Lead acid battery storage configurations for improved availablecapacity

Battery storage is a crucial element in alternative energy and electric vehicle systems. Three battery storage configurations: a conventional; a parallel; and a dual, were analyzed for both shallow cycle and deep cycle lead-acid batteries to determine if capacity improvement is achievable. Daily profiles for the weekly irradiance, daily loads, and ambient temperature are simulated. Cycle tests were performed monthly to determine the effect each configuration had on the available battery capacity. Results for each battery type differ. Available capacity was improved using the parallel configuration with shallow cycle batteries and the dual configuration with deep cycle batteries     

Lead–acid battery chemistry adapted for hybrid electric vehicle duty

Lead–acid batteries that are intended for traditional tasks such as SLI or deep cycle duty do not perform well in hybrid electric vehicles (HEVs). With the benefit of a few straightforward modifications in design, however, batteries deploying lead–acid chemistry can satisfy the performance requirements of power-assist HEVs in both bench- and in-vehicle tests.     

模块化多电平复合变换器电池储能系统容错控制策略

模块化多电平复合变换器电池储能系统(modular multi-level hybrid convert-battery energy storage system,MMHC-BESS)适用于中低压电网,有利于解决可再生能源并网问题.但随着子模块数量的增加,系统的可靠性面临着巨大的挑战.为增强储能系统的容错运行能力,针...     

Optimisation of a photovoltaic battery ultracapacitor hybrid energy storage system

Autonomous photovoltaic panels are intermittent sustainable energy sources which require energy storage to balance generation and demand, as photovoltaic generation is time and weather dependent. Traditionally batteries are the most common storage technology for photovoltaic systems. Photovoltaic batteries can encounter extended periods of low State of Charge (SOC), resulting in sulphation and stratification, reducing battery lifetime.Standalone photovoltaic systems are often used in remote areas away from the national grid for water irrigation system, requiring dc motor starting resulting in high inrush current, cathodic protection systems for oil and gas pipelines, emergency phones, warning signs, and telecommunication repeater stations, resulting in pulse discharging of the battery. A combination of depleted battery SOC and high burst current can result in premature loss of load due to stringent battery Low Voltage Disconnect (LVD) limits implemented by the battery management system.A combination of Valve Regulated Lead Acid (VRLA) batteries and ultracapacitors in a Hybrid Energy Storage System (HESS), which increases the power density of the overall system, is examined. Operating the ultracapacitor bank under high power conditions reduces the strain of large current extraction from the battery bank. The addition of the ultracapacitor bank presents the need for a methodology to optimise the photovoltaic system to prevent excess battery storage.This paper outlines the methodology utilised to optimise the combination of photovoltaic panels, batteries, and ultracapacitors for a given solar radiation and load profile employing Matlab software.     

A simplified model for estimating the monthly performance of autonomous wind energy systems with battery storage

This paper presents a simplified algorithm to estimate the monthly performance of autonomous small-scale wind energy systems with battery storage. The novel model is drawn based on the simulation results, using eight-year long hour-by-hour measured wind speed data from five different locations throughout the world. An hourly constant load profile is used. The renewable energy simulation program (ARES) of the Cardiff School of Engineering is used. The ARES simulates the battery state of voltage (SoV) and is able to predict the system performance.The monthly performance values obtained from the simulations are plotted against increasing energy to load ratios for varying battery storage capacities to obtain performance curves. The novel method correlates the monthly system performance with the parameters of the Weibull distribution function, thus offering a universal use. The monthly performance curves are mathematically represented using a 2-parameter function. The novel method is validated by comparing the simulated performance values with those estimated from the simplified algorithm. The standard errors calculated in estimation of the system performance using the simplified algorithm are further presented for each battery capacity.     

规模化电池储能系统的无功功率控制策略研究

无功功率补偿是电池储能系统并网运行时的重要应用。电池储能系统主要包括电池组、变流器以及设备监控系统等。电池储能用变流器可向电网提供无功功率。文章提出了规模化电池储能电站中各储能机组间的无功功率分配方法。采用仿真软件对电池储能系统的无功功率分配策略进行仿真分析,并基于张北储能试验基地的电池储能机组实例验证了控制策略的有效性。     

Simulations of economical and technical feasibility of battery and flywheel hybrid energy storage systems in autonomous projects

This paper deals with the feasibility of a Renewable Energy Sources (RES)-based stand-alone system for electricity supply based on a Flywheel Energy Storage System (FESS) located on the Greek Island of Naxos. The innovative use of flywheels in parallel connection with electrochemical batteries, as an integrated storage device in the same power plant, was selected to be simulated as it is a necessary buffer covering the load of a typical house. The optimal configuration for the electromechanical connection between the electrochemical batteries and flywheels is also considered in this study. Operational characteristics of the new storage systems were estimated and used in the simulations, while the financial aspects of the projects finalized using hand-made calculations and the HOMER software was used only for the energy calculations. It was found that an off-grid project using advanced and totally “green” technologies is possible and comparable to more conventional RES-based systems, in terms of energy and economical feasibility. Finally, it can be concluded that systems with low price flywheels are equivalent to those with electrochemical batteries.     

The effect of pumped storage and battery energy storage systems onhydrothermal generation coordination

A simulated battery energy storage (BES) system is considered for integration into Taiwan Power Company System to study the economic benefits of the BES. The system had a pumped storage power plant with four units. The authors applied multipass dynamic programming to the solution of the short term hydrothermal coordination problem considering pumped storage and battery energy storage systems. The algorithm can quickly converge to an optimal generation schedule while achieving the minimum production cost of power systems. Substantial savings of memory and CPU time were realized by using this efficient algorithm. The load, committed units, and available water usage data from 9:00 PM June 17, 1988 to 9:00 PM June 24 were used to test this algorithm. Results showed that within 20 minutes on a PC/386 this algorithm could find the optimal generation schedule of all the units and the switching time of the BES while satisfying all the constraints     

针对风电波动抑制的电池储能SOC鲁棒优化模型

针对风电系统输出功率波动问题,研究了基于风电波动异常数据判断及波动幅度情景划分的,能够有效抑制风电波动的电池储能系统SOC鲁棒优化模型。研究电网调度需求、风电功率预测及风电波动数据特性,建立了风电波动异常数据鲁棒判别模型,为风电波动场景划分提供数据支持;研究不同风电波动幅度场景电池储能系统SOC适应性指标,建立了在不同风险容许度下的SOC鲁棒优化模型;研究基于风电波动数据及其对应的电池储能系统SOC历史数据的SOC鲁棒优化模型求解方法,建立了基于χ2散度函数的SOC鲁棒优化算法;根据风电出力波动及电池储能系统特性,建立了基于特定区域电网的电力系统仿真模型,并根据风电波动特性对电池储能系统SOC优化结果进行仿真分析。仿真结果表明,文章针对风电波动抑制建立的电池储能SOC鲁棒优化模型,对风电波动幅度具有明显的抑制效果,提升了电网运行稳定性。     

Optimal sizing of battery storage for hybrid (wind+diesel) power systems

Hourly mean wind-speed data for the period 1986–1997 [except the years 1989 (some data is missing) and 1991 (Gulf War)] recorded at the solar radiation and meteorological monitoring station, Dhahran (26°C 32′ N, 50° 13′ E), Saudi Arabia, have been analyzed to investigate the optimum size of battery storage capacity for hybrid (wind+diesel) energy conversion systems at Dhahran. The monthly average wind speeds for Dhahran range from 4.12 to 6.42 m/s. As a case study, the hybrid system considered in the present analysis consists of two 10 kW Wind Energy Conversion Systems (WECS), together with a battery storage system and a diesel back-up. The yearly and monthly average energy generated from the above hybrid system have been presented. More importantly, the study explores the impact of variation of battery storage capacity on hybrid power generation. The results exhibit a trade-off between size of the storage capacity and diesel power to be generated to cope with specific annual load distribution [41,500], and for given energy generation from WECS. The energy to be generated from the back-up diesel generator and the number of operational hours of the diesel system to meet a specific annual electrical energy demand have also been presented. The diesel back-up system is operated at times when the power generated from WECS fails to satisfy the load and when the battery storage is depleted. The present study shows that for economic considerations, for optimum use of battery storage and for optimum operation of diesel system, storage capacity equivalent to one to three days of maximum monthly average daily demand needs to be used. It has been found that the diesel energy to be generated without any storage is considerably high; however, use of one day of battery storage reduces diesel energy generation by about 35%; also the number of hours of operation of the diesel system are reduced by about 52%.     

Hybridization strategies of power-to-gas systems and battery storage using renewable energy

In this paper, the hybrid concept to use renewable electricity to produce hydrogen with an electrolyser in combination with a battery is introduced and analysed. This hybrid system opens the possibility to optimise operation and to increase operation times of the system and thus to improve the techno-economic performance. To analyse the performance, a model has been developed, which designs and operates a single or hybrid power-to-gas system in a cost optimal manner. The underlying method is a mixed integer linear programming (MILP) approach, which minimises total system costs. The cost optimisation modelling is performed by a case study for a hybrid electrolyser/battery system directly coupled with a large PV power plant without grid connection. The results show, that batteries can support electrolyser operation in a reasonable way. This is however associated with higher hydrogen production costs and not competitive compared to the installation of additional electrolyser capacity or curtailment of electricity.     

兼顾储能系统热管理与电池寿命的可再生能源储能电站经济调度

可再生能源储能电站的长期稳定运行与储能系统的热量管理息息相关,合理的热量管理策略能够保障储能电站的经济性与安全性.为了合理有效地进行储能系统热量管理,本文综合电池寿命成本,以日内实时调度的最高净盈利作为优化目标,提出了考虑热量管理与电池寿命损耗成本的储能电站调度策略.并利用分片McCormick方法将双线性项精细线性化...     

Application of regenerative fuel cells for space energy storage: a comparison to battery systems

A major advantage of regenerative fuel cells compared with battery systems arises from the decoupling of their rated power and their capacity, which determines the storage system. The mass of battery systems is related to the energy stored, whereas the masses of regenerative fuel cell systems are mainly determined by their rated power. On the other hand, average power and total energy are not independent variables, since they are correlated by the period of discharge of the electrochemical cells. Thus a comparison of the different approaches to storage can be given, by evaluating system masses as a function of power requirement and period of discharge. Since space power applications are considered, the charging and discharging periods can be expressed in terms of orbit altitudes.     

The UltraBattery—A new battery design for a new beginning in hybrid electric vehicle energy storage

The UltraBattery, developed by CSIRO Energy Technology in Australia, is a hybrid energy storage device which combines an asymmetric super-capacitor and a lead–acid battery in single unit cells. This takes the best from both technologies without the need for extra, expensive electronic controls. The capacitor enhances the power and lifespan of the lead–acid battery as it acts as a buffer during high-rate discharging and charging, thus enabling it to provide and absorb charge rapidly during vehicle acceleration and braking.     

新能源系统储能用铅酸电池使用寿命的影响因素分析

分析了储能铅酸电池的失效模式和影响其使用寿命的内在因素、外在因素以及综合因素。电池内在因素包括电池极板、隔板等部件的质量和电池制造工艺;电池运行的外部因素包括环境温度、欠充电、过放电以及浮充电压的选择等;电池内在因素与外部因素发生综合作用的情况主要包括板栅腐蚀,内部热量失控以及酸分层等。根据储能铅酸电池特殊的工作条件导致的失效问题,结合寿命影响因素的分析,提出了延长寿命的各种对策。     

Large energy storage systems for utilities

In addition to the capacity on line, electric networks usually need 8–10 per cent of their installed capacity readily available to handle load variations. Thermal storage of energy as pressurised saturated hot water has done this job for years, but only on a small scale because of cost limitation of the steel pressure vessel. This paper shows that steel lined cavities deep underground, using the rock to provide containment, are economical and practical in large capacities for this energy storage. By reducing the cavity pressure, steam is flashed from the hot water and used to drive peaking turbines when needed; at low load periods surplus steam is condensed in the water to recharge the vault. The saturation pressure of the hot water is borne by the overburden pressure of the rock formation in which the storage vault is prepared. At usual steam plant saturation temperatures the effective storage density is in the range of 18–21 electric kWh/m³ of storage volume, which is 20–50 times the capacity of the usual pumped hydro systems. Recovery of stored energy ranges from 75–90 per cent. The cost of a facility to deliver 1000 MW of peaking power for 10 h would fall in the range of $250–350 million, including indirect costs, interest, etc. The underground facilities represent about 40 per cent of the cost: the balance is for conventional generating and steam plant equipment.     

Experimental results for hybrid energy storage systems coupled to photovoltaic generation in residential applications

An experimental solar-hydrogen powered residence simulator was built and tested. The system consisted of a solar photovoltaic array connected to an electrolyzer which produced hydrogen as a means of energy storage. The hydrogen was used to produce electricity in a fuel cell that operated in parallel with a battery to meet dynamic power demand similar to that found in residential applications. The study demonstrated the technical feasibility of operating such a system under the simultaneous dynamics of solar input and load. Limitations of current fuel cell and electrolyzer designs, as they pertain to both power delivery and energy storage, were identified. The study also established the need to understand and address dynamic performance in the design and application of solar-hydrogen reversible fuel cell hybrid systems. An economic analysis found that major cost reductions would need to be achieved for such systems to compete with conventional energy storage devices.     

Multi-module parallel small battery energy storage system

This paper presents a multi-module parallel single-phase battery energy storage system (BESS). The single module BESS to be paralleled consists of only a full-bridge power converter. When the utility is in normal condition, the BESS serves as a power conditioner as well as an active power filter. It can be arranged to charge the battery bank or to share daily peak load. In any case, the current supplied by the electric utility can be maintained sinusoidal and almost in phase with voltage. When a utility power failure occurs, the BESS functions as an inverter to supply uninterruptible power to the load. With the good current sharing feature possessed by this BESS, a central power distribution control scheme with smooth current transfer characteristic is proposed to control the parallel operation of the multi-module BESS. The current sharing of each BESS module can be programmed according to its rating and the load condition. Designs of the power circuit and the central power distribution control scheme are described detailedly in this paper. The effectiveness and performance of the proposed parallel BESS are demonstrated by some experimental results     

Economic models for battery energy storage: improvements forexisting methods

While the technology required to produce a viable battery energy storage system exists, the economic feasibility of building these systems requires justification. A generalized decision diagram was developed to ensure that all of the economic factors were considered and properly related for the customer side of the meter. Two economic models that had consistently given differing results were compared. One was the McKinney model developed at the University of Missouri at Rolla in 1987; the second was the SYSPLAN model developed by Battelle. Four specific cases were evaluated and compared. Differences were resolved on a point-by-point basis with reference to the current economic environment. The economic model was upgraded to include the best of both models based on the resolution of these differences. The upgrades were implemented as modifications to the original SYSPLAN (1986 version) to preserve user friendliness. The modified version is the result of an investigation into current standards and practices in engineering economics as well as power distribution engineering. Therefore, more accurate results are returned to the user. Comparisons have shown that this program generally returns values between the more conservative McKinney model and the more optimistic SYSPLAN model. However, the results do not follow a linear relationship between the two extremes