A Reserve Planning Method of Transformer Group based on Markov Reliability Model

In view of the current situation that the load difference is not considered in the existing research on public standby transformer, the reliability Markov model and public standby planning model of distribution transformer unit based on public standby mode are proposed. When the transformer fails, the standby transformer is preferred to replace the faulty transformer. The power failure time of the user is shortened from the transformer maintenance time to the standby installation and operation time. The state transition rate is the installation and operation rate of the standby transformer, and the replaced faulty transformer is converted to the standby transformer in the unavailable state. This paper applies the scheme decision analysis method to the field of engineering control, and applies the combination of the compound matter element analysis and the subjective and objective weight to the quantitative calculation of correlation entropy. This method solves the current situation that transformer faults are difficult to measure and calculate quantitatively, and it can accurately predict the healthy development trend of transformers, which has a good guiding value for the use and maintenance of transformers. At the same time, the public standby measures of distribution transformer can better solve the problem of long transformer fault repair time with a small amount of capital investment, effectively shorten the recovery time of fault outage and reduce the impact of transformer fault. The standby measures of distribution transformer have an obvious impact on the reliability of distribution system.

A Comparison Between Half and Full Fins at Nanofluids in Transformers

Power transformers characterize the biggest section of capital investment within the distribution substations as well as transmission. Additionally, outages of those transformers have a substantial economic influence on the functioning of an electrical network due to the fact that the power transformers are one of the utmost overpriced constituents in an electricity structure. A suggested thermal model for a distribution transformer is investigated. The temperature distribution in the three-phase transformer (250 KVA 11/.416 KV core type, mineral oil) was obtained using “COMSOL PROGRAM” after a 3D simulation utilizing a transient analysis in light of the Finite Element Method (FEM). Meanwhile, the suggested model is being used to examine the impacts of different types of oil on HOST. To test the effect of nanoparticles on heat transfer process, the insulation oil was changed with Nanofluids and hybrid nanofluids; For present work, can be concluded when add nanofluids (Al2O3, CuO, SiC) for oil of transformer under different concentration ratio (0.3,0.5,0.8,1,1.2,1.4 % wt) and add hybrid nanofluids (oil+ Al2O3+CuO), (oil+ Al2O3+SiC), (oil+ SiC +CuO) at different concentration ratio (1,1.2,1.4 % wt). The concentration of nanofluids show a direct influence on the temperature reduction for the studied cases. Finally it can be said, the proposed model was succeeded in simulating the distribution transformer, which is in good agreement with the experimental tests adopted for this work, and it could be used as a design tool with assist of COMSOL Multiphysics Package. The present model successfully accomplished for expecting the temperature distribution at any locations in the transformer when compared with practical measurement.

Optimizing the effect of charging electric vehicles on distribution transformer using demand side management

This paper mainly aims to present the demand side management (DSM) of electric vehicles (EVs) by considering distribution transformer capacity at a residential area. The objective functions are formulated to obtain charging schedule for individual owner by i) minimizing the load variance and ii) price indicated charging mechanism. Both the objective functions profit the owner in the following ways: i) fulfilling their needs, ii) minimizing overall charging cost, iii) lessening the peak load, and iv) avoiding the overloading of distribution transformer. The proposed objective functions were worked on a residential area with 8 houses each house with an EV connected to a 20 kVA distribution transformer. The formulations were tested in LINGO platform optimization modeling software for linear, nonlinear, and integer programming. The results obtained were compared which gives good insight of EV load scheduling without actual price prediction.

The Local Ordered Charging Strategy of Electric Vehicles Based on Energy Routers under Three-Phase Balance of Residential Fields

With the popularization of electric private cars and the increase of charging facilities in residential areas, disorderly charging will affect the power supply efficiency of their distribution transformers and the quality of electricity used by users in residential areas. In severe cases, it may even cause vibration of the power grid, causing serious three-phase imbalance problems such as single-phase burnout of transformers or insulation breakdown of household appliances. This paper analyzes the influencing factors of the unbalanced operation of each phase of the distribution transformer and the electrical load characteristics of typical residential areas. Based on the photovoltaic output of the station area, the charging and discharging capacity of the energy storage system, and the orderly charging plan of residential electric vehicles, a local orderly charging strategy for electric vehicles based on energy routers under the three-phase balance of the residential area is proposed. This strategy can realize the three-phase balance control of the distribution transformer. The effectiveness of the method is verified by a typical scenario example. The control method is changed to minimize the three-phase imbalance in residential areas and improve the low utilization rate of the distribution network and the comprehensive utilization efficiency of adjustable resources in residential areas.