MV Switchgear Research Articles

A digital twin for MV switchgear condition monitoring data

A digital twin for MV switchgear condition monitoring data

Compact and Smart Outdoor Medium/Low Voltage Substation for Energy Communities

Energy transition toward smart grids with deep impact of renewables, energy storage systems, and electric vehicle charging stations will increasingly promote the establishment of energy communities that own portions of the electricity grid. The energy communities will consist of clusters of multiunit buildings and or single residential units aggregated sharing a common or multiple medium and low voltage (MV/LV) electrical substations. The size and impact of the location of these MV/LV substations can constitute a barrier especially for highly urbanized contexts where it is very complicated to provide technical spaces inside buildings for large technical systems like transformers, MV switchgear, etc. The idea of this work consists of developing a compact outdoor MV/LV substation to reduce the overall dimensions and to make the execution modularized to facilitate management and maintenance. Also an investigation of energy exchange between multiunit buildings, which are considered as the real energy community case study. The main objective for this case study is to minimize the operation cost of the system by maximizing the self-consumption.

Oversized Electrical Appliance Impacts on Condominium Energy Efficiency and Cost-Effectiveness Management: Experts’ Perspectives

A direct use approach incorporating a cost approach assumed that replacing oversized electrical appliances with those better fit to actual energy consumption can reduce energy consumption, optimizing capacities of the new appliances to the maximum while reducing electricity costs. This study aimed to verify the assumption that the size of appliances has impacts on energy consumption and cost effectiveness. A mixed-method approach included these instruments for data elicitations (i.e., a questionnaire, data records of 485 transformers, two assessments of condominium technical caretakers, and two in-depth interviews of electrical engineering experts). The findings revealed that most condominiums installed electric appliances that are too large for their actual energy usage, which lies between 5.4% and 7.1% of the capacity. This study therefore proposed a total cost reduction of 54% by downsizing these appliances (i.e., MV Switchgear 2 sets, dry type transformer 2 sets 80,000, LV Cable 10 m. (XLPE), main distribution board, Busduct (MDB-DB), generator (20% of Tr.), and generator installation). Even though this analysis is limited to Bangkok, Thailand, this case may contribute decision-making on electrical appliance selection at early stage of investment or to downsize the currently installed appliances for the more energy efficient and cost-effective management of condominiums around the world.

Upgrading internal arc resistance of existing substations

Existing MV/LV substations have been designed according to the applicable standards of the past. Since then, however, standards on internal arc resistance of substations have become stricter and safety awareness among grid operators has also increased. The replacement of electrical components in existing MV/LV substations, particularly exchanging the MV switchgear, can be a natural opportunity to assess and, if needed, upgrade the substation's internal arc resistance. In an attempt to avoid the assessment of each substation individually, this study investigates in general the need to upgrade internal arc resistance of MV/LV substations, based on worst-case situations. It appeared that in all considered cases a simple and affordable pressure relief hatch can solve any overpressure problems. Therefore, in case of replacement of the MV switchgear, this hatch can now be applied as a standard to ensure the internal arc resistance of the substation.

HOLISTIC VIEW FOR ENVIRONMENTALLY CONSCIOUS DESIGN OF MV SWITCHGEAR

The planet expects a return on investment. Environmental fighting is a subject where everyone can act. Even if it could become a matter for specialists to know whether individual or isolated action really contributes to the general interest, the only way to change is to act. This paper describes series of actions and how they were conduct for an environmentally conscious design of MV switchgear on standardization framework and on new offers.

SMART SWITCHGEARS WITH MV SENSORS - FIELD TESTS IN DISTRIBUTION GRID

This paper presents results from pilot project and field tests of Smart MV switchgear technology, which was installed into Czech urban MV distribution grid. Main goal of the project was to verify reliability of fault detection based on MV sensor technology, in comparison with conventional MV measurement transformers. Furthermore, several other reliability aspects of Smart MV Switchgears were tested, as this technology is infrequent in Czech distribution networks.

COMPACT GREEN MV GIS WITH ATMOSPHERIC AIR Innovation built on decades of heritage

This paper presents the SF6-free, MV GIS technology based on contained Natural Air at Atmospheric pressure, Electrical Field Control, and Vacuum Interrupters. This kind of switchgear and its predecessors exist for decades up till 24kV, and the technology is still evolving. SF6-free solutions for MV Switchgear are a key theme in the industry. The European Commission issued report C(2020) 6635, and - in anticipation of that stakeholders including T&D Europe gave their inputs. Various low- or non-greenhouse-gas solutions are being presented/launched based on fluorinated gases, or pressurized gas with natural substances. An advantageous SF6-free GIS technology has been on the market for a long time. It is safe and reliable, as compact as SF6-based-designs, uses atmospheric natural air (no procedures, no precautions, no End-of-Life management), and causes negligible effects at (unlikely) leakage. Electrical fields in the air at atmospheric pressure are controlled, and the airgaps already withstand the nominal rated voltage. In addition, shielding is applied to cope with over-voltages. Vacuum Interrupters have proven their reliability and enable a simple single-line with an upstream (no-load) Change-over-Switch, which is already very common in Secondary Switchgear. The GIS design comprises a Sealed Tank to protect the interior from humidity and pollution, and to contain the effects of internal arcs. Innovation continues, and next to a 630A design at 24kV-20kA, extension to 1250A up till 25kA is under development.

Partial Discharge Identification in MV Switchgear Using Scalogram Representations and Convolutional AutoEncoder

This work proposes a methodology to automate the recognition of Partial Discharges (PD) sources in Electrical Distribution Networks using a Deep Neural Network (DNN) model called Convolutional Autoencoder (CAE), which is able to automatically extract features from data to classify different sources. The database used to train the model is constructed with real defects commonly found in MV switchgear in service, and it also includes noise and interference signals that are present in these installations. PD sources consist of defective mountings, such as the loss of sealing cap of cable terminations, or an earth cable in contact with cable termination insulation. Four sources were replicated in a Smart Grid Laboratory and on-line measurement techniques were used to obtain the PD signal data. The Continuous Wavelet Transform (CWT) was applied to post-process the PD signal into a time-frequency image representation. The trained model predicts with high accuracy new data, demonstrating the effectiveness of the methodology to automate the recognition of different partial discharges and to differentiate them from noise and other interference sources.

Insulation strength of CF3I-CO2 gas mixtures as an alternative to SF6 in MV switch disconnectors

This paper evaluates the insulation performance of gas mixtures of trifluoroiodomethane and carbon dioxide (CF 3 I-CO 2 ) in a medium voltage switch disconnector. Practical testing compares the results of CF 3 I-CO 2 against SF 6 to examine whether CF 3 I-CO 2 could be a viable alternative when directly substituted into manufactured switch disconnectors in a purely insulating role. Positive standard lightning impulses were applied to the MV switchgear to determine whether CF 3 I-CO 2 can maintain the withstand voltage for which the switch disconnector is rated when filled with SF 6 . The results show that certain gas mixtures of CF 3 I-CO 2 , with a higher concentration of CF 3 I, could be used to insulate switch disconnectors against standard lightning impulses at the rated pressure.

Extreme weather has become the norm – is your MV switchgear ready?

The extreme weather we have been experiencing over the past half-decade seems becoming the new norm. Now without arguing about global warming and who is to blame, the fact of the matter is that most switchgear designers and experts agree that the environment has changed and is rapidly changing. Medium-voltage switchgear installed at industrial or commercial facilities could be exposed to these extreme environmental conditions. Switchgear components are made of varieties of materials and protective coatings according to operating area and service conditions. These switchgear components are subjected to deteriorating corrosion and ageing processes while effects of the high voltage to electrical insulation is mastered by appropriate classification of the switchgear according to the IEC/TS 62271-304 specification. The rate of which strongly depends on the presence of various gases, vapours, and particles and combinations thereof in the surrounding air. This study provides details on how to deal with unusual and extreme environmental conditions by carrying out some special tests that makes them reliable, fail-safe and trouble free operation throughout expected service life in addition to minimum maintenance requirement with less downtime.

Environmentally Conscious Technology for MV Switchgear

Environmentally Conscious Technology for MV Switchgear

Intelligent MV Switchgear as an Element of Smart Grid Network

Intelligent MV Switchgear as an Element of Smart Grid Network

The Smart Solution for the Prediction of Slowly Developing Electrical Faults in MV Switchgear Using Partial Discharge Measurements

An electrical fault in switchgear results in interruption of power supply, damage to equipment, and poses a hazard to personnel. This paper focuses on the detection of slowly developing faults leading to internal arc, using online monitoring technologies in medium-voltage switchgear. Unconventional radio-frequency (RF) techniques for discharge measurement are highly attractive but have not been widely applied in the industry due to their ineligibility to quantify actual discharge. On the basis of various benefits, a new application of a differential electric field ( D-dot) sensor for partial-discharge (PD) measurements has been introduced in this paper. The reliability of the sensor has been confirmed through comparison with a commercial high- frequency current transformer. An attempt has been made to quantify the apparent charge of online PD measurements. The energy of signal captured by the D-dot sensor has been compared with the apparent charge quantity calculated from current pulse measured by the conventional method. A second degree polynomial relation exists between the cumulative energy and apparent charge. It has been shown that when apparent charge is plotted against the cumulative energy of the RF signal for a number of pulses, defects can be separated on the basis of cluster positions within the scatter plot.

EVALUTION AND CALIBRATION OF MINIATURE CIRCUIT BREAKER

The purpose of this paper is to examine the significant developments in MV and LV switchgear technology over the last few decades and why they are only recently beginning to benefit the users. A recent development now has sufficient field experience to show how through innovative design it has been possible to vastly improve an auto-reclosing circuit breaker. The author believes that the same innovative ideas will soon be applied to all types of switchgear. Â The next generation of military switchgear is likely to be developed for the Electric Warship. Irrespective of which distribution supply is used the next generation of switchgear should benefit from the new technology. Calibration of Miniature Circuit Breaker takes a lot of time. Calibration is done to satisfy the International Standards so that all the MCBs are standardized. In this paper we concerned with decreasing this calibration time of MCBs whose rated current is less than or equal to 32 Amps. Calibration can be done by two methods, wiz, and Dual current and single current parameter method. This paper also deals with the decrease in the Calibration time and increase in Production efficiency by the use of later method which is a modification of the former one proposed and implemented here. This is done by employing faster motor for the calibration. Â A recent development now has sufficient field experience to show how through innovative design it has been possible to vastly improve an auto-reclosing circuit breaker. The author believes that the same innovative ideas will soon be applied to all types of switchgear.

Switchgear for 2000 and beyond

Customer values associated with medium-voltage switchgear have undergone a significant shift during the last decade. The privatisation of the electrical distribution industry in the UK has resulted in increased demands on MV switchgear in performance terms, including procurement and operating costs, ease of installation and reduced maintenance. Safety has remained of paramount importance and the environmental impact has become an essential element of designs.

Optimal design of autorecloser electromagnetic actuator

Following the successful development of a bistable electromagnetic switchgear actuator for driving vacuum interrupters in an autorecloser, several MV switchgear companies have begun to develop similar actuators for use in autoreclosers powered by primary lithium batteries. However, many of these actuators consume excessive energy in operation, adding undesirable battery cost to the equipment. A model is developed that enables these actuators to be optimised in energy terms, since it simulates the electrical, magnetic and mechanical effects seen by the actuator and their interactions. The model is a detailed lumped reluctance type. The lumped reluctances were defined after inspecting the results of the finite element analysis of a generic actuator. The model uses iteration routines to calculate the flux distribution within it and an improved stochastic optimal method to obtain an optimal design, in terms of magnet cost and operating energy usage. Simulated and test results are presented, and these show a close correlation.