A power allocation strategy of a hybrid energy storage system for a PV grid-connected system

针对光伏并网系统中光伏微电源出力的波动性和间歇性,将蓄电池和超级电容器构成的混合储能系统HESS（hybrid energy storage system）应用到光伏并网系统中可以实现光伏功率平滑、能量平衡以及提高并网电能质量。在同时考虑蓄电池的功率上限和超级电容的荷电状态（SOC）的情况下,对混合储能系统提出了基于超级电容SOC的功率分配策略;该策略以超级电容的SOC和功率分配单元的输出功率作为参考值,对混合储能系统充放电过程进行设计。超级电容和蓄电池以Bi-direction DC/DC变换器与500 V直流母线连接,其中超级电容通过双闭环控制策略对直流母线电压进行控制。仿真结果表明,所提功率分配策略能对混合储能系统功率合理分配,而且实现了单位功率因数并网,稳定了直流母线电压。     

面向配电网优化的混合储能系统控制策略

文章提出一种面向配电网优化运行的混合储能系统控制策略。首先建立光伏-混合储能系统柔性并网模型,针对配电网"源-网"经济运行和节点电压优化目标,提出光伏-混合储能系统参与配电网优化运行策略,获得混合储能最优目标功率;然后根据荷电状态及其充放电状态,提出混合储能多目标分频和内部能量协调控制策略,合理分配蓄电池和超级电容器的充放电功率。仿真结果表明,该策略不仅可以有效实现配电网经济运行和节点电压越限治理,而且能够充分发挥不同储能介质的技术特性,延长混合储能系统的运行寿命。     

基于混合储能的并网光伏发电系统功率控制研究

针对并网光伏发电系统输出功率的波动,提出利用混合储能系统对功率进行平抑.介绍了光伏最大功率跟踪和并网逆变的控制,为实现发电和并网功率的匹配,考虑蓄电池和超级电容器各自特性的优势,对混合储能系统提出了三级式功率分配策略;通过设计相应的控制方法和以功率分配单元的输出功率作为参考值,混合储能系统控制变换器进行合理充放电.混合储能系统不仅保证了并网功率按计划运行,而且稳定了直流母线电压、满足了随机负荷供电.通过仿真验证,三级式功率分配策略有效,控制方法可行.     

考虑超级电容荷电状态的光伏发电系统功率控制研究

针对光伏出力的波动性和间歇性,文章将蓄电池和超级电容器相结合的混合储能系统HESS(Hybrid Energy Storage System)应用到光伏并网系统,实现了光伏系统的功率平滑,平衡能量,提高并网电能质量。同时考虑到低通滤波法在进行功率分配时存在滤波时间常数难以计算的问题,就蓄电池与超级电容提出一种由超级电容荷电状态(SOC)来反馈二者功率分配的控制策略;该策略以超级电容的SOC和功率分配单元的输出功率作为参考值,对混合储能系统充放电过程进行设计。仿真结果表明:与低通滤波法相比,文章所提功率分配控制策略延长了蓄电池的使用年限,防止了超级电容器的过充、过放,而且实现了单位功率因数并网。     

光储微网的储能优化配置与技术经济分析

在储能系统和光伏发电相结合的统筹规划中,电池储能投资成本、光伏装机容量、光伏并网价格以及热电联产(CHP)的采用对电池储能的容量配置和电池充放电策略具有显著影响。基于分时电价下的光伏储能系统,将电池储能的容量和功率的配置转化为根据电价时段划分的约束优化问题。以某工业园区为研究对象,建立光伏-储能系统功率流模型,优化计算得到经济效益最优化的电池容量和功率配置结果及电池充放电策略。基于内部收益率、光伏自我消纳率等指标,根据光伏上网价格和电网谷段电价的关系划分场景,通过光伏发电容量和电池价格的变化探究光伏-储能系统中电池储能的容量配置、经济效益的变化规律和热电联产对系统的影响。     

独立光伏供电系统中多储能单元协调控制策略的研究

文章提出了一种由超级电容器和多个蓄电池储能单元组成的混合储能系统,并将该储能系统应用于独立光伏供电系统。其中,多个蓄电池储能单元能够增大混合储能系统的容量,并提高供电系统的可靠性。由于不同的蓄电池储能单元的荷电状态存在差异,因此,提出了一种改进SOC下垂控制方法,并利用该控制方法实现了不同蓄电池储能单元传输功率的优化分配和SOC的动态均衡,优化了蓄电池储能单元的能量传输过程。超级电容器可以补偿光伏系统传输功率缺额的高频部分,减少蓄电池储能单元充、放电的次数,维持直流母线电压的稳定。文章通过仿真模拟,验证了所提出的控制策略能够优化各储能单元的运行状态,并有效地维持了光伏系统传输功率的平衡和直流母线电压的稳定。     

混合储能提高风出力预测精度研究

风气象信息精细化程度不够造成风电场风出力预测精度低,给电网调度增加了难度,采用储能装置可提高预测精度,但是合理又经济地配置储能容量较困难。文章提出在风电场中配置蓄电池和超级电容器混合储能系统,提高风电场日前预报精度;通过高通滤波器得到误差变化较快的成分,由超级电容器来弥补;由蓄电池来弥补剩余变化较慢的误差成分。综合考虑这些误差变化特点及储能充放电功率发生概率特点,合理选取储能额定容量,并且分别搭建了超级电容器和蓄电池储能系统模糊控制规则库,根据各自荷电状态SOC优化分配混合储能充放电功率。最后对新疆某风电场并入混合储能进行了仿真分析,结果表明:采用模糊控制策略的混合储能系统能够更显著有效地提高风出力短期预测精度。     

基于PSoC的太阳能MPPT系统控制器设计

为了实现对光伏发电照明系统能量的优化管理,提高能量利用效率,设计了基于可编程片上系统(PSoC) CY8C29466的光伏能量管理控制系统.系统对太阳能电池的功率输出采取了最大功率点跟踪控制(MPPT),一定程度上提高了光伏系统的输出效率.在蓄电池充放电过程中,采取了断开回路、连接负载的检测方法,实现了对蓄电池容量的准确检测,有效的防止了蓄电池过充、过放的发生,延长了其使用寿命.系统后期测试数据表明,基于PSoC的光伏能量管理系统可以对太阳能电池的输出和蓄电池的充放电进行有效控制,具有广泛的应用前景.     

含小水电集群的互补微网混合储能容量配置

针对功率型和能量型储能装置的特点,提出了一种由小水电群等多种分布式能源构成的微电网混合储能容量最优配置方法。基于风、光、水年出力特性曲线与全网年负荷曲线,以购置成本、运行与处理成本为目标,系统储能容量、微网瞬时功率、系统最小功率、蓄电池放电深度以及超级电容充放电电流与电压等条件为约束,采用自适应遗传算法对目标函数进行求解,得到混合储能系统中蓄电池和超级电容的最优容量。结果表明,较之传统的蓄电池储能系统,混合储能系统可以大大减小购置与运行成本。     

一种蓄电池储能系统容量优化配置方法

蓄电池储能单元是独立可再生能源发电系统中必不可少的环节,通过其充放电控制能够满足发电功率与复合之间的实时匹配。蓄电池储能系统成本比较高,在进行容量配置时通常需要综合考虑系统的指标要求与成本关系,从而尽可能在满足工作要求的情况下降低储能单元的成本。提出了一种蓄电池储能系统经济性模型,通过给定工作指标的要求利用遗传算法进行储能系统容量优化配置。     

Dynamic modeling and sizing optimization of stand-alone photovoltaic power systems using hybrid energy storage technology

Economic and environmental concerns over fossil fuels encourage the development of photovoltaic (PV) energy systems. Due to the intermittent nature of solar energy, energy storage is needed in a stand-alone PV system for the purpose of ensuring continuous power flow. Three stand-alone photovoltaic power systems using different energy storage technologies are studied in this paper. Key components including PV modules, fuel cells, electrolyzers, compressors, hydrogen tanks and batteries are modeled in a clear way so as to facilitate the evaluation of the power systems. Based on energy storage technology, a method of ascertaining minimal system configuration is designed to perform the sizing optimization and reveal the correlations between the system cost and the system efficiency. The three hybrid power systems, i.e., photovoltaic/battery (PV/Battery) system, photovoltaic/fuel cell (PV/FC) system, and photovoltaic/fuel cell/battery (PV/FC/Battery) system, are optimized, analyzed and compared. The obtained results indicate that maximizing the system efficiency while minimizing system cost is a multi-objective optimization problem. As a trade-off solution to the problem, the proposed PV/FC/Battery hybrid system is found to be the configuration with lower cost, higher efficiency and less PV modules as compared with either single storage system.     

Dynamic modeling of a photovoltaic hydrogen fuel cell hybrid system

The objective of this paper is to mathematically model a stand-alone renewable power system, referred to as “Photovoltaic–Fuel Cell (PVFC) hybrid system”, which maximizes the use of a renewable energy source. It comprises a photovoltaic generator (PV), a water electrolyzer, a hydrogen tank, and a proton exchange membrane (PEM) fuel cell generator. A multi-domain simulation platform Simplorer is employed to model the PVFC hybrid systems. Electrical power from the PV generator meets the user loads when there is sufficient solar radiation. The excess power from the PV generator is then used for water electrolysis to produce hydrogen. The fuel cell generator works as a backup generator to supplement the load demands when the PV energy is deficient during a period of low solar radiation, which keeps the system's reliability at the same level as for the conventional system. Case studies using the present model have shown that the present hybrid system has successfully tracked the daily power consumption in a typical family. It also verifies the effectiveness of the proposed management approach for operation of a stand-alone hybrid system, which is essential for determining a control strategy to ensure efficient and reliable operation of each part of the hybrid system. The present model scheme can be helpful in the design and performance analysis of a complex hybrid-power system prior to practical realization.     

Performance comparison investigation on solar photovoltaic-thermoelectric generation and solar photovoltaic-thermoelectric cooling hybrid systems under different conditions

The performance of solar photovoltaic-thermoelectric generation hybrid system (PV-TGS) and solar photovoltaic-thermoelectric cooling hybrid system (PV-TCS) under different conditions were theoretically analysed and compared. To test the practicality of these two hybrid systems, the performance of stand-alone PV system was also studied. The results show that PV-TGS and PV-TCS in most cases will result in the system with a better performance than stand-alone PV system. The advantage of PV-TGS is emphasised in total output power and conversion efficiency which is even poorer in PV-TCS than that in stand-alone PV system at the ambient wind speed u_w being below 3 m/s. However, PV-TCS has obvious advantage on lowering the temperature of PV cell. There is an obvious increase in tendency on the performance of PV-TGS and PV-TCS when the cooling capacity of two hybrid systems varies from around 0.06 to 0.3?W/K. And it is also proved that not just a-Si in PV-TGS can produce a better performance than the stand-alone PV system alone at most cases.     

超级电容器-蓄电池应用于独立光伏系统的储能设计

建立了混合储能系统的数学模型,对模型系统进行了稳定性分析,从应用角度出发,设计了一套超级电容器-蓄电池混合储能装置应用在独立光伏系统,使用PSPICE软件仿真分析了系统的运行特性,结果表明系统在光伏输入功率大幅波动以及负载突变时具有很好的稳定性,可为超级电容器应用于可再生能源发电和电能质量改善等领域提供较好的参考。     

Generation unit sizing and cost analysis for stand-alone wind,photovoltaic, and hybrid wind/PV systems

This paper presents the results of investigations on the application of wind, photovoltaic (PV), and hybrid wind/PV power generating systems for utilization as stand-alone systems. A simple numerical algorithm has been developed for generation unit sizing. It has been used to determine the optimum generation capacity and storage needed for a stand-alone, wind, PV, and hybrid wind/PV system for an experimental site in a remote area in Montana with a typical residential load. Generation and storage units for each system are properly sized in order to meet the annual load and minimize the total annual cost to the customer. In addition, an economic analysis has been performed for the above three scenarios and is used to justify the use of renewable energy versus constructing a line extension from the nearest existing power line to supply the load with conventional power. Annual average hourly values for load, wind speed, and insolation have been used     

Operation strategy of residential centralized photovoltaic system in remote areas

Photovoltaic (PV) systems have found fairly wide application in remote isolated area. However, each individual PV system usually supplies energy only to one consumer. In such a case we have several consumers that each one of them uses a stand-alone PV system. This situation would expose such stand-alone systems to transient excessive loads larger than the power generated by the PVs, and then the battery is bound to discharge even during the day. For overcoming this problem, we suggest an autonomous centralized PV system, comprising one battery bank and plural subsystems connected to each other. From solar radiation data and load profiles, the performance of the PV centralized system is simulated by using a time step scheme. The advantages of this system are found to be the large charging rate of power, high efficiency, and low cost compared with conventional individual PV systems and hybrid systems. In addition, the economic study shows that the life cycle cost and the price of kilowatt hour generated in the centralized system is lower than that for the individual systems.     

Review and comparison study of hybrid diesel/solar/hydro/fuel cell energy schemes for a rural ICT Telecenter

In this paper, the rural electrification study of an ICT Telecenter in particular reference to the Kelabit Highland of Sarawak is presented. The use of diesel generator and its associated environmental implications is first discussed. The cost-effectiveness of the present solar PV system and the solar/hydro schemes for rural electrification of the rural ICT are evaluated employing the HOMER simulation software, considering sustainability factors such as system efficiency, weather, fuel costs, operating and maintaining costs. Subsequently, simple novel Hybrid Energy Performance Equations and the associated Energy Performance Curves are derived and introduced, respectively, which provide a visualization model, simplifying hybrid system analysis. Results obtained in this study have shown that combined power schemes is more sustainable in terms of supplying electricity to the Telecenter compared to a stand-alone PV system due to prolong cloudy and dense haze periods. The hybrid systems can have efficiency range of ∼15%–75% compared to PV stand-alone of only ∼10%, indicating hybrid systems are more reliable and sustainable – in minimizing both energy losses and excess energy.     

Frequency deviation control by coordination control of FC and double-layer capacitor in an autonomous hybrid renewable energy power generation system

In this paper, a novel control strategy for frequency control in stand-alone application based on coordination control of fuel cells (FCs) and double-layer capacitor (DLC) bank in an autonomous hybrid renewable energy power generation system is implemented. The proposed renewable energy power generation subsystems include wind turbine generator (WTG), photovoltaic system (PV), FC system and DLC bank as energy storage system. The system performance under different condition has been verified by using real weather data. Simulation results demonstrate the validity of proposed studied hybrid power generation system feeding isolated loads in power frequency balance condition.     

Assessment of economic viability for PV/wind/diesel hybrid energy system in southern Peninsular Malaysia

This paper analyzed the potential implementation of hybrid photovoltaic (PV)/wind turbine/diesel system in southern city of Malaysia, Johor Bahru. HOMER (hybrid optimization model for electric renewable) simulation software was used to determine the technical feasibility of the system and to perform the economical analysis of the system. There were seven different system configurations, namely stand-alone diesel system, hybrid PV–diesel system with and without battery storage element, hybrid wind–diesel system with and without battery storageelement, PV–wind–diesel system with and without storage element, will be studied and analyzed. The simulations will be focused on the net present costs, cost of energy, excess electricity produced and the reduction of CO₂ emission for the given hybrid configurations. At the end of this paper, PV–diesel system with battery storage element, PV–wind–diesel system with battery storage element and the stand-alone diesel system were analyzed based on high price of diesel.     

DESIGN OF HYBRID-PHOTOVOLTAIC POWER GENERATOR, WITH OPTIMIZATION OF ENERGY MANAGEMENT

A methodology is developed for calculating the correct size of a photovoltaic (PV)-hybrid system and for optimizing its management. The power for the hybrid system comes from PV panels and an engine-generator – that is, a gasoline or diesel engine driving an electrical generator. The combined system is a stand-alone or autonomous system, in the sense that no third energy source is brought in to meet the load. Two parameters were used to characterize the role of the engine-generator: denoted SDM and SAR, they are, respectively, the battery charge threshold at which it is started up, and the storage capacity threshold at which it is stopped, both expressed as a percentage of the nominal battery storage capacity. The methodology developed is applied to designing a PV-hybrid system operating in Corsica, as a case study. Various sizing configurations were simulated, and the optimal configuration that meets the autonomy constraint (no loss of load) was determined, by minimizing of the energy cost. The influence of the battery storage capacity on the solar contribution is also studied. The smallest energy cost per kWh was obtained for a system characterized by an SDM=30% and an SAR=70%. A study on the effects of component lifetimes on the economics of PV-hybrid and PV stand-alone systems has shown that battery size can be reduced by a factor of two in PV-hybrid systems, as compared to PV stand-alone systems.