As electric power systems grow and become more interconnected, the fault current levels increase. Superconducting fault current limiters (SFCL) can limit the prospective short-circuit currents to lower levels, so that the underrated switchgears can be operated safely. In order to introduce SFCL into the electric power system, we need a way to conveniently predict the limiting characteristics in a given situation. We have developed an Electromagnetic Transient Program (EMTP) model of high temperature resistive type SFCL based on the electric field (E)-current density (J) characteristic of the superconductor. The SFCL in series with a circuit breaker could be practically used in electrical distribution systems. Case studies of EMTP simulations show that the SFCL cannot only limit the fault current to an acceptable value, but also reduce voltage decrease and the rise rate of the transient recovery voltage. In order to ensure the safe and proper usage of SFCL, some future considerations on the interaction between SFCL and power systems are presented as well.

In order to introduce the high temperature superconducting fault-current limiters (SFCL) into electric power systems, we need a way to conveniently predict the limiting characteristic in a given situation. The most important physical property dominating the current limiting behavior of the SFCL is the electric field-current density (E-J) characteristics of High Temperature Superconductors (HTS) which is dependent on temperatures. So we have developed an EMTP/ATP model of high temperature resistive type SFCL using MODELS language based on characteristics of HTS. Real-time circuit current is as an input signal to the SFCL model, and the output of the model is controlled by a TACS-controlled time-dependent resistance. The operating characteristics and limitation behaviors of SFCL have been investigated in detail.

利用户用风力发电系统开发广大农村地区风能资源，可以有效缓解农村地区用电难问题。通过分析风速、风轮机和永磁同步发电机的数学模型，在电力系统电磁暂态软件平台上建立户用风力发电系统仿真模型，并对户用风力发电系统在离网运行模式下的负载跟踪控制策略进行研究，给出户用风力发电系统离网运行控制策略。仿真结果表明：根据文章所提出的离网运行控制策略，户用风力发电系统能够及时响应风速变化并跟踪负载变化。

在EMTP/ATP软件平台中建立了包含风速、风轮机、传动装置以及鼠笼异步发电机的恒速恒频风力发电系统整体模型；利用所建模型对恒速恒频风力发电系统的并网以及运行特性进行了仿真研究。仿真结果表明：所建模型能详细描述恒速风力发电系统，具有一定的通用性，对于EMTP/ATP元件库是一个很有效的扩展；发电机转子转速接近同步转速时并网能有效减小并网时对电网的冲击。

在考虑了光照强度和电池温度2种因素对太阳能电池技术参数和输出特性影响的基础上，采用了太阳能电池的实用化数学模型，在电力系统电磁暂态软件平台EMTP/ATP上利用MODELS语言和TACS功能搭建了太阳能电池的通用仿真模型。该模型的功能主要是通过改变短路电流，开路电压，最大功率点电流、电压等太阳能电池板的技术参数，研究不同型号太阳能电池板的伏安特性和功率特性。并针对3组不同光照强度和电池温度。对太阳能电池板的伏安特性和功率特性进行了仿真研究。研究结果表明：随着光照强度的减小，太阳能电池板的最大输出功率也减小；随着电池温度的减小。太阳能电池板的最大输出功率呈上升态势。

In power systems, superconducting fault current limiters (SFCLs) can limit the prospective short-circuit currents to lower levels, so that the underrated switchgears can be operated safely. This paper presents a detailed theoretical analysis of improving power system stability by using of SFCLs. Electromagnetic Transient Program (EMTP) simulation results based on a model system also show that SFCLs are effective for enhancing the transient stability of electric power systems by restraining the generator rotors from accelerating after faults and improving power quality. This paper outlines the basic application guidelines for using superconducting fault current limiters in different voltagelevel power systems. In order to insure the safe and proper usage of SFCLs, some future considerations on the interaction between SFCLs and power systems are presented as well.

Transport AC loss measurements have been made on YBCO-coated conductors prepared on two different substrate templates-RABiTS (rolling-assisted biaxially textured substrate) and IBAD (ion-beam-assisted deposition). RABiTS samples show higher losses compared with the theoretical values obtained from the critical state model, with constant critical current density, at currents lower than the critical current. An origin of this extra AC loss was demonstrated experimentally by comparison of the AC loss of two samples with different I-V curves. Despite a difference in I-V curves and in the critical currents, their measured losses, as well as the normalized losses, were practically the same. However, the functional dependence of the losses was affected by the ferromagnetic substrate. An influence of the presence of a ferromagnetic substrate on transport AC losses in YBCO film was calculated numerically by the finite element method. The presence of a ferromagnetic substrate increases transport AC losses in YBCO films depending on its relative magnetic permeability. The two loss contributions-transport AC loss in YBCO films and ferromagnetic loss in the substrate-cannot be considered as mutually independent.

Transport ac losses of parallel arrays of superconducting tapes with an elliptical cross-section carrying mutually anti-parallel currents were modeled numerically by finite element method. Two different configurations-tapes positioned edge to edge (x-array) and tapes positioned face to face (y-array) were considered. It was found that an x-array increases the losses while a y-array decreases them-relative to infinitely distant tapes. The highest ac loss decrease is observed when the tapes are close to each other in y-array. The AC loss of a y-array made of various numbers of tapes was compared with the loss of an array made of round wires. It was found that y-arrays of tapes have lower loss than arrays of round wires. Bringing y-arrays of tapes close to each other in the x direction causes a significant increase in ac loss. The present analysis may be useful if considering fault current limiters made of straight conductors in a meandering configuration. The results are qualitatively valid also for a fault current limiter made of non-inductive (bifilar) windings in the form of several pancake coils, each coil wound non-inductively (i.e. with anti-parallel currents).

When electric power systems are interconnected in operation, the fault current levels increase. This problem can be solved by deploying a bus-tie Superconducting Fault Current Limiter (SFCL) in distribution substations which allows two buses to be tied without significantly raising fault current levels. The Alternative Transient Program (ATP) version of Electromagnetic Transient Program (EMTP), ATPDraw and The Output Processor (TOP) are applied to investigate the operational behavior of the SFCL in a parallel connection of radial supply systems. The case study showed that an SFCL on bus tie location can not only suppress the fault current levels effectively but also improve the power quality and the reliability of the supply network. The simulation results will be presented and discussed in detail.

以电力系统电磁暂态分析软件EMTP/ATP为平台，采用电机矢量控制技术以及比例-积分调节器串联校正等方法建立了双馈风力发电系统的电磁暂态仿真模型，该模型包括风速模型、风力机模型、双馈发电机模型，以及有功、无功解耦控制系统的模型。依据变速风电机组的运行特性对该模型进行了仿真研究，仿真结果验证了该模型的有效性。