for the photovoltaic (PV) based micro grid.
Abstract: The energy flow between source and the load of micro grid must be balanced to have a constant dc grid voltage. Due to intermittency in the natural sources and the variations in load, energy balance operation demands storage. The commonly preferred choice of energy storage in micro grid is valve regulated lead acid batteries. When batteries are used as energy storage, due to its low power density, the charge and discharge rate is low. It causes severe stress on the battery under quick load fluctuations and results in increase in the number of charge/discharge cycles. Hence, the lifetime of the battery reduces. The super capacitors have high power density and it can react speedily to quick load fluctuations. However, super capacitors alone cannot be used as energy storage as it cannot supply load for a longer time. Hence, this paper proposes a combined energy storage using batteries and super capacitors with high energy and power density. The photovoltaic (PV) based micro grid with combined energy storage is designed and the control strategy is validated for different atmospheric and load conditions.
Citations
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TL;DR: In this paper, a simple novel control strategy is designed and analyzed for a hybrid energy storage system (HESS), where batteries are used to balance the slow changing power surges, whereas super-capacitors (SC) are used by diverting the power surges to the SC system.
Abstract: In this paper, a simple novel control strategy is designed and analyzed for a hybrid energy storage system (HESS). In the proposed method, batteries are used to balance the slow changing power surges, whereas supercapacitors (SC) are used to balance the fast changing power surges. The main advantage of the proposed control strategy is that, the slow response of battery system including dynamics of battery, controller, and converter operation, is overcome by diverting the power surges to the SC system. The proposed method inherits charge/discharge rate control to improve the life span and reduce the current stresses on battery. The proposed method features less computational burden as it uses simple control strategy. The detailed experimental results presented validate the proposed control strategy for sudden changes in photovoltaic (PV) generation and load demand.
295 citations
Cites background or methods from "Dynamic energy management of micro ..."
...The block diagram of conventional control strategy [7] is shown in Fig....
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...Batteries have high energy density but low power density, giving low charge/discharge rates [7]....
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...To demonstrate the performance of the proposed control strategy, it is compared with conventional strategy [7] for the following cases: 1) step decrease in load demand; 2) step increase in load demand; 3) step increase in PV generation; and 4) step decrease in PV generation....
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...[7] have proposed HESS for microgrid applications....
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TL;DR: A unified energy management scheme is proposed for renewable grid integrated systems with battery-supercapacitor hybrid storage that enables the real power transfer along with ancillary services such as current harmonic mitigation, reactive power support, and power factor improvement at the point of common coupling.
Abstract: In this paper, a unified energy management scheme is proposed for renewable grid integrated systems with battery–supercapacitor hybrid storage. The intermittent nature of renewable-energy resources (RES), coupled with the unpredictable changes in the load, demands high-power and high-energy-density storage systems to coexist in today's microgrid environment. The proposed scheme dynamically changes the modes of renewable integrated systems based on the availability of RES power and changes in load as well. The participation of battery–supercapacitor storage to handle sudden/average changes in power surges results in fast dc link voltage regulation, effective energy management, and reduced current stress on battery. In addition, the proposed energy management scheme enables the real power transfer along with ancillary services such as current harmonic mitigation, reactive power support, and power factor improvement at the point of common coupling. The proposed scheme is validated through both simulation and experimental studies.
264 citations
Cites methods from "Dynamic energy management of micro ..."
...The performances of both control schemes (the proposed scheme and the scheme in [19] called as scheme-I) are given in Table V....
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...A control strategy is devised in [19] to balance the power flow in a dc microgrid...
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TL;DR: In this paper, a hybrid energy storage system (HESS), which combines battery for long-term energy management and supercapacitor for fast dynamic power regulation, is proposed for remote area renewable energy power supply systems.
233 citations
TL;DR: A renewable energy-based dc micro-grid with hybrid energy storage, consisting of battery and ultracapacitor, is investigated and MATLAB/Simulink simulation results are presented to validate the proposed system operation strategy and the energy management method.
Abstract: A renewable energy-based dc micro-grid with hybrid energy storage, consisting of battery and ultracapacitor, is investigated. To achieve high penetration depth of renewable sources into the utility grid, a novel system operation strategy and the corresponding energy management method is proposed. In the operation strategy, the ultracapacitor unit works as the sole voltage source of the micro-grid to support the dc link in both connected and islanding mode. The micro-grid is controlled to deliver/absorb predefined amount of power to/from the utility grid during connected mode and zero during islanding mode. This design will certainly simplify the power dispatching algorithm of the power system and increase the possibility of including large quantities of micro-grids into the utility grid. The energy management method is dedicated to conducting the net power of the micro-grid effectively. The net power is separated into high- and low-frequency components. The high-frequency power is suppressed by the ultracapacitor automatically and the low frequency power is shared by the battery and an adjustment unit. A small-scale dc micro-grid structure with a single dc link is considered for investigation. MATLAB/Simulink simulation results are presented to validate the proposed system operation strategy and the energy management method.
160 citations
TL;DR: In this article, a new control scheme is proposed to control the power sharing between batteries and supercapacitors to match the generation-demand mismatch and regulate the grid voltage, which not only improves the dc grid voltage regulation capability but also reduces the stress levels on the battery and hence increases the life span of the battery.
Abstract: The power generation from renewable power sources is variable in nature, and may contain unacceptable fluctuations in case of the wind power generation. High fluctuations in power generation may negatively impact the voltage stability of the microgrid. This problem can be alleviated by using hybrid energy storage system consisting of batteries and supercapacitors (SCs) at dc grid. A new control scheme is proposed to control the power sharing between batteries and SCs to match the generation-demand mismatch and hence to regulate the grid voltage. In the proposed control strategy, the SC supplies error component of the battery current in addition to the fast transient power demand. This added feature not only improves the dc grid voltage regulation capability but also reduces the stress levels on the battery and hence increases the life span of the battery. The main advantage of the scheme is that, the uncompensated power due to slow dynamics of the battery is diverted to the SC and keeps the state of charge within the limits for longer duration, as compared to the conventional strategy. The proposed scheme is validated through detailed experimental studies.
148 citations
References
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Proceedings Article•
22 Oct 2008
535 citations
TL;DR: In this article, a sequence of actions and conditions to be checked during service restoration in the low voltage area are identified and tested through numerical simulation, and the need of storage devices is addressed in order to ensure system stability, achieve robustness of operation, and not jeopardize power quality.
Abstract: Under normal operating conditions, a MicroGrid is interconnected with the medium voltage network; however, in order to deal with black start and islanded operation following a general blackout, an emergency operation mode must be envisaged. A sequence of actions and conditions to be checked during the restoration stage are identified and tested through numerical simulation. Voltage and frequency control approaches, inverter control modes, and the need of storage devices are addressed in this paper in order to ensure system stability, achieve robustness of operation, and not jeopardize power quality during service restoration in the low voltage area
269 citations
"Dynamic energy management of micro ..." refers methods in this paper
...To achieve that, micro grid central controller at the grid centre and number of local controllers at each load centre are being used [2]....
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30 Sep 2008
TL;DR: In this article, the role of the supercapacitor in a PV energy control unit (ECU) is investigated by using Matlab/Simulink models, where the ECU monitors and optimizes the power flow from the PV to the battery-supercapacitors hybrid and the load.
Abstract: Most of the stand-alone photovoltaic (PV) systems require an energy storage buffer to supply continuous energy to the load when there is inadequate solar irradiation. Typically, Valve Regulated Lead Acid (VRLA) batteries are utilized for this application. However, supplying a large burst of current, such as motor startup, from the battery degrades battery plates, resulting in destruction of the battery. An alterative way of supplying large bursts of current is to combine VRLA batteries and supercapacitors to form a hybrid storage system, where the battery can supply continuous energy and the supercapacitor can supply the instant power to the load. In this paper, the role of the supercapacitor in a PV energy control unit (ECU) is investigated by using Matlab/Simulink models. The ECU monitors and optimizes the power flow from the PV to the battery-supercapacitor hybrid and the load. Three different load conditions are studied, including a peak current load, pulsating current load and a constant current load. The simulation results show that the hybrid storage system can achieve higher specific power than the battery storage system.
254 citations
"Dynamic energy management of micro ..." refers background in this paper
...3 − 3 hours in micro grid applications [3]....
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15 Jun 2008
TL;DR: In this article, a flow-battery supercapacitor hybrid energy storage system is proposed to absorb high frequency power surges in a wind farm, which takes advantage of the two complementary technologies to provide large power and energy capacities.
Abstract: An energy storage system (ESS) in a wind farm is required to be able to absorb wind power surges during gusts, and have sufficient energy storage capacity to level wind fluctuations lasting for longer periods. ESS using a single technology, such as batteries, or supercapacitors, will have difficulties providing both large power and energy capacities. This paper proposes a flow-battery supercapacitor hybrid ESS, which takes advantage of the two complementary technologies to provide large power and energy capacities. The flow-battery is directly coupled to the WTG dc bus while the supercapacitor has a dc/dc IGBT converter interface. The dc bus voltage varies within a certain limit determined by the variable battery terminal voltage. With the supercapacitor absorbing high frequency power surges, the battery power rating, degree of discharge, and power losses are all reduced. Therefore the battery in the hybrid ESS has low cost and high longevity; and the system overall efficiency is improved.
182 citations
"Dynamic energy management of micro ..." refers background in this paper
...As the DOD of batteries is high, the lifetime of the batteries reduces [4]....
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TL;DR: The proposed micro-wind energy conversion system with battery energy storage is used to exchange the controllable real and reactive power in the grid and to maintain the power quality norms as per International Electro-Technical Commission IEC-61400-21 at the point of common coupling.
Abstract: In the micro-grid network, it is especially difficult to support the critical load without uninterrupted power supply. The proposed micro-wind energy conversion system with battery energy storage is used to exchange the controllable real and reactive power in the grid and to maintain the power quality norms as per International Electro-Technical Commission IEC-61400-21 at the point of common coupling. The generated micro-wind power can be extracted under varying wind speed and can be stored in the batteries at low power demand hours. In this scheme, inverter control is executed with hysteresis current control mode to achieve the faster dynamic switchover for the support of critical load. The combination of battery storage with micro-wind energy generation system (μ WEGS), which will synthesize the output waveform by injecting or absorbing reactive power and enable the real power flow required by the load. The system reduces the burden on the conventional source and utilizes μ WEGS and battery storage power under critical load constraints. The system provides rapid response to support the critical loads. The scheme can also be operated as a stand-alone system in case of grid failure like a uninterrupted power supply. The system is simulated in MATLAB/SIMULINK and results are presented.
99 citations
"Dynamic energy management of micro ..." refers background in this paper
...The imbalance power is given to storage element during energy surplus conditions and during deficit, the already stored energy can be drawn [10]....
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