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Owing to the economic, social, and political problems in the expansion of transmission infrastructure, novel transmission topologies are in demand to efficiently utilize the existing infrastructure. On the other hand, there is a tremendous increase in wind power generation around the globe. One of the main challenges hindering the penetration of large-scale wind power generation is the network congestion due to limited network capacity. To address these two issues, this study develops a co-optimized optimal transmission switching (OTS) and dynamic line rating (DLR) model to optimize system resources by mitigating network congestion and maximizing wind power accommodation. This new concept of exploiting the inherent flexibility in transmission network is named as flexible transmission dynamic line rating (FTDLR), which deploys OTS in coordination with DLR as a control tool to utilize existing assets. A two-stage stochastic unit commitment framework is used to deploy the proposed FTDLR model, which is used to dynamically increase the line capacity based on the meteorological parameters and at the same time optimally select candidate lines to be switched off from the network. A comprehensive analysis is performed to characterize the FTDLR performance on system operation cost, network congestion, and wind power curtailment. The proposed FTDLR model is further tested as a part of contingency analysis where both generator failure and transmission line outages are considered. Test results performed on the IEEE 24-bus network demonstrate that by using FTDLR, the service operator could substantially reduce system dispatch cost, improve wind power accommodation, and relieve network congestion. The scalability and feasibility of the FTDLR optimization problem is validated on the larger network of the IEEE 118-bus system.

All power converters, including dual-active-bridge (DAB) dc–dc converter, cannot sustain a consistently high-efficiency performance over a wide range of operating conditions, and reconfiguration of operation mode represents a viable solution to this fundamental problem. To meet this challenge, a resonant-type three-phase DAB (3p-DAB) converter incorporating a three-phase reconfigurable resonant network has been proposed in this article. The proposed converter can operate either as a 3p-DAB resonant immittance converter (3p-DABRIC) or a 3p-DAB series resonant converter (3p-DABSRC) to enhance its efficiency performance over a wide range of voltage conversion ratio and output power levels. In addition, the proposed converter offers the flexibility to operate with unity power factor, full-range zero-voltage switching, and enhanced light-load efficiency under varying operating conditions by appropriate selection of the converter's operation mode. Based on a careful loss analysis and verification of the loss model by experimental measurements, it has been found that under wide range variations in voltage conversion ratio and output power levels, 3p-DABSRC delivers a more superior efficiency performance at low to medium power levels, whereas 3p-DABRIC generally achieves a higher efficiency at high power levels, and thus combination of both operation modes leads to an overall wide range high-efficiency performance.

This paper proposes a three-phase dual-active-bridge (3p-DAB) dc–dc converter that utilizes three-phase resonant immittance network (3p-RIN) to achieve the unity power factor operation. The proposed 3p-RIN maintains the unity power factor operation at both ac links of the 3p-DAB over full range of operation; thus, mitigating the reactive power loss. It can perform the full ZVS operation as well for diminishing the switching losses. For the unity power factor operation, the converter operates in in-phase mode between primary and secondary side voltages, whereas for the full ZVS operation, the converter operates in lagging phase relationship between the primary and secondary side voltages, respectively. The power flow through the converter is controlled by modulating either internal (for unity power factor operation) or both internal and external phase-shift angles (for full ZVS operation); thus, providing two degrees of freedom. A detailed evaluation of the converter is performed using the fundamental component analysis for voltages and currents of 3p-RIN. The theoretical analysis is supported by the experimental results obtained from a 400-V/220-V, 2-kW prototype operated at both unity power factor and full ZVS operating modes. The unity power factor operation gives better performance as compared to the full ZVS operation for the selected specifications of the converter.

The problem regarding environment has been considered as contemporary issue, and to cater this, various technologies have been revolutionized in vehicle transport field. Efforts have been made to make vehicle engine efficient and introducing hybridized vehicles with the aim of reducing emissions and less fuel dependency. In essence of this, trends of solar electric cars in different countries have been reviewed. Feasibility analysis is done by doing fuel cost analysis of two cases, i.e., simple hybrid vehicle and hybrid vehicle equipped with solar module and increased battery energy storage capacity for a specific round trip distance between two cities, i.e., Rawalpindi and Islamabad in comparison with feasibility of third case, i.e., proposed solar electric car model. The solar module selection along with desired number of batteries with charging and discharging time and motor power required to carry five persons weight (70 kg each) is calculated for third case. Moreover, total carbon dioxide emission analysis has been carried out from car material production to its assembly, manufacturing solar module and nickel metal hydride battery for each case. The annual carbon dioxide emitted from fuel in first two cases relative to electric outlet in third case for specific distance has been analyzed. On large scale, emission analyses for hundred cars of each case have been done at 100 km distance. From calculations, it is revealed that overall emissions in third case on large scale and from its material production, assembly, solar module and batteries manufacturing perspective are comparatively less than other cases.

Energy harvesting from solar photovoltaic (PV) modules is affected by partial shading (contributes to mismatch issues), which in turn affects the entire system efficiency. Various power electronics converters have thus been investigated to address the mismatch issue due to partial shading, where the charges between PV submodules (typically, three submodules in a PV module) are redistributed. As a representative of the power electronic-based techniques, differential power processing (DPP) converters can improve the power extraction from the series-connected PV submodules. In this paper, a switched-capacitor-inductor (SCL)-based DPP converter is proposed to mitigate the mismatch effect for PV modules. The proposed converter only processes the differential power, enabling extraction of the maximum power from the PV module at a submodule level. The proposed topology is analyzed and compared with the traditional (Schottky) bypassing technique through simulations. Partial shading experiments are also performed for the traditional technique. A benchmarking with the prior-art DPP converters and experimental tests on the switched-inductor (SL)-based DPP topology are presented in this paper.

All power converters, including dual-active-bridge (DAB) DC-DC converter, cannot sustain a consistently high-efficiency performance over a wide range of operating conditions, and reconfiguration of operation mode represents a viable solution to this fundamental problem. To meet this challenge, a resonant-type three-phase DAB (3p-DAB) converter incorporating a three-phase reconfigurable resonant network (3p-RRN) has been proposed in this paper. The proposed converter can operate either as a 3p-DAB resonant immittance converter (3p-DABRIC) or a 3p-DAB series resonant converter (3p-DABSRC) to enhance its efficiency performance over a wide range of voltage conversion ratio and output power levels. In addition, the proposed converter offers the flexibility to operate with unity power factor, full-range zero-voltage switching (ZVS) and enhanced light-load efficiency under varying operating conditions by appropriate selection of the converter’s operation mode. Based on a careful loss analysis and verification of the loss model by experimental measurements, it has been found that under wide range variations in voltage conversion ratio and output power levels, 3p-DABSRC delivers a more superior efficiency performance at low to medium power levels, whereas 3p-DABRIC generally achieves a higher efficiency at high power levels, and thus combination of both operation modes leads to an overall wide range high-efficiency performance.

A three-phase dual-active-bridge (3p-DAB) DC-DC converter employing three-phase resonant immittance network (3p-RIN) has been proposed in this paper to attain unity power factor operation at both ac-links of the 3p-DAB converter for mitigating the reactive power loss. Besides unity power factor operation, the proposed converter can perform full ZVS operation as well for all the switches to minimize the switching power loss. The unity power factor operation is performed by keeping the primary and secondary bridge voltages in phase whereas the full ZVS operation is performed by keeping the primary and secondary bridge voltages in lagging phase relationship. For unity power factor operation, the power flow through the converter is regulated by modulating the internal phase shift angle, whereas for full ZVS operation, the power flow is modulated utilizing both internal and external phase-shift angles. Fundamental component analysis for voltages and currents of 3p-RIN is used to carry out the detailed modeling of the converter followed by the validation from a 400 V/220 V, 2 kW hardware prototype for benchmarking the cogency of the proposed topology. The hardware prototype has been operated in both unity power factor and full ZVS modes of operation. More superior performance was discerned for the unity power factor operation as compared to the full ZVS mode of operation for the selected specifications of the prototype.

Generator Excitation System is used to provide the DC supply to the field winding for producing the magnetic field in the generator. It is considered as a main part and backbone of the generator. Excitation system also provides stability of the power system by controlling the system voltages which can be enhanced for considering some key factors. In this paper performance evaluation of new static excitation system of Tarbela power station has been carried out. In Tarbela there are two types of Excitation for different generating units i.e. rotary and Static Excitation system. In this paper different test results of new state of the art static excitation system has been presented and compared with the rotary excitation system. Some new features of static excitation system are also discussed for improving the response and stability of the power system.

Integration on large scale of distributed generation into the distribution system can change the role of system from passive to active but also show significant changes in planning approach, distribution network operations and designing. Planning approach that is being used for today's distribution system can't fulfill the integration method for distributed generation and conventional system in an economical way because of the fact that planners are not able to deal with complex environmental decisions and lower development budgets for renewable. This review paper proposes the key facts that should be under consideration to make the distribution network more economical for the integration of renewable.

Exponential escalation in the energy requirements and depletion of mineral resources has forced scientists to recycle and find the most optimized way of using the mineral resources left on earth. Transformers are the most mineral consuming devices of the power distribution systems as the use of core and winding has a high mineral content. In this paper a solution has been proposed to solve this problem and provide with an optimization technique for the minimum volume used to develop transformers. The technique models the materials, using the dependence of material on the magnetization parameters and uses genetic algorithm to perform optimization.

Generation expansion planning (GEP) problem involves determining new power plants in terms of type, capacity and allocation for meeting future load demands. The GEP problem incorporates large number of constraints and it is a highly complex, large scale, non linear optimization problem. Large scale integration of Renewable Energy systems (RES) in GEP problem has always been averted by the high cost and poor availability rates of RES as compared to conventional fossil fuel fired power plants. However internalizing environmental externalities in GEP problem could help to promote large scale integration of RES. The proposed model in this paper examines the effect of internalizing externalities on the GEP problem. External cost values for China are evaluated using the unit damage costs of pollutants. The model has been implemented in MATLAB using Genetic Algorithm and is applied to a case study of one of the district power companies of China. The results show significant structural changes in favor of RES confirming that internalizing externalities can be used as a driving policy tool for large scale integration of RES.

With the development of Smart Grids worldwide, efforts have been focused on optimizing the role of Smart Grid in the present electrical system. The integration of renewable energy resources to the grid presents a great challenge since they are intermittent and vary constantly causing frequency fluctuations. Automatic Generation Control (AGC) solves this problem by keeping the frequency close to nominal value and maintaining the balance between generation and demand. AGC has been implemented in various softwares as an added functionality. Power Systems Analysis Toolbox (PSAT) is a MATLAB toolbox designed for power flow computations but it lacks AGC implementation. This paper presents AGC implementation on PSAT using Artificial Neural Networks (ANN) controller and PID controller. The goal is to optimize PSAT by adding extra functionalities to it. The AGC design is implemented on IEEE 14-bus system on PSAT. A comparison of ANN controller and PID controller is also presented. The results show successful addition of AGC to PSAT library. The AGC design helps to control the frequency, has high performance and can be extended to other power systems.

An accurate digital distance relaying scheme integrated with artificial neural network impedance estimator is developed using the weighted sum of the negative-zero sequence components of fault current assuming the voltage and current are in phase at the fault location. The modified scheme is immune to the variation in fault location for under reach and overreach problem caused by sequence current components. A series of test conducted on a 800kV, 400km transmission line for single phase to ground faults as well as simultaneous open conductor fault in PSCAD/EMTP and Matlab. Finally comparison has been done with the conventional methods in order to check the accuracy and robustness of the proposed scheme which is found to be 95%.

Risk of global climate change and confronting of tumbling carbon emissions necessitate new ways to collaboratively control and optimize energy production and load. Uncertainty in generation and demand for electric energy require elastic generation capacity and stochastic optimization of generation schedules. The introduction of time-variable energy tariffs is a loom to attract consumers to shift their energy loads into low demand periods. In this paper we will build a model to solve an economic dispatch problem with integration of stochastic demand side response so that the demand can be shifted from peak load hour to off-peak load hour. Unlike other models we will introduce the customer's willingness to shed their load by giving the price signal an hour ahead of time. In this paper we will also emphasis that neither the price signal should be given too high that the customer cut most of the load by transferring all to the off-peak hour nor it should be too low that the generation utility becomes unable to raise enough profit. The simulation shows the promising results of shedding the load on profitable price signals.

Protective relaying system plays a vital role in ensuring the proper and smooth functioning of the Power plant. As the generator is the most expensive part of the plant that’s why the provision of a healthy protection system is must. Protection system guarantees the reliability and safe operation of the plant and is called the brain of the power system. Tarbela is the largest power plant of Pakistan and considered as a back bone of power system of Pakistan. In this paper, the generator protective relay of Tarbela power plant is tested and their results are presented. All the protective relays of Tarbela Power Plant are of electromechanical types which were manufactured in 1970-80. Setting, calculation and test result of these relays were then analyzed and recommendation is made for improving the reliability of the protection system of the said plant. Features of new numerical relays and comparison with the installed relays are also presented and finally the description of upgradation/retrofitting of installed electromechanical relay are discussed for smooth transition to new technology.