电力系统设备的超导磁储能原文及翻译.doc

Superconducting Magnetic Energy Storage for Power System Applications电力系统设备的超导磁储能Abstract-A survey of the technology of superconducting mag-netic energy storage (SMES) was made. This technology is at-tractive for its high efficiency and fast response, but also dubious for the capital investment. Research made in the USA and Japan resulted in several conceptual designs for the utility scale SMES systems. Experiments on power system models proved that SMES systems offer other benefits in addition to energy storage. Economic evaluations showed that the SMES is competitive with pumped hydro, especially when the energy price hikes. A power flow program is used to verify the application of a SMES plant to the Taiwan power (Taipower) system摘要一个关于超导磁能储存的技术被研发出来了。这项技术涉它高效且响应速度快，但是相关投资经费却被怀疑。在美国和日本的研究导致了几项公共事业项目SMES系统的概念设计。电力系统模型实验证明出除了能量储存，SMES系统还提供了其他的好处。经济测度显示SMES在水电方面很有竞争力，特别是在能源价格上涨的时候。功率流方案被用于去证明SMES的设备被安插在了台湾的dialing系统中。I. INTRODUCTION前言SINCE the discovery of superconductivity, people have expected a revolution to occur in the field of electrical engineering. However, the conditions of low transition temper-ature (Tc), critical magnetic field and critical current density have limited the applications of the superconductors. Several new superconductive materials of high transition temperature have been announced since 1987. The high T, supercon-ductors have been considered helpful to reduce the cost of superconducting equipment and expand the applications of superconductors. The application of the SMES on an electric power system was first proposed in 1969. This idea is to charge the superconducting magnet with the surplus generation of the base load units during off-peak time, and discharge to the ac system during peak time. Using a SMES plant, large thermal and nuclear units can constantly operate at the optimal output and pick up the peak load without installing too many peaking units. The SMES system can also benefit the power system by increasing the capacity of a transmission system, reducing transient overvoltage, enhancing the spinning reserve and regulating system voltage. Of course, a single SMES unit cannot serve those functions with the same design criteria. The most remarkable features are the high efficiency of more than 90% and the fast response in milliseconds.自从发现超导后，人们期待在在电气工程领域里有改革。然而，低转变温度，临界磁场领域和临界电流密度限制了超导应用设备。在1987年后一些高传输温度超导材料被研制出来了。因为高温，超导被认为有效地减少了超导设备和和超导应用扩展的成本。电力设备中的SMES应用设备在1969年首次被提出。这个想法是用来使基本负荷机组的超导磁铁在非繁忙时间时充电，在繁忙时间时给系统放电。使用SMES插件，大型热核电机组能够在最佳输出时连续操作并且不用安装太多峰值元件去识别峰值负荷。SMES系统能够通过增加传输系统的容量，减少瞬态过电压，提高储备和规范系统电压来使功率系统获利。当然，一个单独的SMES元件不能用相同设计标准来实现这些功能。突出特点是高效性超过90%，在毫秒级别就可以快速响应。The economic size of a utility SMES system was estimated at 5000 MWh and 1000 MW. Different evaluation showed that the SMES system of this size was competitive compared to other energy storage technologies. Researchers in the USA and Japan predicted the utility SMES systems to be available by the end of this century or early twenty-first century.一个效用SMES系统的经济规模大概在5000MWh和1000MW。不同的评价说明SMES系统的大小与其他能量储存技术相比很有竞争力。美国和日本的研究预测效用SMES系统在本世纪或者21世纪初期就会被使用。II、APPLICATIONSOF SUPERCONDUCTORS ON ELECTRICPOWER SYSTEMS 电力系统的超导应用设备Superconductors have been proposed to be used on re-search application, electrical standards, RF signal processing and transmission, computer components and systems, energy conversion, power transmission, transportation, and medical instruments. Zero resistivity and the Josephson effect are the essential properties upon which the proposed applications are based. The applications on power systems can be energy storage, transformers, generators, transmission lines, and the miscellaneous. 超导早被建议使用在研究性设备，电力水平，射频信号产生和传输，电脑组件和系统，能量转化，功率传输，传导，医用设备方面。在建议应用设备的基础上零电阻和约瑟夫森效应是基本属性。建立在电力系统上的应用设备能储存能量，传输器，发电机，输电线路和冗余。A. Application on Power System Apparatus对电力系统设备的应用The large size and heavy weight seem to force the capac-ity of traditional transformers against a limit. Thus power industries thought that replacing normal conductor windings with superconductors might solve this problem. The first laboratory scale SC transformer was made and worked well as early as 1961. However, commercialized ones had been considered infeasible because of the high ac losses of windings and the difficulties of cryostat design. Until 1983, wires of superconducting ultra-fine filaments embedded in Cu-Ni matrix were proved to be of low ac loss and high resistance when beyond critical current, the feasibility of superconducting transformers were rethought.大尺寸和重量重似乎迫使反对限制传统变压器的容量。因此电力行业认为用超导代替一般导体绕组可能会解决这个问题。早于1961年首个实验室规模的SC变压器被研制出来并工作的很好。然而，商业化的系统被认为不可行，因为绕组的交流损耗高，低温恒温器设计困难。直到1983年，嵌在铜镍基中的超细丝超导电线被证明在超出临界电流时交流损耗低和高耐，超导传输器的可用性才被在此考虑。Superconducting synchronous generators have been inves-tigated and fabricated in many countries since M.I.T. success-fully developed a 45 kVA SC generator in 1969. In early years, superconductors were used only in field windings because of the high ac loss of armature winding if using superconductors. The development of ultrafine filamentary wires has changed the situation. In addition to the high efficiency and the reduc-tions in size and weight, the low synchronous reactance of the superconducting generator was reported to be able to signifi-cantly increase the capacity of transmission lines connected to the generator 11. Magnetohydrodynamics (MHD) generators are generally considered for use on marine for the smaller size and less noise. Yet a combination of an MHD generator with a conventional steam power plant was proposed. This arrangement can increase the efficiency of the plant from 40% to 50% and reduce the emission of pollutants 2. In the mid-l960s, groups in Japan and Austria began their research on superconducting power transmission, and more was conducted in United States, U.S.S.R., and Europe in the following decade 3, 4. Experimental results proved no unconquerable technical difficulties on both cryogenic technique and low temperature dielectric design. Economic evaluation made by one of the European groups indicated that a 400 kV superconducting transmission line would cost more than an internally watercooled 400 kV line if the power level did not exceed 5000 MVA 2. Philadelphia Electric Company estimated the cost of a 230 kV superconducting transmission line was less than any other underground cable based on 106 KM transmission distance and 10 GVA capacity 3. In Japan, the economical scale for superconducting power transmission was 500 kV, 8 GW and 80 KM transmission distance taking account of 10-year running costs 4. 自从1969年M.I.T.成功的研制出45KVA的SC发电机后，超导同步发电机曾被调查和在横多国家被捏造出来。早期在使用超导时因为交流损耗高的缘故超导被应用在励磁绕组中。抄袭导线改变了这个事实。出来高效和尺寸减小外，低超导同步发电机的电抗能够增加连接发电机的传输线路的容量。因为MHD发电机体积小噪音小被使用在海洋研究上。然而一个磁流体发电机和传统的蒸汽动力装置的组合就被提出来了。这样的安排可以将电厂的效率从40%提高到50%，并减少污染的排放。在19世纪60年代中期，日本和澳洲的组织开始了他们对超导电力传输的研究，随后的10年更多是来自美国U.S.S.R和欧洲。试验结果证明，低温技术和低温介质技术设计没有不能克服的技术困难。一个欧洲团队引起的经济评估表明，如果电力层次不超过5000MVA，400 kV的超导传输线会比内部水涂层的400KV线花费更多成本。Philadelphia电力公司估计，230KV的超导传输线比任何其他基于106KM传输距离和10GVA电容的地下电缆的成本都低。在日本，超导电力传输经济规模是500KV，8GW和80KM传输距离，考虑到10年的运行成本。Supertransductors are used as fault current limiters by introducing inductance into a power circuit when the current exceeds a predetermined level. As shown in Fig. 1, the coil in series with the power line is interleaved with a superconducting coil which carries a large dc bias current to drive the iron core into the saturation region. Because of the saturation of the core, normal ac current cannot cause flux change in the series coil, thus no voltage drop across the coil. When the fault current is large enough to drive the core back to normal region, it will make the series coil a large impedance. Hence, the fault current can be limited to a value determined by the bias current 2, 5超导传感器被用作故障电流限制器，通过当电流超过预测等级时将电感引入电源电路来限流。如图1所示，串联线圈和电源线与超导线圈相交错，超导线圈带有一个大的直流偏置电流来驱动铁心使其进入饱和区。由于核心饱和，正常的交流电流不能导致串联线圈中磁通量变化，因此没有电压通过线圈。当故障电流大到足以驱动核心返回到正常区域，它会使串联线圈阻抗增大。因此，故障电流由偏置电流限制在一个值。B. Superconducting Magnetic Energy Storage超导磁储能The SMES systems convert the ac current from a utility system to dc current flowing in the superconducting coil and store the energy in the form of magnetic field. The stored energy can be released to the ac system when necessary. The charge and discharge rates are controlled by adjusting the delay angle of converter at a rapid speed. Thus SMES systems are considered to have the potential of applications for the load leveling of a power system and the damping of system oscillations. In addition to conceptual designs of large scale SMES units, a relatively small SMES system for system stabilization was installed and tested in the United States 6.超导磁储能系统将实用系统的交流电流转换成超导线圈中流动的直流电，并以磁场的形式储存能量。需要的时候，储存的能量可以释放到交流系统中。充电放电的速率是通过快速调整整流器的延迟角来控制的。因此超导磁储能系统被认为在电力系统的负载均衡和系统振荡阻尼的应用中很有潜力。除了大范围的超导储能系统机组的内容设计之外，美国已经构建并测试了一个用于系统稳定的相对较小的超导储能系统。The idea of SMES for load leveling of a power system was first proposed by Ferrier in 1969. The earliest fundamental R&D and conceptual design work on SMES were initiated by H. A. Peterson and R. W. Boom at the University of Wisconsin (UW) the next year. Due to the energy crisis, many projects on SMES research funded by the Department of Energy, National Science Foundation and Electric Power Research Institute were carried out in the 1970s. In addition to U W , Los Alamos National Laboratory, Bechtel Group Inc., General Atomic Technologies Inc., and General Dynamics all got involved. In Japan, the National Laboratory for High Energy Physics, New Energy Development Organization, Central Research Institute of Electrical Power Industry and the Osaka University, etc., have directed efforts on SMES researches.电力系统负载均衡的超导储能系统的概念最先在1969年被Ferrier提出。第二年，最早的基本R&D和超导储能的内容设计工作在Wisconsin大学由H. A. Peterson and R. W. Boom首先展开。由于能源危机，许多由能源部、国家科学基金会和电力电子研究会资助的SMES的项目研究在19世纪70年代开始进行。除了Wisconsin大学之外，洛杉矶国家实验室，德尔集团股份有限公司，通用原子技术股份有限公司，通用动力也参与了。在日本，高能物理国家实验室，新能源开发组织，电力工业中央研究机构和大阪大学等，为SMES研究做出了贡献。Large-scale SMES systems are expected to be available for utility commitment by the late 1990s in the United States 7 . In Japan, they originally foresaw a necessity and availability of the SMES systems by the year 2000, but there was a 15-year delay according to a newly modified schedule 8, 191. In addition to the load leveling and peak shaving of a power system, the SMES system has the following advantages.大范围的SMES系统曾被期望在19世纪90年代末的美国用于实际应用。在日本，他们在2000年最先预见到SMES系统的必要性和可行性，但是根据最新修改的日程，这项计划延迟了15年。除了电力系统的负载均衡和峰值调整之外，SMES还有以下优点：1)Energy savings. The savings of energy result from two aspects. The base-load generators can operate at most efficient conditions. The efficiency of SMES is higher than that of pumped hydro storage, which is about 70%. Although there is no consistent efficiency of SMES so far, it has been believed to be more than 90% taking account of the power required for refrigeration.节能。从两个方面实现节能。基础负载发电机能在最有效率条件下运行。SMES比效率为70%泵水力存储的效率高。虽然SMES至今还没有一致的效率，但即使考虑制冷功率，它的效率仍被认为有90%以上。2)Power system stabilization. A 30 MJ SMES system was built at Tacoma Substation, Washington, to damp the oscillation observed on the 500 kV Pacific ac Intertie. The experimental operation proved that the SMES system could increase the stability limit of the Pacific ac Intertie from 2100 to 2500 MW lo.电力系统稳定。为了使太平洋一条500KV的交流线阻尼，美国华盛顿塔科马变电站建立了一个30MJ的SMES系统。实验操作证明SMES系统能家将太平洋交流线的稳定极限从2100MW增加到2500MW。3)Peak shaving of transmission line. If the SMES unit is located near the load center, the load leveling of the transmission line connecting the load center and generation center can be reasonably expected.输电线路调峰。如果SMES机组位于负载中心附近，那么与负载中心连接的的传输线路的负载均衡和发电中心可以被合理预期。4)Rapid supply for spinning reserve. Because of the fast response of ac-dc converter, the SMES units can serve as the spinning reserve.运转备用的快速供应。由于AC-DC整流器的快速响应，SMES系统可以作为运转备用。5)Voltage regulation. The real and reactive power of a SMES unit can be controlled independently. By absorbing and providing reactive power, the SMES can serve the similar functions of static var compensation device.电压调节。SMES机组的实际功率和无功功率可以被独立控制。通过吸收和提供无功功率，SMES可以有静止无功补偿装置的类似功能。6)Less geographical constraints. The SMES units can be built anywhere beneficial to a power system, provided the bedrock can support the SMES structure. On the contrary, only few mountainous sites are suitable for pumped hydro plants, and normally long transmission lines are required to connect the power plants and the bulk transmission system.地域限制小。只要有可支持SMES结构的基岩，SMES机组可以在任何有益于电力系统的地点建立。反之，只有少数的山区地点适合建泵水力发电厂，通常要求长传输线与电厂和大容量传输系统相连接。However, there are disadvantages concerning the SMES system.然而，SMES系统也有缺点：1) Magnetic leakage flux. The magnetic field produced by a SMES unit is time varying with a dc offset. The field is maximum when fully charged in the morning and minimum when discharged in the early evening. The magnetic field drops as the distance from the coil increases. The toroidal coil will confine the flux inside the coil, thus is free from the flux leakage problem. But, the energy storage effectiveness of a toroid is about 30% less than that of a low aspect ratio thin-walled solenoid. This means a large increase of capital cost which is already another disadvantage. 漏磁，SMES机组产生的磁场是随着直流抵消时变的。在早上充满电时磁场最大，傍晚放电时磁场最小。磁场随线圈的距离增加而减小。环形线圈将把磁通量局限于线圈之内，从而使其不会有漏磁。但是，环形线圈的能量储存效率比低长宽比薄壁电磁低30%。这意味着资本成本将大量增加，这已成为另一个缺点。2) High capital investment. The estimated capital cost of a 5000 MWh, 1000 MW SMES plant is five times as much as a pumped hydro plant of the same capacity 111. Though the overall evaluations made by the Bechtel group and the National Laboratory for High Energy Physics in Japan show a better potential for the SMES technology, the large investment has been a negative factor.高资本投资。评估可得一个5000 MWh, 1000 MW SMES电厂的资本成本约为同样容量的泵水力电厂的5倍。虽然贝克集团和日本高能物理国家实验室的整体评估表明了SMES技术更好的潜力，但是高额的投资仍然是一个消极因素。3) Emergency energy release. In case of coil failure, the stored energy must be quickly released to prevent the coil from being damaged. Thus a more reliable protection measure is required for the SMES system. If the energy is released to the ac system, it might shock the ac system. In some conceptual designs, the energy is to be dissipated in superconducting cable and its support structure. 紧急能量释放。在线圈故障的情况下，储存的能量需要被快速释放，以避免线圈被损坏。因而SMES系统需要更可靠的保护措施。如果将能量释放到直流系统，也许会严重影响到直流系统。在一些概念设计中，能量将在超导电缆和其支持结构中被释放。4) Long precooling time. It is estimated to take about four months to cool the superconducting coil from room temperature to operating temperature 8. In case of emergency energy release, it needs at least the same time to recover according to the coil protection scheme in the Bechtel design 12. The long precooling time will reduce the availability of the SMES system. 预冷时间长。据估计要将超导线圈从室温降到操作温度，需要花大约4个月来冷却。如果遇到紧急能量释放，根据贝克设计的线圈保护时间表，超导线圈需要至少相同的时间来恢复。较长的预冷时间会降低SMES系统的可行性。III. COMPONENT OF THE SMES SYSTEMSMES系统的成分A SMES system is composed of power conditioning, super-conducting magnet, cryogenics, coil protection, and controller.一个SMES系统由功率调节器，超导磁体，低温部分，线圈保护部分和控制器组成。The power conditioning is the interface between the utility ac grid and the superconducting magnet. The power conditioning system consists of transformers, solid state converters, a firing circuit, a harmonics filter and a reactive power compensating device. Typical solid-state converters employ two sets of 6-pulse SCR Graetz bridges connected in series, controlled by a firing circuit. Because of the delay angle of the SCR is limited to Oo-18O0, the SCR converters always draw lagging reactive power. Thus VAR compensating device is required. There are two measures to prevent or alleviate VAR compensation problem. One is adopting the combined GTO and SCR Graetz bridges 13, the other is asymmetrically controlling the delay angle of the upper and the lower S C R s of the bridge 14. Harmonics produced by the converter can be partly removed by using bridges of higher pulse number or using a delta and a wye transformer.功率调节器是使用交流电网和超导磁体之间的接口。功率调节器系统由变压器，固态转换器，发射电路和谐波滤波和无功补偿装置组成。典型的固态转换器采用两套串联的6脉冲的可控硅格雷茨桥，由发射电路控制。由于SCR的延迟角被限制在0到180，SCR转换器总是延迟无功功率。因此需要无功补偿装置。有两种方法可以阻止或缓和无功功率装置问题。一种是采用门电路和SCR桥相结合的方法，另一种是不对称控制上层或下层SCR桥的延迟角。转换器产生的谐波部分可以使用有更高脉冲的桥或使用增量或Y型变压器。The superconducting magnet is used to store energy and must be strong enough to withstand the large Lorentz forces when energized. The basic construction of a superconducting cable is thousands of superconducting filaments imbedded in copper alloy or aluminum alloy to make a filamentary composite, several filamentary composites stranded with copper wire to constitute a subcable, and a number of subcables laid in the gloves of the stabilizer to complete the cable. The A15 compounds such as NbTi and Nb3Sn are the most popular materials of the superconducting filaments. For the economical superconductor usage and the simplification of the coil support assembly, the low aspect ratio solenoid was accepted in most of the conceptual designs.超导磁体是用于储存能量的，且要强到通电时能承受很大的洛伦兹力。超导电缆的基本结构是由成千上万嵌入铜合金或铝合金的超导细丝构成的长纤符合材料，几根长纤复合材料和铜线一起组成了次级电缆，几根次级电缆又一起被外层包裹，形成完整的电缆。如NbTi和Nb3Sn等这些A15化合物是制造超导细丝最长用的材料。为了经济地使用超导和使线圈支持组建简化，低宽高比的电磁是概念设计中被广泛接受的。The cryogenic system is required to cool the magnet and keep it at the operating temperature. Essentially the cryogenic system is composed of refrigerators, vacuum pumps, helium tank and pipes, and a dewar. The dewar consists of a vacuum vessel, thermal shields, and a helium vessel enclosing the coil. The stainless steel vacuum vessel thermally insulates the coil from ambient temperature. The thermal shields are made of aluminum sheet attached with cooling tubes. They are positioned between the walls of the helium vessel and the vacuum vessel to reduce the thermal radiation. It is estimated to take about four months to cool the coil from room temperature to operating temperature 8. In the steady-state operation, the cryogenic system has to compensate for the heat losses and the coil ac loss