Search

With the expansion of distributed power systems and renewable energy worldwide, the use of synchronous condensers (SC) has been gradually increasing to maintain the power quality of an electric grid. Because SC generates fewer harmonics and has the advantage of strengthening system inertia, it is considered as a primary option in Korea over other options such as Static Var Compensator (SVC) and STATic synchronous COMpensator (STATCOM). If superconductor synchronous condenser (SSC) is applied instead of SC, it brings more advantages: (1) it can minimize the adverse impact on the power system due to lower synchronous reactance, and (2) the higher power density can lead to many advantages in a limited area of substation. With these backgrounds, we report a design study on 40 MVAr SSC with no-insulation high-temperature superconductor (NI-HTS) field coil. Firstly, design criteria and procedures for electromagnetic design were set. Secondly, with the design procedure, the electromagnetic design having the minimum HTS conductor usage was obtained among the designs satisfying design criteria. Based on the final design, key characteristics of SSC including no-load voltage, the maximum flux density under the rated-load condition, V-curve characteristic, synchronous reactance, zero sequence reactance, negative sequence reactance, critical current, and NI-HTS characteristics were calculated by using finite element method. Lastly, the design comparison between SSC and SC was presented. • The use of synchronous condensers has been gradually increasing. • Superconductor synchronous condenser is a promising alternative option. • It has not only a much lower synchronous reactance but also a higher power density. • The advantages were confirmed through the electromagnetic design study. [ABSTRACT FROM AUTHOR]

This paper presents a design study of a low-speed, high torque 20 kW class motor with a high-temperature superconductor (HTS) field coil for a liquid hydrogen centrifugal pump. The motor is designed based on three key concepts: 1) employing an axial-flux motor topology that can increase torque density by reducing the axial length together with a centrifugal pump; 2) using liquid hydrogen in a pump as a coolant for HTS coil; 3) adopting no-insulation (NI) YBCO solenoid coils as field coils of the motor to improve coil protection as well as mechanical stability. In the design process, first, an electromagnetic design of the axial type motor is obtained considering the required performance of previous commercial pumps. Considering the current and temperature margin to secure the HTS coils' stable operation, two types of HTS coils (solenoid type and triangle type) are designed and their performances are compared. Second, to evaluate validity of the electromagnetic designs, mechanical stresses in the HTS coils are estimated. By comparing the solenoid type and the triangle type, it is confirmed that the solenoid type has a distinct stress-reducing effect in terms of magnetic stress as well as rotational stress. Our design study results show the potential superior performance of the axial flux motor with HTS coils for several tens of kW applications with low speed and high torque loads such as liquid hydrogen pumps. • 20 kW class superconducting motor for a liquid hydrogen centrifugal pump is designed. • An axial motor topology and a superconducting coil are applied for low speed, high torque application. • The solenoid-type coil shows a distinct stress-reducing effect compared to the triangle-type coil. • A centrifugal pump with a HTS motor can be a prominent alternative to previous pumps. [ABSTRACT FROM AUTHOR]