基于变效率压气机的AA-CAES变工况性能分析

先进绝热压缩空气储能系统(advanced adiabatic compressed air energy storage system,AA-CAES)是一种清洁、环保的大规模储能技术,能够为可再生能源并网及电网调峰提供新的解决方案。为了深入研究压气机模型对变工况下AA-CAES系统运行性能的影响,本文在传统模型的基础上添加了压气机效率模型。求解系统模型发现:相对于储气室最高压比,换热器效能对储能效率的影响较大,换热器效能每提高0.05,储能效率平均提高2.9%;随着储气室最高压比的上升,储能密度近似呈线性增加;AA-CAES系统在储能阶段,稳定运行的前两级压气机功率保持不变,非稳定运行的第3级压气机功率随储气室压比的升高而逐渐增大,储能阶段结束时第3级压气机耗功最多。     

Distensible air accumulators as a means of adiabatic underwater compressed air energy storage

In the near future, the electricity industry is likely to face historically significant changes. The onset of distributed generation, micro and smart grids will change the entire structured industry. An influx of intermittent renewable generators will make traditional grid balancing notably more difficult. The novel concept of underwater compressed air energy storage is a potentially promising solution that may be used to meet these challenges, especially during the current period of electrical infrastructure renewal and modernisation. Early results from a Lake Ontario Pilot Study point to the potential viability of the concept.     

Dynamic simulation of air storage–based gas turbine plants

Cavern storage is a proven energy storage technology, capable of storing energy in the form of compressed air inside a cavern. The Huntorf plant and the Alabama plants use this technology to store electrical energy during the off‐peak load hours by compressing the air inside a cavern and then using this compressed air during gas turbine operation to generate electricity during peak load demand hours. The advantage of doing this is that it increases the efficiency of gas turbine operation while meeting the grid generation and the load balance. The operation of a typical compressed air energy storage (CAES)–based gas turbine plant involves the operation of several components, including the compressor, the cavern storage, the combustor, the turbine, and so on. The dynamics of the plant as a whole depends on the performance of the individual components. The focus of this article is to develop a Simulink‐based models for each of the individual components, which can then be assembled appropriately to design an entire CAES plant. As an illustration, a case study for the Huntorf CAES plant is presented with the developed models. A typical daily operation of the Huntorf plant is simulated and compared with the reported Huntorf plant data. The model accurately captures the reported dynamics of the cavern storage. In addition, the reported quantities like the compressor power consumption, the turbine power generation, and the temperature at different junctions of the CAES plant match well with the simulated results. Copyright © 2011 John Wiley & Sons, Ltd.     

新型变压比压缩空气储能系统及其运行方式

为了提高压缩空气储能(CAES)系统的效率,提出了新型变压比压缩空气储能系统。该系统基于定容储气装置及传统定压比压缩方式的特性,通过阀门调节来改变储能过程中压缩级组的串并联运行方式实现。通过分析不同压缩级数下可行的变压比运行方式,建立变压比压缩空气储能系统的仿真模型,从仿真得出的变压比储能系统的储能时间、压缩功耗和系统的充放电效率等方面,与传统的定压比压缩空气储能系统进行比较。结果表明,变压比压缩空气储能系统不仅减少了储能过程中压缩机组的功耗、缩短了储能时间,而且提高了整个系统的充放电效率。     

Design of a Centrifugal Compressor with Low Solidity Vaned Diffuser (LSVD) for Large-Scale Compressed Air Energy Storage (CAES)

Compressed Air Energy Storage(CAES) has tremendous promotional value in the intermittent renewable energy supply systems. CAES has special requirements for compressor(e.g. heavy load, high pressure ratio, wide range). With advantages of higher efficiency and wider operation range, IGC(Integrally Geared Compressors) is selected to fulfill the special requirements of the large-scale CAES. To get a better aerodynamic performance, in this paper, based on the analysis of internal flow of centrifugal compressor, a multi-objective one-dimensional optimization design program was put forward combined with modified Two-Zone model and a low solidity vaned diffuser(LSVD) design method. Then, a centrifugal compressor aerodynamic component optimization design system was established with the three-dimensional blade optimization design method based on neural network and genetic optimization algorithm. Then a validation was done by redesigning the Krain-Impeller to get better performance. Finally, the aerodynamic design of the first stage of IGC was completed. The CFD calculation results indicated that the total-to-total pressure ratio of the first stage was 2.51 and the polytropic efficiency was 91.0% at the design point. What’s more, an operation margin and surge margin of the compressor was about 26.5% and 16.4% respectively.     

Current application situation and development prospect of physical energy storage technologies

作为可再生能源并网的关键技术,可再生能源的高速发展也带动了储能产业的发展和成熟。物理储能技术,发展历史长,技术较为成熟,部分已实现商业化运作;以抽水蓄能为代表,是电网调峰的主力,也在储能市场容量中占据着绝对份额。但无论是传统抽水蓄能,还是压缩空气储能都对环境、地理地质条件有较高的要求,极大地制约了这些技术的普遍推广和应用。因此物理储能也经历着应用模式的变革、传统技术向新兴技术转化的过程。虽然抽水蓄能、压缩空气储能和飞轮储能三种物理储能技术在原理、应用领域、安装容量以及未来发展趋势上各不相同, 但作为战略新兴技术,都需要技术的突破、政策和资金的支持以及更多的市场应用机会。     

Baseload electricity from wind via compressed air energy storage (CAES)

This study investigates two methods of transforming intermittent wind electricity into firm baseload capacity: (1) using electricity from natural gas combined-cycle (NGCC) power plants and (2) using electricity from compressed air energy storage (CAES) power plants. The two wind models are compared in terms of capital and electricity costs, CO₂ emissions, and fuel consumption rates. The findings indicate that the combination of wind and NGCC power plants is the lowest-cost method of transforming wind electricity into firm baseload capacity power supply at current natural gas prices (∼$6/GJ). However, the electricity supplied by wind and CAES power plants becomes economically competitive when the cost of natural gas for electric producers is $10.55/GJ or greater. In addition, the Wind-CAES system has the lowest CO₂ emissions (93% and 71% lower than pulverized coal power plants and Wind-NGCC, respectively) and the lowest fuel consumption rates (9 and 4 times lower than pulverized coal power plants and Wind-NGCC, respectively). As such, the large-scale introduction of Wind-CAES systems in the U.S. appears to be the prudent long-term choice once natural gas price volatility, costs, and climate impacts are all considered.     

The value of compressed air energy storage in energy and reserve markets

Storage devices can provide several grid services, however it is challenging to quantify the value of providing several services and to optimally allocate storage resources to maximize value. We develop a co-optimized Compressed Air Energy Storage (CAES) dispatch model to characterize the value of providing operating reserves in addition to energy arbitrage in several U.S. markets. We use the model to: (1) quantify the added value of providing operating reserves in addition to energy arbitrage; (2) evaluate the dynamic nature of optimally allocating storage resources into energy and reserve markets; and (3) quantify the sensitivity of CAES net revenues to several design and performance parameters. We find that conventional CAES systems could earn an additional $23 ± 10/kW-yr by providing operating reserves, and adiabatic CAES systems could earn an additional $28 ± 13/kW-yr. We find that arbitrage-only revenues are unlikely to support a CAES investment in most market locations, but the addition of reserve revenues could support a conventional CAES investment in several markets. Adiabatic CAES revenues are not likely to support an investment in most regions studied. Modifying CAES design and performance parameters primarily impacts arbitrage revenues, and optimizing CAES design will be nearly independent of dispatch strategy.     

Modelling and management of smart microgrid for rural electrification in sub-saharan Africa: The case of Nigeria

Access to electricity is still a challenge in many parts of sub-Saharan Africa. In Nigeria, over 70% of the rural dwellers do not have access to electricity. The purpose of this paper is to examine the potential of a smart microgrid for off-grid rural electrification in Nigeria. A combination of design thinking and model-based design methodology is employed to select a suitable microgrid configuration and to develop a smart microgrid model. A system consisting of a solar photovoltaic array, battery energy storage and a diesel generator is selected, and the model is developed in Simulink. Demand data from 10 rural communities in Nigeria are used to validate the performance of the model and the potential for demand management is considered. The use of energy efficient light bulbs is found to reduce the peak electricity demand of the case study communities by 42 to 76%. Combining the proposed system with the use of LED bulbs makes the system to have 56 to 81% less net present cost than a system with a diesel generator alone and incandescent light bulbs. The proposed smart microgrid is found to be more suitable for off-grid rural electrification in Nigeria than diesel generators which are currently used for off-grid electrification in Nigeria.     

System behaviour of compressed-air energy-storage in Denmark with a high penetration of renewable energy sources

In 2005, wind power supplied 19% of the 36 TWh annual electricity demand in Denmark, while 50% was produced at combined heat-and-power plants (CHP). The installed wind-turbine capacity in Western Denmark exceeds the local demand at certain points in time. So far, excess production has been exported to neighbouring countries. However, plans to expand wind power both in Denmark and in its neighbouring countries could restrain the export option and create transmission congestion challenges. This results in a need to increase the flexibility of the local electricity-system. Compressed-Air Energy-Storage (CAES) has been proposed as a potential solution for levelling fluctuating wind-power production and maintaining a system balance. This paper analyses the energy-balance effects of adding CAES to the Western Danish energy-system. Results show that even with an unlimited CAES plant capacity, excess power production is not eliminated because of the high percentage of CHP production. The optimal wind-power penetration for maximum CAES operation is found to be around 55%. The minimum storage size for CAES to fully eliminate condensing power plants operation in the optimized system is over 500 GWh, which corresponds to a cavern volume of around 234 Mm³ at an average pressure of 60 bar. Such a storage size would be technically and economically unfeasible. The analysis, however, did not include the potential role of a CAES plant in regulating the power services.