Liu, Hongshun, Xia, Tian, He, Dongxin, Han, Mingming, Li, Qingquan, and Duan, Yubing
Highlights • First, based on the general form of Maxwell's equations, the field source is transformed into an equivalent form with a constraint source, and a full-current PEEC model with a surface charge component element is established. • Second, a fast and accurate calculation of the inductance parameters of SCSR components involving multiple integrals is carried out using the geometric mean distance and complex component division. • Third, the equivalent structure and circuit equations for the SCSR internal windings are given, and the variation of winding resistance and inductance parameters with VFTO frequency is analyzed. Abstract Stepped Controlled Shunt Reactors (SCSRs) have advantages of flexible control and reliable compensation and are likely to become widely used in Ultra-High-Voltage/Extra-High-Voltage (UHV/EHV) transmission systems. Very fast transients that occur in such systems will generate a Very Fast Transient Overvoltage (VFTO) in the SCSR. This may cause damage to the SCSR and lead to system losses. In this paper, the electric field strength and magnetic induction intensity are taken as the basic physical variables when these transients occur. Maxwell's equations are used to separate the constraint sources, such as the conduction current, magnetization current, and polarization current, from the field source. Then, an all-current Partial Element Equivalent Circuit (PEEC) model for these component elements that considers the surface charge is established. Fast and accurate calculations of the inductance parameters, which involve multiple integrals, are performed using geometrical mean distances and a complex component segmentation method. The equivalent structures and circuit equations of the SCSR windings are presented, and the voltage distribution of the SCSR windings under VFTOs of different frequencies is obtained. The results show that, the voltage waveform in the SCSR windings more rapidly attenuates as the VFTO frequency increases. The peak value of the oscillating voltage in the high-voltage winding of the SCSR is higher than that in the low-voltage winding. [ABSTRACT FROM AUTHOR]