Modeling and impacts analysis of energization transient of EHV/UHV magnetically controlled shunt reactor

Abstract

To address the problems of overvoltage, harmonic distortion, and mal-operation that can occur in protection systems as a result of direct energization in magnetically controlled shunt reactors (MCSRs), this paper proposes a novel approach for MCSR energization-namely, pre-excited energization. Using the structure and operating principles of an MCSR, a detailed derivation of energization transient mathematical model for both direct and pre-excited energization are presented and the model-specific impacts of the 2 different energization modes are investigated. To validate the theoretical analysis, we performed physical model tests and simulations of different energization modes. The results indicate that pre-excited energization is capable of suppressing overvoltage on the DC link bus and alleviating harmonics caused by direct energization. KEYWORDS energization, impacts analysis, magnetically controlled shunt reactor (MCSR), mathematical model, transient characteristics 1 | INTRODUCTIONControllable shunt reactors placed on line terminals or substation bus bars play an important role in extra high-/ultra high-voltage (EHV/UHV) transmission networks of voltage control and reactive power compensation. 1-3 With the advantages of continuously adjustable capacity, 4 low harmonics, 5 and excellent steady-state control characteristics, 6 magnetically controlled shunt reactors (MCSRs) are preferable for reactive power compensation in EHV/UHV power systems. Energization of power system components is accompanied by a switching transient, 7,8 and the energization transients of components such as transformers, 9-11 shunt capacitor banks, 12-14 and conventional shunt reactors 15 have been well documented. However, owing to their special body structures, MCSR energization transients are more complicated than those of conventional shunt reactors and transformers, and there has not been much research so far on the energization of MCSRs. 16 The simplest energization strategy for MCSRs at present is direct energization, in which the DC excitation system is blocked. As with transformer energization, one of the main problems associated with the MCSR direct energization transient is the occurrence of inrush current with a large number Symbols: _ U m , System bus voltage where MCSR is equipped; α, Phase angle of the system bus voltage at the instant of energization; U k , DC excitation source voltage; i 1 , Current of the grid-side winding; i k , Current of the control winding in the single phase MCSR; R 1 , Resistance of the grid-side winding; R k , Resistance of the control winding; R w , Balance resistor; N 1 , Number of turns in the grid-side winding; N 2 , Number of turns in the control winding; N 3 , Number of turns in the compensation winding; A, Area of the iron limb; l, Magnetic path length of the iron limb; i kA , Current of phase A in the control windings; i kB , Current of phase B in the control windings; i kC , Current of phase C in the control windings; i t , Total current of control windings; I dc , DC excitation current;...

Modeling and simulation of extra high voltage magnetically controlled shunt reactor based on PSCAD

“…Extra high voltage magnetically controlled shunt reactors (referred to as MCSR) [1][2][3], due to their flexible control and fast response time, can smoothly regulate the reactive power of the system [4][5], achieving true flexible transmission. It can also suppress power frequency and operating overvoltage, reduce line losses, and greatly improve the stability and safety of the system [6][7]. Therefore, MCSRs are important reactive power compensation devices in ultra-high voltage and ultra-high voltage power grids.…”

Modelling and Design of a Low-Level Turn-to-Turn Fault Protection Scheme for Extra-High Voltage Magnetically Controlled Shunt Reactor

“…The work presented for thyristor controlled transformer-type controllable shunt reactor (TCT-CSR) and MCSR in [20][21][22] up till now laid foundation for this research work, however, it also lacks the properties of identifying the faulty-phase, faulty-winding and achieving the lowest level of T2TF protection for MCSR. Therefore, the sole aim of this research work is to overcome the above deficiencies at lowest cost of changing the mechanical design or structural configurations, while achieving the targeted objectives through a low-level sensitive T2TF electrical protection scheme.…”