Methods of Ferroresonance Mitigation in Voltage Transformers in a 30 kV Power Supply Network

Abstract

Inductive voltage transformers are the basic components of the switchgear equipment or electrical substations. This article presents problems related to their operation. Inductive voltage transformers were exposed to specific working conditions in the form of ferroresonance oscillations with the participation of measurement and protective transformers. The disadvantage and negative significance of the phenomenon contributed to the development of the most convenient elimination methods, which is the main goal and achievement of the publication. The analysis of the proposed solutions were carried out on a theoretical model of a 30 kV power network model created and run in the Electromagnetic Transients Program/Alternative Transients Program (EMTP/ATP). The article presents several results of computer simulations carried out together with their complete characteristics (phase voltage waveforms on the primary side of voltage transformers), which allowed us to indicate the disadvantages and advantages of the solutions developed, and choose the most favorable methods to eliminate nonlinear oscillations. In the article, we present an analysis of all aspects contributing to the solution to the problem. This has permitted an appropriate conclusion to be made indicating the advantage of the method based on the use of a damping resistor in the open delta circuit compared to other solutions. Current solutions are largely based on a product using active variation of the resistance of an open delta attached resistor. The concept in this paper is based on a fixed resistance value, which is a different approach to the problem. By using a switch, the resistor is only connected when a fault occurs. Thanks to this solution, the secondary winding of the open delta is not additionally loaded (despite the very high resistance) at all times during the operation of the power network, as is the case with the available solution.

A Differential Protection Scheme Based on Improved DTW Algorithm for Distribution Networks With Highly-Penetrated Distributed Generation

“…In [23][24][25], the positive sequence impedance, integral impedance, and high-frequency impedance are utilized as characteristic values for fault localization, thereby reducing the rigorous communication synchronization requirements. Impedance-based differential protection requires a voltage transformer, which is costly and generates ferromagnetic resonance [26]. Differential protection based on current amplitude is proposed to avoid voltage transformers [27][28][29], but it is not suited for networks with high penetration DG access.…”

Innovative Solid-State Ferroresonance-Suppressing Circuit for Voltage Transformer Protection in Wind Generation Systems

“…approaches, introducing damping to the circuit through resistance insertion was proposed in [10]. However, this technique is also slow because of the mechanical delays of resistance insertion.…”

“…The inherent properties of the capacitances and inductances involved in ferroresonance, along with the frequency, magnitude of the supply voltage, and initial conditions, are crucial parameters that influence the occurrence of ferroresonance [9]. This phenomenon can be initiated by several transient events, including short circuit faults, load rejection, the (de-)energization of transformers, and circuit breaker switching [10,11]. It is important to stress that ferroresonance can be described through nonlinear differential equations, which can be analyzed utilizing various methods, including the harmonics balance method, phase plane diagram, and bifurcation theory [12,13].…”

“…Moreover, VT ferroresonance is mostly inflicted by the stray capacitance of an already opened circuit breaker. Regarding ferroresonance energy suppression approaches, introducing damping to the circuit through resistance insertion was proposed in [10]. However, this technique is also slow because of the mechanical delays of resistance insertion.…”

Dynamic Analysis and Suppression Strategy Research on a Novel Fractional-Order Ferroresonance System

“…Against this background, several methods to overcome the limitations of ferroresonance suppression associated with chaos control theory have been developed for power transformers [20,21]. To date, several methods and measures have emerged in ferroresonance elimination applications, such as the nonlinear feedback control method [22], the proportional integral (PI) control method [23], and the current-limiting method based on fault current limiter (FCL) [24]. Several scholars have generally been concerned about the hot issue of ferroresonance overvoltage mitigation in power systems.…”