Ferroresonance Phenomenon Research Articles

Ferroresonance phenomena in power systems

It is a known fact that the world's dependence on electrical energy is increasing day by day. The fact that electrical energy has some advantages over other types of energy, the increasing world population and changing living conditions can be considered among the reasons for this increase. This increase in dependence on electrical energy can be met by expanding existing facilities and establishing new facilities. In these studies, the transmission of electrical energy from the place where it is produced to the place where it is consumed poses important problems as the system expands. Some work is required to eliminate these technical and economic problems and to ensure stable operation of the system. These are problems that were not considered beforehand as the system grew. One of these problems is the ferroresonance phenomenon that occurs at the fundamental frequency due to the nonlinear magnetization characteristics of transformers. Ferroresonance is a resonance phenomenon that occurs in an electrical circuit containing an iron-core self-coil as a nonlinear element. This resonance manifests itself with sudden oscillations in the output size of the system caused by a small change in the amplitude or frequency of a magnitude applied to the input of the system. High voltage transmission lines are double-circuit lines that share the same pole. In special cases such as maintenance or malfunction of such a transmission system, one of the lines can be disconnected from the system and continue energy transmission with the other line. In the high voltage transmission line, the system may oscillate due to the stored energy in the magnetic field of the transformer inductance on the disabled line and the electric field of the line capacity. This oscillation disappears after a certain period of time due to iron losses and other circuit losses. When these losses are covered by the other transmission line, permanent oscillations and over voltages may occur at the transformer terminals. All these events are the negative effects of ferroresonance on transmission systems. In the energy transmission system, ferroresonance phenomenon occurs. Over voltages may occur in case of idle power transformers in star point/isolated networks. In medium voltage networks, ferroresonance occurs due to the melting of a fuse, the opening and closing of voltage transformers with one pole, and the dissymmetry that occurs as a result of a connection process. These negative effects caused by ferroresonance in the energy transmission power system are discussed in detail within the subject of this study.

Ways to prevent ferroresonance phenomena in a network with an isolated neutral

Ways to prevent ferroresonance phenomena in a network with an isolated neutral

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

Ferroresonance is characterized by overvoltage and irregular operation in power systems, which can greatly endanger system equipment. Mechanism analysis of the ferroresonance phenomenon depends mainly on model accuracy. Due to the fractional-order characteristics of capacitance and inductance, fractional-order models are more universal and accurate than integer-order models. A typical 110 kV ferroresonance model is first established. The influence of the excitation amplitude on the dynamic behavior is analyzed. The fractional-order ferroresonance model is then introduced, and the effects of the fractional order and flux-chain order on the system’s motion state are studied via bifurcation diagrams and phase portraits. In order to suppress the nonlinear dynamic behavior of fractional-order ferroresonance systems, a novel fractional-order fast terminal sliding mode control method based on finite-time theory and the frequency distributed model is proposed. A new fractional-order sliding mode surface and control law using a saturation function are developed. A robust fractional-order sliding mode controller could achieve finite-time stabilization and tracking despite model uncertainties and external disturbances. Compared with conventional sliding mode methods, the simulation results highlight the effectiveness and superiority. The research provides a theoretical basis for ferroresonant analysis and suppression in large-scale interconnected power grids.

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

Ferroresonance, as an undesirable disturbance, leads to significant overvoltage and distorted waveforms. This phenomenon can be highly damaging to voltage transformers and other parallel-connected equipment and can entail catastrophic consequences. This paper aims to design and study a solid-state ferroresonance-suppressing circuit (SSFSC) to protect voltage transformers (VTs) together with other parallel-connected equipment in wind generation systems from the adverse effects of the ferroresonance phenomenon. The proposed structure consists of low-voltage circuits, including power IGBTs. The excellent performance of the proposed SSFSC in suppressing ferroresonance overvoltage in wind generation VTs has been authenticated by analyses conducted utilizing a wind generation system model. In order to validate the performance of the proposed SSFSC, detailed analytical studies and time-domain simulations have been carried out employing a MATLAB/Simulink environment. The results verify that the proposed SSFSC can effectively suppress ferroresonance phenomena in VTs and mitigate their accompanying overvoltages with a high operational speed.

Effect of the drop out fuse connection scheme on the overvoltage and the surge arrester in a distribution system

Overvoltage is a critical problem of Thailand’ distribution system. The electrical protection device in the distribution system needs to be able to support this level of overvoltage. In the distribution system connecting the Chachoengsao2 substation and the Bang Khla substation, the overvoltage from a ferro resonance phenomenon affects the surge arrester directly. This research studies the effect of the drop-out fuse connection scheme on the voltage and surge arrester using the RMS/EMT Simulation mode in the DIgSILENT program. Normally, the surge arrester withstands a voltage of 1.9 p.u. of the phase voltage. If the overvoltage in the distribution system is higher than the voltage that the surge arrester can withstand, the surge arrester can be damaged. Therefore, it is necessary to study and analyze the drop out fuse insertion pattern that affects the overvoltage in the distribution system to understand the causes of overvoltage problems and their effects on each type of electrical protective equipment.

Ferroresonance mitigation for the unconventional rural electrification system

This paper presents a solution to the observed ferroresonance (FRR) phenomenon for both energization switching and load shedding conditions in an unconventional rural electrification system. The energy is extracted from the electric field surrounding an extrahigh voltage transmission line. Ferroresonance occurs in the power transformers of the distribution substation, and the existing solution cannot be directly applied. The mitigation method consists of the insertion of a shunt resistor when the FRR starts. The robustness of the method is shown in a time-domain simulation implemented in PSCAD/EMTDC.

Diagnosis of Chaotic Ferroresonance Phenomena Using Deep Learning

Ferroresonance is a non-linear and dangerous resonance phenomenon that can affect power networks and damage electrical equipment. The ferroresonance phenomenon is examined by dividing it into classes, with chaotic ferroresonance being the most dangerous type that causes overvoltage’s. Detecting chaotic ferroresonance in a short period of time is of great importance in terms of taking measures and reducing equipment damage. In this study, we explored the application of deep convolutional neural networks (DCNNs) for the identification and classification of chaotic ferroresonance phenomena. Two pre-trained AlexNet models were adapted using transfer learning to perform these tasks. The first model was utilized to identify chaotic ferroresonance, while the second was employed to distinguish between different subtypes of chaotic ferroresonance by dividing voltage curve graphs into different periods and shapes. The training and testing of both DCNN models were conducted using snapshot images extracted from the voltage curves of all phase voltages. The results of the experiments showed high accuracy in both the identification and classification of chaotic ferroresonance phenomena.

Optimization-Based Mitigation Techniques of the Temporary Overvoltage in Large Offshore Wind Farm

Overvoltage transient is the major danger facing large offshore wind farms, as it may lead to a complete failure of the system components. A 150 MW offshore wind farm was modeled using the ATP-EMTP package to analyze the effect of the temporary overvoltage resulting from de-energization conditions, and the ferro resonance phenomenon resulting from the asymmetric opening of circuit breaker pole(s). The results showed that the best scenario to shut down such a system from the grid with minimum values of temporary overvoltage is to disconnect it, feeder, by a feeder. The stuck of one or more poles during the opening operation of the circuit breaker is a dangerous phenomenon, as it induces a high overvoltage value, which lasts for a long time causing more electric stress on the sensitive components of the system. The use of the Pre-Insertion Resistor PIR was recommended as a mitigation technique for the temporary overvoltage in large offshore wind farms, as it proves a significant reduction in the overvoltage values reaches to 79.44 % compared to surge arrester and shunt reactor which reduce the over voltage by 68.33%, 66.29% respectively. The genetic algorithm was used to find the optimum value of the PIR and shunt reactor that leads to the minimum TOV. The optimum value of PIR which was recorded is equal to 57.352 Ohm, which leads to more reduction in the overvoltage value by 9.67%. Also, the optimum values of the resistor and inductor of the shunt reactor were found to be 11.238 Ohms and 37.246 mH which leads to more reduction in the overvoltage value by 21.97% compared to the reduction without optimization.

Analiza mogućnosti nastanka ferorezonanse u izolovanoj 6 kV mreži

Ferroresonance is a complex nonlinear electrical phenomenon that can cause significant dielectric and thermal stresses in power equipment, leading to potential faults, equipment damage, power supply interruptions, etc. Three-phase networks with isolated neutral point and single-phase isolated inductive voltage transformers are susceptible to ferroresonance, caused by the interaction of the transformer's nonlinear inductances and zero sequence capacitance of power network. The paper analyzes the possibility of ferroresonance occurrence in a real 6 kV power network, with an isolated neutral point, using the electromagnetic transients program ATP/EMTP. A detailed network model is developed, taking into account the nonlinearity of voltage and power transformers, which is utilized to analyze various configurations, switching operations, and faults in the network that could trigger ferroresonance. It is shown that, under certain circumstances, ferroresonance can occur, with faults clearing being the most common initiators of ferroresonance. The efficiency of different measures to suppress ferroresonance is also analyzed. The impact of the resistance values of voltage transformer's open delta winding dumping resistor on the suppression of ferroresonance occurrence, is considered.

Elimination of ferroresonance in the distribution zone by high ohmic reactor-shunt limiter

Electrical network components catastrophically fail as a result of aberrant system oscillations. Also, consequently leads to saturation in the ferromagnetic core elements. These factors induce distortions in the voltage and current waveforms as well as a large rise in voltage or current. This paper presents the role of distributed generation (DG) in contributing to ferroresonance investigation reduction in the distribution sector. A high ohmic reactor-shunt limiter (HOR-SL) is introduced as a novel technique based on a negative sequence component to mitigate ferroresonance. The proposed HOR-SL reduces the ferroresonance in distribution system (DS) by no more than 10.5 msec. A PSCAD/EMTDC software is used to model the ferroresonance phenomenon. The simulation results strongly show the effectiveness of using the proposed HOR-SL for limiting ferroresonant oscillations and creating stable orbit in the distribution sector. Case studies verified the effectiveness of the proposed technique in mitigating ferroresonance oscillations and keeping the security of the distribution zone.

Modeling of Ferro-Resonance Phenomenon with Saturation of Grid-Connected Transformer in ESS

Modeling of Ferro-Resonance Phenomenon with Saturation of Grid-Connected Transformer in ESS

The investigation of ferro resonance voltage fluctuation considering load types and damping factors

Abstract Background and Objectives: The occurrence of ferro resonance is a very complex phenomenon in power systems. In circuits including inductors and capacitors, if the value of zc = zl becomes, an intensification or resonance state is created in the circuit. In circuits and networks that have saturated inductors, nonlinear resonance or ferro resonance is created, Ferro resonance is a nonlinear resonance phenomenon that occurs between the network capacitor and the nonlinear inductance of the transformer during saturation. Ferro resonance at the main frequency and higher frequencies cause insulation problems and at low frequencies causes thermal problems. In the event of this phenomenon, the voltage range increases to a considerable extent and may also be distorted, which due to the structure of the winding connections in transformers can cause damage to electrical installations. Methods: In this paper, we study and simulate the phenomenon of ferro resonance and provide solutions such as using high resistance on the primary side of the transformer and the combination of resistors and inductors on the secondary side of the transformer to damp the ferro resonance in MATLAB software. Furthermore, the utilization of surge arresters is discussed in detail. Results: It is illuminated that utilization of suggested approaches has an acceptable reduction rate on the damping of ferro resonance fluctuations. Especially when using resistor and inductor simultaneously the fluctuations reduce and ferro resonance is damped immediately. Conclusion: It is important to pay attention to the transformer and the amount of capacitors in transmission lines, especially cable lines. Furthermore, asymmetric switching is another important factor. High resistance can reduce fluctuations but causes power losses in the circuit but using Resistance and inductor structure are able to create acceptable damping and reduce fluctuations without loss problems. The presence of a surge arrester can also reduce the overvoltage caused by ferro resonance to an appropriate level.

A Comprehensive Study Approach for Evaluation of Resonance and Ferro-Resonance in HV Substations A Case Study: Khuzestan Regional Electric Company

Resonance and ferroresonance in power systems are categorized as two destructive phenomena especially in HV networks which their occurrence are being initiated in consequence of a power system event. Also, Ferroresonance phenomenon may be initiated by non-power system event such as lightning strike. Hence, the study of resonance and ferroresonance requires an exhaustive evaluation of possible network events in different network configurations. In each event, the analysis of network voltages is conducted based on identified allowable limits by IEEE 519 standard as an evaluation critera. In this paper, a novel comprehensive study approach is proposed for study of ferroresonance phenomena in power networks. The proposed approach comprises different steps including substation equipment modeling, EMT simulation of the probable switching events, evaluation of correspondence results, and finally detecting the probable ferroresonance occurrence. Furthermore, a novel approach for resonance study is also presented. Voltage and current limits are implemented to define an impedance criteria for performing resonance evaluation of network buses. Findings – The proposed method is implemented for study of resonance and ferroresonance in all HV substations of the Khuzestan regional electricity network. By performing the proposed evaluations, the probable condition which may lead to resonance and ferroresonance occurrence are identified. The results are highly valuable for network operators in prevention of unintended overvoltages occurrence.

Forecasting of voltage disturbances at the beginning of ferroresonance phenomena in power systems using by a new approach of long-short term memory (LSTM): LSTM for Ferroresonance in power systems

Ferroresonance is an unexpected, continuous, and undesirable event that causes excessive growth and distortion in the voltage and current waveform, whose cause is unknown and suddenly develops in power systems. To take precautions against the ferroresonance phenomenon, it is necessary to be able to predict how the distortions in the ferroresonance voltage will continue. Today, the ferroresonance problem has not been fully solved yet and more scientific studies are still needed. In this study, a new approach of an LSTM network has been developed that predicts the irregular and excessively large-amplitude continuing behavioral disturbances of the phase voltage in a real electrical power network exposed to ferroresonance. As a result of the study, the ferroresonance-voltage continuing in distorted waveform was estimated with an error of 0.0346 according to the Mean Absolute Percent Error (MAPE). The training data used in the study is only about 5% of all predicted ferroresonance voltage data. The successful estimation of 95% of the Ferreroresonance voltage using only about 5%, proves the success of the LSTM model applied with a new approach for the study.

ФЕРРОРЕЗОНАНСНЫЕ ПРОЦЕССЫ В СИСТЕМАХ ЭЛЕКТРОСНАБЖЕНИЯ С РАСПРЕДЕЛЕННОЙ ГЕНЕРАЦИЕЙ

Relevance The article is devoted to the study of the possibility of occurrence of ferroresonant processes in power supply systems with distributed generation. Ferroresonant processes cause overvoltages in electrical installations and lead to their failure. In backbone and distribution networks without distributed generation facilities, the phenomenon of ferroresonance has been studied quite deeply, effective hardware and operational measures have been developed to prevent the occurrence of ferroresonance surges in electrical installations. However, the issue of the occurrence of ferroresonant processes in power supply systems with distributed generation, which is a promising direction in the development of the energy sector, seems to be little studied. Aim of research The main aim of the research is to investigate circuit-mode conditions for the occurrence of ferroresonant processes in power supply systems with distributed generation. Research methods To study the circuit-mode conditions for the occurrence of ferroresonant processes in power supply systems with distributed generation, the main provisions of the theory of electrical complexes and systems, the theory of nonlinear electrical circuits, and the principles of controlling objects of electrical complexes and industrial systems were used. Results The circuit-mode conditions for the occurrence of ferroresonant processes in power supply systems with distributed generation are studied. The power supply system of a HF radio center, containing a power plant with a lower installed power or corresponding to the maximum power consumption of the load, was chosen as the object of study. The features of the scheme-mode conditions for the occurrence of ferroresonant processes under conditions of distributed generation are as follows. Due to the insignificant remoteness of distributed generation facilities and consumers, additional opportunities arise for subharmonic ferroresonant processes. When a generating plant is connected to low-voltage busbars, conditions are created for the occurrence of a ferroresonant process involving low-voltage windings of power transformers. The low dynamic stability of generating installations of distributed generation facilities based on synchronous generators reduces the likelihood and duration of ferroresonant processes in the event of phase wire breaks and short circuits on the power line. Generating plants connected via grid inverters have a limited output current and can be turned off by emergency automatics in the event of an emergency operation of the grid, which, as a rule, precedes the appearance of ferroresonant overvoltages in electrical installations. Thus, in power districts with distributed generation facilities, the circuit-mode conditions for the occurrence of ferroresonant processes, known in the centralized power supply system, undergo changes, and it is also possible to form new ferroresonant oscillatory circuits. Keywords: distributed generation, ferroresonant process, power supply system, oscillatory circuit, generating plant, relay protection and automation devices Acknoledgements: The work was carried out under the state order of the Omsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences (project state registration number 122011200349-3).

Effect of GIC Neutral Blocking Devices (NBDs) on Power Network Ferroresonance in Malaysia

Geomagnetic disturbance (GMD) arises during space weather and solar activity can result in geomagnetically induced current (GIC) flow in the grounded power transformers in the power network. This GIC may cause half-cycle saturation of transformers and lead to severe damage or blackout. To block the GIC flow into the power transformers, the neutral blocking devices (NBDs) based on capacitor banks are often installed in the neutral ground paths of transformers to mitigate the GIC. However, the high voltage (HV) can build up across these capacitors during ground faults and may cause a ferroresonance phenomenon in the power network. This phenomenon generates high voltages/currents in the transformer windings and results in transformer failure. This work investigates the effect of connected NBDs to the power transformers on the potential power network ferroresonance in Peninsular Malaysia. The complete analysis was carried out using the Power System Computer-Aided Design for Electromagnetic Transients including Direct Current (PSCAD/EMTDC) software. These transformers were selected in the power network due to the sensitivity of their locations to GMD events. The NBD systems were tested under different working conditions. The simulation results found that the metal oxide varistors (MOVs) arresters in NBDs fault protection mode effectively clamped ferroresonance overvoltages below the protection level under faulty conditions. Also, the results showed that GIC protection modes with 1 ω and 3180 μF in the mitigation systems had the lowest ferroresonance overvoltages in the neutrals of the transformers under faulty conditions. Based on the results, the recommendations were provided to the local power utility which will help to improve the reliability of the power supply to the consumers.

ФЕРРОРЕЗОНАНСНЫЕ ПЕРЕНАПРЯЖЕНИЯ В ЭЛЕКТРОУСТАНОВКАХ 6–220 кВ: ТЕОРИЯ И РЕЗУЛЬТАТЫ ЭКСПЕРИМЕНТАЛЬНЫХ ИССЛЕДОВАНИЙ

Relevance The article is devoted to the systematization and generalization of theoretical and experimental studies of ferroresonance overvoltages in electrical installations 6–220 kV. The need to study this issue is associated with the active introduction of distributed generation facilities into distribution networks, as well as medium and low voltage networks. In power districts with distributed generation facilities, the settings and operation algorithm of relay protection and automation devices differ from the traditional ones used in centralized power supply. The generation parameters and the nature of electromechanical transients also differ, which is caused by the low dynamic stability of generating plants based on synchronous generation and the use of network inverters with energy storage in electronic generation. Thus, due to significant differences in the parameters of the network operation mode with and without distributed generation objects, it is necessary to revise many well-known technical problems, including the issue of ferroresonant processes. Electrical installations of 6–220 kV were chosen as the object of research, since the concept of distributed generation does not imply backbone networks, and the maximum installed power of an individual facility is limited by 25 MW. Aim of Research Aim of research is to systematize and summarize the theoretical and experimental studies of ferroresonance overvoltages in electrical installations 6–220 kV. Research methods To study the circuit-mode conditions for the occurrence of ferroresonant processes in electrical installations of 6–220 kV, an analysis of foreign and domestic publications, standards was carried out, and the theoretical foundations of electrical engineering and the theory of nonlinear electrical circuits were used. Results The physical essence of the phenomenon of ferroresonance, the conditions for the occurrence of ferroresonant processes and measures to prevent them in medium and high voltage networks, experimental studies of ferroresonant processes are considered. The ferroresonant process consists in compensating the inductive and capacitive resistances in the oscillatory circuit with a saturated inductance core. There are various modes of ferroresonance, which are determined by the initial conditions: fundamental, subharmonic, aperiodic and chaotic. A prerequisite for the occurrence of a ferroresonant process is the power of the power source sufficient to saturate the inductance core. Non-linear inductance that can participate in the formation of an oscillatory circuit are voltage transformers, power transformers, shunt reactors. The capacity of the circuit can be a power line, a busbar system, a capacitor bank, shunt capacitors of switches. Hardware and operational measures to protect against ferroresonant processes in electrical installations are aimed at changing the capacitance or inductance of network elements that may participate in the formation of a ferroresonant oscillatory circuit, preventing the formation of such a circuit or reducing its quality factor. The results of experimental studies of ferroresonant processes do not contradict the guidelines for protection against resonant voltage increases in electrical installations. Keywords: ferroresonance overvoltages, distributed generation, ferroresonant process, electrical installation, busbar system, high-voltage switch, non-linear inductance

Eliminating VT uncertainties in modeling ferroresonance phenomena caused by single phase-to-ground faults in isolated neutral network

It is commonly recognized that correct transformer model (particularly topological one) is a key element for any ferroresonance simulations. This paper represents a line of reasoning by which a reliable model of a voltage transformer (VT) can be constructed given substantial uncertainties in its parameters and characteristics. Starting with catalog data for electric steels and typical leakage inductances of 6-kV VTs, a model of an isolated neutral network with three inductive VTs is initially fitted to reproduce in detail its ferroresonant behavior for a chosen network capacitance. Then, validity of the network model is verified by accurate predictions of ferroresonance processes for all other capacitance values available and thus different ferroresonance modes recorded during full-scale factory tests. Possibilities to simplify the VT model by neglecting dynamic, and then entire core losses and hysteresis are also shown.

Исследование особенностей явления феррорезонанса в электрических сетях 6–35 кВ на основе математического моделирования

Objective: To analyze the existing circuitry solutions in order to prevent ferroresonance phenomena. Simulate the phenomenon of ferroresonance in MATLAB Simulink to reduce its negative impact on electrical systems. Methods: The applied methods are based on the analysis, synthesis and mathe- matical modeling of electrical systems in the event of ferroresonance. Results: The necessity of im- proving circuitry solutions to prevent ferroresonance phenomena is shown. The possibility of using the modeling of ferroresonance phenomena in the MATLAB Simulink environment is shown in order to reduce the negative impact of ferroresonance and increase the reliability of the operation of elec- trical systems. Practical importance: When simulating in the MATLAB Simulink environment, you can get results that will allow you to develop measures to reduce the negative impact of ferroresonance on electrical systems.

ASPECTE CALITATIVE ȘI CANTITATIVE ALE FENOMENUL DE FEROREZONANȚĂ ÎN INSTALAȚIILE ELECTRICE DE JOASĂ TENSIUNE

The phenomenon of ferroresonance is generated by the interaction between nonlinear magnetic devices and capacitive elements in an electrical installation in which losses are reduced and which are constantly supplied by at least one energy source. Feroresonance is manifested by the appearance of overvoltages and overcurrents in the installation with strongly distorted waveforms. Also, the phenomenon is accompanied by other disturbances of the quality of electricity (voltage fluctuations, asymmetries, noise, etc.), which propagate in the network affecting the proper functioning of the entire installation. In addition, unlike linear resonance, ferroresonance allows the manifestation of several stable states (modes) for the same parameters of the network, these being imposed by the initial conditions in the installation and the moment of occurrence of the phenomenon. Thus, the vulnerability to low resonance of a low voltage installation has become an indicator of electricity quality. This paper presents a procedure for calculating and investigating this phenomenon based on the analysis of numerical solutions of systems of differential equations (nonlinear and non-autonomous), which models the transient phenomena that initiate the appearance of ferroresonance (usually switching processes). Also, modern means of investigation are used (3D visualizations in the phase plan or Poincaré diagrams), imposed by the difficulty of the quantitative analysis both in dynamic regime and in stationary regime of ferroresonance. In addition, methods and procedures are proposed to mitigate the effects of the ferroresonance phenomenon on equipment or network elements in electrical distribution installations.