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In this manuscript, a hybrid approach for optimal detection and classification of fault on load tap changer of power transformer is presented. The proposed hybrid approach is the Tasmanian Devil Optimization, Spike Neural Network and commonly called to as the TDO-SNN method. The major objective of the proposed approach is to minimizing the error and enhances the accuracy, safety, and efficiency of power transformer operation within electrical power systems. Classification of transformer faults is applied in two phases with the ultimate goal of SNN detection. In various situations, thenormalSNN first phase is used to detect the healthy or unhealthy state of the transformer. The second phase SNN process uses TDO from the perspective of minimum error objective function. Classifying the transformers' ill state in order to identify the proper faults for protection is the 2nd stage of the SNN. At the first stage, the TDO-SNN method plays an estimate process to protect the transformer and detect the fault in the transformer. The TDO-SNN technique reduces the problem of transformer fault deduction and classification and the accuracy of the system is high. Then, the model is executed in MATLAB platform and the implementation is designed with current procedures. • Hybrid Approach for Optimal Detection. • Hybrid Approach is the Tasmanian Devil Optimization. • Spike Neural Network. • Transformer Fault Deduction. [ABSTRACT FROM AUTHOR]

With the development of society, the demand for electric energy is growing day by day. However, the energy centers and load centers are geographically distributed in a reverse direction, so the power supply and demand are unbalanced. High voltage transmission lines are characterized by long distance and large capacity, and the power flow problems are increasingly prominent. In order to flexibly adjust the line power flow, improve the comprehensive utilization of grid assets, and improve the transmission capacity of the system, this paper analyzes the principle of double core symmetrical phase-shift transformer (DS-PST) and the application of power flow regulation. Firstly, the basic principle of phase shifting transformer is analyzed in detail, and the equivalent mathematical model of DS-PST and the calculation of main parameters are derived. Impedance coefficient and excitation coefficient are introduced to modify the parameter design of DS-PST. Then, an electromagnetic simulation model is established to verify the effectiveness of the design method. Finally, a system simulation model is built to verify the power flow regulation effect of DS-PST by taking 500 kV UHV power grid and IEEE standard multi-node system as examples. DS-PST can transfer the active power transmitted by the lines with high load rate to the lines with low load rate, which makes the power flow distribution of the system more balanced and effectively improves the transmission capacity of the power system.

The Modular multilevel converters (MMCs) have excellent performance when operated with high modulation index such as the case of gird-connected converters in high voltage direct current (HVDC) system. Reliable and fault tolerant operation (FTO) of the system is very important in HVDC. A novel FTO algorithm under sub module failure without using any additional redundant SMs is proposed. In the proposed method, the direct current bus voltage control and on-load tap changer (OLTC) control strategy are combined for interruption free operation of the system without any additional voltage stress on switching devices and performance degradation of the system during fault. The analytical details of the normal as well as FTO operation are given. The proposed FTO strategy is verified through simulation and also experimentally using a prototype. The simulation and experimental results are presented.

This paper studies the application of distributed and centralized solutions for voltage control in low voltage (LV) grids with high photovoltaic (PV) penetration. In traditional LV grids, the coordination of distributed PV converters and a centralized device would require massive investments in new communication and control infrastructures. The alternative of exploiting distributed PV converters for voltage control is discussed, showing that it can help to stabilize the voltage in the grid connection points also without coordination between them and/or with a centralized unit. The goal of this paper is to investigate how the setup of the voltage controllers inside PV inverters affects the operation of these controllers taking into account the limits for reactive power injection. In addition, the interaction of distributed PV converters with centralized devices (static var compensators and on load tap changers) is analyzed to assess whether additional benefits may come in these cases. [ABSTRACT FROM AUTHOR]

There is increasing interest in the evaluation of the capability of power-electronic-interfaced distributed generators (DGs) connected to weak medium-voltage (MV) feeders, to provide ancillary services. Classic simulations using simplified DG models have their limitations and may prove insufficient due to the complexity of adequate modeling of power electronic interfaces. Moreover, conventional testing does not allow the investigation of the real generator with the distribution system interactions. Therefore, a scaled-down physical DG (i.e., inverter and dc source) with exactly the same functionalities can be used to evaluate the network integration of the actual DG, by means of power hardware-in-the-loop (PHIL) testing. In this paper, suitable scaling of the power rating and voltage level of the hardware is performed, and an interfacing approach is proposed that achieves stability of simulations without compromising accuracy. The PHIL tests successfully demonstrate potential problems in the coordination of the on-load tap changer controlling the MV feeder with the voltage controller of the DG, such as recurring tap changes, increased reactive power flows, and opposing actions. Moreover, recurring oscillations of the voltage controller of the hardware model are observed at certain system configurations. These inverter control instabilities, which are not visible in purely digital simulations, demonstrate the added value of employing PHIL testing for current and future power system analysis and testing. [ABSTRACT FROM PUBLISHER]

HTS transformers which have been developed until now had only fundamental structures. Among the auxiliary functions of conventional transformers, voltage regulating is the most important one. For the voltage regulation, conventional transformers are equipped with on load tap changers (OLTCs). In this paper, we investigate the possibility of the HTS transformer with OLTC. For the case study, we designed a single phase 33 MVA HTS transformer with OLTC. It is one of three individual HTS transformers which composes a 3 phase, 100 MVA transformer. It is expected to substitute for a 3 phase, 60 MVA conventional transformer in Korea. The parameters of an HTS transformer are varied due to the gap length between primary and secondary windings. The length was decided for the transformer to have the impedance of 12%. Its size was limited to the one of the conventional transformer. The characteristics of the HTS transformer were analysed in both case of having OLTC and not. [ABSTRACT FROM AUTHOR]