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Vacuum as switching medium has been established widely in the distribution systems for more than 30 years. Well known for its outstanding and reliable interrupting capability of fault and load currents of all possible nature, the vacuum switching technology is now dominating the medium voltage level up to 52 kV. Technical advancements in the field of vacuum physics in last decades made it possible...
Transmission line switching is an important operational action in power transmission systems, and has been successfully applied to reduce generation costs and eliminate congestions. Prior work mainly focus on tackling the Optimal Transmission Switching problem based on steady states. This paper studies how to generalize these results when transmission switching is performed on highly congested systems...
An adaptive power supply regulator based on pulse skip modulation (PSM) with fast transient response is proposed in this paper. The controller of the adaptive regulator includes a clock generator, a delayline, two flip-flops, two comparators, a pulse width generator and a NAND gate. For output voltage segmentation is used, the maximum conduction duty ratio of the power switch is not limited by the...
The U.S. Coast Guard's 270-ft Medium Endurance Cutter (WMEC) is a powerhouse of the Coast Guard fleet filling a critical role in defense of the homeland. While the U.S. Navy has conducted extensive research into the use of zonal DC electrical distribution systems (DCDS) for their ships, no project has analyzed the installation of DCDS on a Coast Guard cutter which has a significantly different load...
There are difficulties in detecting low voltage ride through (LVRT) ability of offshore doubly fed induction generator (DFIG) because of complexity of sea condition. In this paper, a new scheme is put forward to solve this problem. This new scheme takes into account the effect of submarine cables on transient process of circuit, and the influence on short-circuit capacity of remote point. It proposes...
This paper proposes a new configuration of distribution system, Flex-Grid that dynamically and adaptively re-configures in real-time to maximally utilize the renewables, improve energy efficiency, reliability and power quality, particularly if the system includes distributed generations and energy storages. A multi-objective optimal scheduling method is provided to partition the system into self-sufficient...
This paper proposes a method to determine the temporal-dependencies concerning the parameters of time variable systems. The method utilizes sensitivity functions. The case of the switching-regime systems which have parameters whose values change from an operating regime to another will be investigated. Using the proposed method the transient response of the system model can be improved without changing...
Transmission line congestion is a critical factor that will affect power system operational cost. With more renewable energy in the future grid and the intermittence of nature, transmission line congestion will be more frequent. Due to the congestion, renewable plant has to curtail some available generation. This paper investigates the use of active transmission line switching operation in power system...
In this paper, the voltage regulation and transient stability of the multi-machine power systems are studied via decentralized switching controller. In most existing works, voltage and frequency stability of the multi-machine power systems are controlled by different controllers in different periods of power systems operation. The linearized model of the power system is established, and it takes both...
This paper proposes a new concept of adaptive ramp generation to enhanced the transient response of PWM voltage mode buck converter. Based on a simple ramp slope controller, the proposed adaptive ramp generator can output ramp with different slopes to accelerate duty ratio adjustment so as to reduce the voltage variations (voltage spikes) and the transient recovery time. A PWM voltage mode buck converter...
Effective simulation of large-scale power system disturbances especially those stemming from intentional attack represents an open engineering and research problem. Challenges stem from the need to develop intelligent models of cyber-physical attacks that produce salient disruptions, to appropriately portray meaningful cyber-physical interdependencies, and balance precision, scale and complexity....
This work is concentrated on transfer of power quality disturbances in active distribution network containing small hydro power plants (SHP). Investigations are based on the dispersed synchronized measurements using power quality recorder installed in the two substations connected to the same medium voltage line. Dynamic aspect of SHP work represented by switching on capacitor banks are tracked in...
The aim of this paper is to present a three-phase 6×4 switched reluctance generator load voltage control. The showed strategy uses a PI controller to vary the magnetization level of the phases during the magnetization period using a PWM signal. This strategy was simulated and than tested in a bench. Results of both simulations and experimental tests are presented here. It was used a low cost fixed-point...
In the computer centre, a safe electrical supply is crucial. Very common is the UPS, which is however suitable for short blackouts only. During a long black out it is necessary to use a larger UPS or rotary generators. In this article the authors describe their experience obtained by measurement in various situations: A large UPS, or a small UPS used simultaneously with unsuitable generator. The attention...
This paper presents the dynamic characteristics of the proposed digital control current mode dc-dc converter. In the proposed novel digital control circuit, the peak current-injected control is realized using the combination of the simple dual A-D signal converter and the programmed delay circuit. In 100 kHz digitally controlled dc-dc converter, it is seen in simulation that the proposed method has...
With ambitious 2020 targets for increased energy efficiency and utilisation of sustainable energy sources fast approaching, the UK's electricity networks will need to adapt in order to integrate the vast amounts of small, distributed energy sources required. Microgeneration sources rated below 16A per phase will likely make a significant contribution to meet these targets, and as such a great deal...
This paper discusses the feasibility of three-phase switching of six-phase lines for single phase-to-ground faults as a protection scheme. To apply such scheme, it is necessary that the transient stability, extinction of secondary arc current, thermal duty of nearby generators and torsional torques induced on the shaft of turbine-generators are investigated and compared with single-pole switching...
This paper mainly deals with the transient stability analysis of a 3Phi double circuit line in comparison with that of equivalent 6Phi transmission line. The method of conversion of 3Phi double circuit line into 6Phi line using 3Phi/6Phi transformers and the method of obtaining corresponding equivalent p.u. reactance values are explained. A computer program in MATLAB is developed using Gauss-seidelpsilas...
Due to their reconfigurability and their high density of resources, SRAM-based FPGAs are more and more used in embedded systems. For some applications (Pay-TV,Banking, Telecommunication ...), a high level of security is needed. FPGAs are intrinsically sensitive to ionizing effects, such as light stimulation, and attackers can try to exploit faults injected in the downloaded configuration. Previous...
Today, to take advantage of better availability, lower maintenance and easier control, drivers of large equipments in Oil & Gas plants are more and more electrical motors driven by variable speed drive systems. So the needs for electrical power are going up. In addition the plants are located in places where the network is insufficient or not safe enough to guarantee the required reliability /...
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