风电/制氢/燃料电池/超级电容器混合系统控制策略

风能的波动性及间歇性致使传统风力机出力不可控,即出力曲线与负荷调度曲线不一致。本文构造了一种风电/制氢/燃料电池/超级电容器耦合于直流母线的结构。针对风电/制氢/燃料电池/超级电容器混合系统10种运行模式,提出了一种能量管理策略,确保在各个控制单元的作用下,能量协调流动于混合系统各子单元之间。此能量管理策略不仅使混合系统出力可控,而且提高了风能利用率,平抑了直流母线电压波动,平滑了上网功率。PSCAD/EMTDC仿真结果验证了风电/制氢/燃料电池/超级电容器混合系统控制策略的有效性。     

Power and energy management of grid/PEMFC/battery/supercapacitor hybrid power sources for UPS applications

This paper presents a hybrid power and energy source supplied by a proton exchange membrane fuel cell (PEMFC) as the main power source in an uninterruptible power supply (UPS) system. To prevent the PEMFC from fuel starvation and degradation and realize their seamless linking in the hybrid UPS system, the power and energy are balanced by the battery and/or supercapacitor (SC) as two alternative auxiliary power sources. Based on the modeling and sizing of hybrid power and energy components, the power and energy management strategies and efficiency measurements of four operating modes in UPS system are proposed. To evaluate the proposed strategies, an experimental setup is implemented by a data acquisition system, a PEMFC generating system, and a UPS system including AC/DC rectifier, DC/AC inverter, DC/DC converter, AC/DC recharger and its intelligent control unit. Experimental results with the characteristics of a 300 W self-humidified air-breathing of PEMFC, 3-cell 12 V/5 Ah of batteries, and two 16-cell 120 F/2.7 V of SCs in parallel corroborate the excellent management strategies in the four operating modes of UPS system, which provides the basis for the optimal design of the UPS system with hybrid PEMFC/battery/SC power sources.     

Development of an efficient utility interactive combined wind/photovoltaic/fuel cell power system with MPPT and DC bus voltage regulation

In this paper, development and simulation of an efficient small-scale centralized dc-bus grid connected hybrid wind/photovoltaic/fuel cell for supplying power to a low voltage distribution system are presented. The hybrid system consists of wind and photovoltaic as a primary power system. A fuel cell is added as a secondary system to ensure continuous power supply and to take care of the intermittent nature of wind and photovoltaic. The objective of this study is to design and control a hybrid system that guarantees the energy continuity. A simple control method is applied to the proposed configuration to simultaneously achieve three desired goals: to extract maximum power from each hybrid power system component; to guarantee dc bus voltage regulation at the input of the inverter; and to transfer the total produced power to the grid at unity power factor, while fulfilling all necessary interconnection requirements. The power fluctuation of the proposed hybrid system has been reduced as compared to that of each individual system and it has been completely suppressed using the FC system. The simulation results indicate that the dc-dc converters are very effective in tracking the maximum power of the wind and photovoltaic sources, the fuel cell controller responds efficiently to the deficit power demands. With both wind and photovoltaic systems operating at their rated capacity, the system can generate power as high as 2 kW and the fuel cell does not need to be utilized in such cases.     

孤岛风柴蓄复合发电功率粒子群优化分配研究

利用可再生能源发电是海岛解决用电和吃水难问题的有效途径之一。对南海某海岛的风力资源和用电负荷分析后,提出采用风柴蓄复合发电蓄电为海岛提供电力,多余电力用于海水淡化的方案。在风柴蓄复合发电的功率设计中往往依靠经验,提出应用改进的粒子群优化方法对孤岛风柴蓄复合发电的风力发电机组台数、柴油机台数和蓄电池容量进行优化设计,优化中采用度电成本最小作为目标,最小失电率作为约束条件,能量调度按照首先应用可再生能源发电,其次是蓄电池电量,最后调用柴油机发电的策略。结果显示,改进优化方法的效率比基本的粒子群优化算法稍低,但是可以得到更加优化的结果。进一步分析了当柴油价格、负荷、蓄电池价格和风力发电机成本变化后,优化出新的风力发电机、柴油发电机和蓄电池配置,分析了优化配置变化的原因。研究可以为在孤立海岛采用风柴蓄复合发电蓄电的设计提供参考。     

An operating method using prediction of photovoltaic power for a photovoltaic–diesel hybrid power generation system

This paper describes a novel operating method using prediction of photovoltaic (PV) power for a photovoltaic–diesel hybrid power generation system. The system is composed of a PV array, a storage battery, a bidirectional inverter, and a diesel engine generator (DG). The proposed method enables the system to save fuel consumption by using PV energy effectively, reducing charge and discharge energy of the storage battery, and avoiding low‐load operation of the DG. The PV power is simply predicted from a theoretical equation of solar radiation and the observed PV energy for a constant time before the prediction. The fuel consumption of the proposed method is compared with that of other methods by a simulation based on measurement data of the PV power at an actual PV generation system for 1 year. The simulation results indicate that the amount of fuel consumption of the proposed method is smaller than that of any other methods, and is close to that of the ideal operation of the DG. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(3): 8–18, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20116     

Energy management optimization of a hybrid power production unit based renewable energies

Hybrid power production units seem to be an interesting alternative for supplying isolated sites. This study proposes a new supervision strategy in order to ensure an optimized energy management of the hybrid system. The considered hybrid unit includes a wind generator (WG), a fuel cell (FC), an electrolyzer (EL) and a supercapacitor (SC). An overall power supervision approach was designed to guarantee the power flow management between the energy sources and the storage elements. The aim of the control system is to provide a permanent supply to the isolated site by adapting production to consumption according to the storage level. A mathematical analysis of the hybrid system using models implemented in Matlab/Simulink software was developed. Simulation results illustrate the performance of the control strategy for an optimal management of the hybrid power production unit under different scenarios of power generation and load demand.     

Study on stand-alone power supply options for an isolated community

There are three inhabited islands in Hong Kong beyond the reach of the utility grid. Currently they are powered by diesel generators with fuel supplied by barge. To reduce dependence on diesel and improve power supply quality, the government is planning to explore locally available renewable energy for power generation on the islands. In this study, several power supply options such as renewable energy and diesel power generation were considered for one remotely located community. A techno-economic analysis and a detailed hourly simulation were performed to find an optimal autonomous system configuration. The results were evaluated in terms of power supply quality, life cycle cost, payback time, and greenhouse gas emission. The effects of load variation on system configuration and cost were also examined. The feasibility study demonstrates that the hybrid solar–wind–diesel–battery system could provide the optimal techno-economic performance, and this scenario was discussed with elaborate analysis. The study also shows that the energy dispatch strategy is very important for a system consisting of two dispatchable sources. Compared to a fully renewable energy system, the introduction of a back-up diesel generator in the hybrid energy system can be a more viable option, even though high diesel fuel cost is needed.     

混合动力系统的控制系统设计与仿真

设计了一种新颖的质子交换膜燃料电池/蓄电池的混合动力模型,该混合动力模型以锂电池为主,燃料电池为辅。该系统可以实时监测负载电流,假设并实现了在负载电流不大于10 A时,由锂电池单独工作;当负载电流大于10 A时,燃料电池和锂电池共同工作,提供功率。在Simulink平台上建模并验证了所设计的混合动力系统的能量管理策略的可行性。     

家用混合发电系统的能量优化控制策略

家庭负载频繁出现瞬间的峰值功率需求,由燃料电池/蓄电池组成的混合发电系统是最清洁和高效的发电方式之一.燃料电池仅满足基本负载,由蓄电池放电以满足瞬间的峰值功率需求.研究了一个60 kW家用混合发电系统,该系统由质子交换膜燃料电池(PEMFC)和阀控铅酸蓄电池组成,设计为10个家庭同时供电.在保证系统可靠性和持久性的同时,为了提高整个混合发电系统的工作效率和燃料经济性,在系统仿真和分析的基础上详细描述了一种基于规则的能量优化控制策略.仿真实验结果表明,与燃料电池单独供电相比,60 kW混合发电系统通过优化2种能源之间的功率分配,能够在响应负载的同时提高整个发电系统的工作效率和燃料经济性.     

Intelligent power management strategy of hybrid distributed generation system

This paper describes a novel control strategy for active power flow in a hybrid fuel cell/battery distributed generation system. The method introduces an on-line power management by a hierarchical hybrid controller between dual energy sources that consist of a battery bank and a solid oxide fuel cell (SOFC). The proposed method includes an advance supervisory controller in the first layer which captures all of the possible operation modes. This layer has been developed by Stateflow toolbox and prepares a proper supervisory environment for this complex structure. In the second layer, an advanced fuzzy controller has been developed for power splitting between battery and fuel cell. With regards to the operation modes, the upper layer makes decision to choose the switching chain rules and corresponding controller in the second layer. Finally in the third layer, there are local controllers to regulate the set points of each subsystems to reach the best performance and acceptable operation indexes. Simulation results of a test system illustrate improvement in the operation efficiency of the hybrid system and the battery state of charge has been maintained at a reasonable level.     

光伏/燃料电池联合发电系统的建模和性能分析

当前的环境污染和能源短缺使得清洁且资源丰富的光伏发电倍受关注, 太阳能的随机和间断特性使得独立式光伏系统需要配置相应能源存储设备才能实现电力的连续供应。本文提出一种光伏/燃料电池联合发电系统, 建立了包括光伏模板、燃料电池、电解池、压缩机、氢气罐和蓄电池的系统元件模型, 设计了能源管理策略协调联合系统的能源分配,对系统实现全年能源供需平衡的性能进行了分析。仿真结果表明该联合发电系统可以满足用户全年的负载需求,是传统供电方式的重要补充。     

Cost reduction of a hybrid energy storagesystem considering correlation betweenwind and PV power

A hybrid energy storage system (HESS) plays an important role in balancing the cost with the performance in terms of stabilizing the fluctuant power of wind farms and photovoltaic (PV) stations. To further bring down the cost and actually implement the dispatchability of wind/PV plants, there is a need to penetrate into the major factors that contribute to the cost of the any HESS. This paper first discusses hybrid energy storage systems, as well as chemical properties in different medium, deeming the ramp rate as one of the determinants that must be observed in the cost calculation. Then, a mathematical tool, Copula, is explained in details for the purpose of unscrambling the dependences between the power of wind and PV plants. To lower the cost, the basic rule for allocation of buffered power is also put forward, with the minimum energy capacities of the battery ESS(BESS) and the supercapacitor ESS(SC-ESS) simultaneously determined by integration. And the paper introduces the probability method to analyze how power and energy is compensated in certain confidence level. After that, two definitions of coefficients are set up, separately describing energy storage status and wind curtailment level. Finally, the paper gives a numerical example stemmed from real data acquired in wind farms and PV stations in Belgium. The conclusion presents that the cost of a hybrid energy storage system is greatly affected by ramp-rate and dependence between the power of wind farms and photovoltaic stations, in which dependence can easily be determined by Copulas.     

复合式燃料电池供电系统

提出了一种新型的复合式燃料电池供电系统.它是由燃料电池、蓄电池、单向变换器、双向变换器和逆变器构成.根据燃料电池的特性,提出了复合式全桥三电平LLC谐振变换器和三电平Buck/Boost双向变换器分别作为系统的单向和双向变换器运用于系统中.该结构可以优化能量管理,在冷启动过程由蓄电池向负载供电,而燃料电池不供电,系统易于冷启动;在负载突变时,可由蓄电池提供或吸收动态能量,使得系统具有很好的动态特性;在过载时,燃料电池仅提供额定功率,而过载部分能量由蓄电池提供,燃料电池的功率等级只需按照系统额定功率进行配置,从而降低整个系统的成本.最后在实验室中完成了一个1kW复合式燃料电池供电系统,并对系统进行实验研究,以验证理论分析的正确性.     

分布式新能源发电中储能系统能量管理

本文对蓄电池和超级电容组成储能系统的能量管理进行研究,根据两种储能装置的特点和剩余容量以及分布式发电系统的状态,将储能系统的工作模式分类,并对每种工作模式采用不同的控制策略,发挥蓄电池和超级电容自身的优点,保证系统内部的功率平衡,减小风能、太阳能等新能源发电系统功率波动对外部电网的冲击,并实现孤岛运行。最后通过分布式新能源发电系统仿真和实验平台对控制策略进行了验证。     

Cost reduction of a hybrid energy storage system considering correlation between wind and PV power

A hybrid energy storage system (HESS) plays an important role in balancing the cost with the performance in terms of stabilizing the fluctuant power of wind farms and photovoltaic (PV) stations. This paper first discusses hybrid energy storage systems, as well as chemical properties in different medium, deeming the ramp rate as one of the determinants that must be observed in the cost calculation. Then, a mathematical tool, Copula, is explained in details for the purpose of unscrambling the dependences between the power of wind and PV plants. To lower the cost, the basic rule for allocation of buffered power is also put forward, with the minimum energy capacities of the battery ESS(BESS) and the supercapacitor ESS(SC-ESS) simultaneously determined by integration. And the paper introduces the probability method to analyze how power and energy is compensated in certain confidence level. After that, two definitions of coefficients are set up, separately describing energy storage status and wind curtailment level. Finally, the paper gives a numerical example stemmed from real data acquired in wind farms and PV stations in Belgium. The conclusion presents the fact that the cost of a HESS varies not only with the ramp rate of its BESS, but also inevitably with the dependences between the power of wind and PV plants, which means both are indispensable considerations.     

混合能源直流微电网能源优化管控策略研究

混合能源直流微电网在快速跟踪负载方面具有较大优势,弥补了固体氧化物燃料电池(solidoxidefuelcell,SOFC)直流微电网功率跟踪缓慢的问题。现有能源管控策略重点关注能源分配,对系统效率、运行安全性和燃料亏空方面缺乏相关研究和成熟策略。为此,提出了一种混合能源直流微型电网能源优化管控策略。首先,搭建了混合SOFC直流微电网模型。其次,采用最优操作点(optimal operating points, OOPs)实现最大效率,然后采用平均电流控制模式保证稳定的电力供应。最后,设计了基于SOFC电流的时滞控制算法来避免燃料亏空。实验结果表明,所提出的能源优化管控策略具有时间响应迅速、输出效率高和热特性良好等优势。     

Economic Evaluation of Power System Flexibility by Commercial Air Conditioner Control with Large Penetration of Photovoltaic Generation

High penetration of intermittent renewable energy such as photovoltaic (PV) and wind power could cause shortage of power system flexibility. Demand response is expected to help supply ancillary service instead of the conventional power plant. Commercial air conditioners are a promising responsive load for demand response because they account for a large proportion of power consumption in the power system. We calculate a system operation cost and hourly operation pattern of each power plant by using the optimal power generation model considering flexibility supply from controlling commercial air conditioner. We obtained the following results as an effect of commercial air conditioner control. (1) The power generation of oil fired power plants decreases at peak time and annual fuel cost of oil fired plant is reduced by approximately 30% at most in Kanto area. (2) The percentage of rated operation mode of LNG combined cycle plants increases. (3) Curtailed energy rate of PV decreases because a power storage amount by pumped hydropower generation increases. (4) Required battery capacity to reduce PV curtailed amount decreased by combining battery energy storage system in case of high penetration of PV.     

Characteristics of photovoltaic/fuel cell power hybrid system. (Effect on electrical load form factors)

The photovoltaic power system has a great future as a clean-energy alternative to fossil fuel which has many environmental problems such as gas exhaustion or air pollution. Sunlight, a source of energy for the system, is influenced greatly by weather conditions, seasons and times of day. Therefore it cannot supply constant electric power. The photovoltaic/fuel cell power hybrid system is assumed. It combines PV array, hydrogen generator, storage tank and fuel cells by using hydrogen. This system can supply constant electric power to the electric load in a solitary island separated from a commercial electric network. The possibility of this system is examined by computer simulation. Input data include the global irradiance on inclined plane and temperature of HASP data of Tokyo, ten kinds of electrical load forms with 400 MWh electric power a year, and conversion efficiencies of each subsystem. As a result of simulation, it was revealed that the area of PV array with 8170 m² and the volume of hydrogen tank from 22 × 10³ to 30 × 10³ kl are necessary.     

基于碱性电解槽宽功率适应模型的风光氢热虚拟电厂 容量配置与调度优化

为提高能源利用效率,降低碳排放水平,改善虚拟电厂运行效益,构建了基于碱性电解槽宽功率适应模型的风光氢热虚拟电厂(Virtual Power Plant, VPP)模型。将制氢电解槽、氢燃料电池、储氢罐构成氢能系统,代替传统虚拟电厂中的蓄电池,并提出碱性电解槽宽功率适应模型,提高电解槽在不同输入功率条件下的适应性。利用氢能系统运行时产生热量对系统负荷实行热电联供,并将电解槽产生氧气出售。在此基础上,使用改进多路无网格光线寻优算法对各设备出力调度与设备容量配置进行优化。仿真结果表明,该算法在计算精度和速度上有一定提高。基于碱性电解槽宽功率适应模型的风光氢热VPP,在降低系统运行成本的同时可以有效应对风、光出力波动,提高风、光消纳水平,减少碳排放。     

Online energy management strategy of a hybrid fuel cell/battery/ultracapacitor vehicular power system

A hybrid power system based on a fuel cell (FC) and an energy storage system appears to be very promising for satisfying the high energy and high power requirements of automotive applications in which the power demand is impulsive rather than constant. This paper deals with the use of a hybrid energy storage system with the battery (BAT)/ultracapacitor (UC) as ancillary power source in FC electric vehicles. The energy management strategy (EMS) is one of the most important issues for the efficiency and performance of such systems. The designed EMS uses a splitting method, allowing a natural frequency decomposition of the power demands. It takes into account the slow dynamics of FC and the state of charge of the UC and BAT. A simulation is conducted using MATLAB/SIMULINK software in order to verify the effectiveness of the proposed control strategy. It confirms the performance of the control method and also demonstrates the robustness and stability of the control strategy with good tracking response (transient performance), low overshoot, zero steady‐state error, and control flexibility during a power demand cycle. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.