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Stockbridge-type aeolian vibration dampers, if properly chosen and applied, have proven to be effective to protect overhead lines from harmful wind-induced vibrations. However, conventional dampers with bolted clamps may have shortcomings in damping high frequency vibrations of small diameter optical ground wires (OPGW) due to their high clamp mass. Theoretical considerations based on wave impedance...
The potential differences caused by the current injected in the ground by a HVDC-electrode can cause corrosion of e.g. pipelines and operational problems in transformer stations. Also, hazardous electric fields can arise in the vicinity of HVDC- electrodes. High potentials and strong fields from electrodes are, in principle, related to high-resistivity rock in the ground. The presence of such potentially...
Hot spot temperature is the main limiting factor of transformer loading. On the other hand, supposing the frequency being constant, voltage increase will result in transformer over-excitation. When the transformer is over-excited, the no load loss and subsequently the hot spot temperature will increase. Thus, the transformer loading will be restricted. In this paper, the problem of loading capability...
A spectral analysis of the electrical power draw of the two 5.2 MW motors driving a large grinding mill is performed to determine whether they are the source of a severe 55.8 Hz vibration. The applicable electrical and mechanical data was measured during October 2006 and recorded with a sample rate of 5 kHz over a few minutes. It is shown that the motors do not supply the mechanical system with any...
China is currently pushing on constructing plusmn800 kV UHVDC power transmission projects. The Yunnan-Guangdong power transmission project to be built in 2009 will be the first UHVDC power transmission project around the world. The paper has presented insulation level and insulation coordination for the key equipment, which would be adopted in the Yunnan-Guangdong UHVDC Project. The research result...
In the AC & DC hybrid system (ADHS) in China Southern Power Grid (CSG), many long-distance, huge-capacity transmission lines operate in parallel. So the reaction and performance of AC & DC system during faults and disturbances have great effect on the stabilization of ADHS. This paper sets up the detail PSCAD/EMTDC models of CSG and analyzes its dynamic performance under different kinds of...
Due to its simple structure and lower price, the resistive type superconducting fault current limiter (RSFCL) is being used widely in practical experiences. As RSFCL needs considerable time to return from the normal zone to the superconducting zone after the fault clearance, operating in normal zone may create some problems. Since the number of faults on distribution systems is much more than the...
Due to its simple structure and lower price, the resistive type superconducting fault current limiter (RSFCL) is being used widely in practical experiences. Since these equipments are installed to provide high levels of power quality for sensitive consumers, it is necessary to investigate their harmonics generation. In this paper harmonics generation of a RSFCL is considered and a method is presented...
This paper make a brief introduction to overload capability of HVDC, and show the necessity and feasibility of using overload capability of HVDC in China Southern Power Grid. Overload capability of Tian-Guang HVDC and Gui-Guang HVDC transmission systems and its practical use in China Southern Power Grid are analyzed. Some problems in the practical use are pointed out and solutions to these problems...
This paper describes a case study to find the location of the voltage sag source at a petroleum industry where sags are causing undesired trips on critical loads. The network that supplies this industry is operated by basically two transmission and distribution utilities. Therefore, finding the location of the disturbance source is a first step in mitigation and decisive in allocating responsibilities.
In order to meet South Africa's future electricity demand, Eskom has initiated a process to evaluate the feasibility of various power generation options. Coal fired generating options are envisaged to remain a fundamental part of South Africa's power generation options. ISEP (integrated strategic electricity planning) indicated that new base load power generation will be required no later than 2011...
This paper presents the basic structure parameters of 800kV DC composite insulator specimen and the pollution test scheme. The condition of 800kV DC composite insulator pollution test under whole 800kV voltage and whole structure dimension completed in STRI, which is completed first time in the world, is introduced. The study results indicate that the linear relation between the pollution flashover...
A review of the condition assessment methods of porcelain insulators shows that there is motivation for further improvements particularly regarding applications in distribution systems. Acoustic and high frequency (HF) methods are quite attractive mainly due to better immunity to noise and the relative easiness with which they can be adapted to in-service monitoring applications. These methods have...
Electrical faults due to leaning trees have been studied in [1]-[2] and it was found that the initial transients due to the associated arc reignitions are behavioral traits. These transients have been localized using the discrete wavelet transform (DWT). In this paper, these features are extracted from residual voltages using DWT. Therefore, the fault localization is carried out. The term for locating...
Power system controller design based on an evolutionary algorithm called population based incremental learning (PBIL) is proposed in this paper. The problem of controller design is transformed into an optimization problem and the parameters of the controller are determined via PBIL. The proposed method has the advantage that it is simpler, faster and more efficient than both the classical trial and...
The capacitor-commutated converter (CCC) has frequently been used in the conception of HVDC systems connected to busbars with low short circuit level. This alternative arrangement, in substitution to the conventional ones, guarantees less sensitive operational conditions to problems related with the commutation failure in the inverters besides supplying part of the reactive energy to be compensated...
Site specific wind speed measurements are critical for techno-economical development of wind energy applications. This paper presents the wind power potential at Rawdat Ben Habbas village where meteorological measurements were made using a 40 meter tall wind tower for a period of one year. The wind speeds were recorded at 20, 30 and 40 meters above ground level (AGL) and the wind direction at 30 and...
Utilities must ensure that they have adequate generator reserves to allow for possible plant outages and electricity demand forecast errors. If an excess of plant is committed, then this will result in unnecessary fuel usage. This will result in an increased cost of producing electricity. On the other hand, if too little plant is committed then expensive quick start plants such as gas turbines may...
This paper presents a substation grounding grid analysis with the variation of soil layer depth. The grounding grid system of a practical 22 kV substation, in which the ground grid is made from copper, is calculated by virtue of the CDEGS software. The study, supported by Provincial Electricity Authority (PEA), Thailand, is based on grounding grid system of Royal Flora RATCHAPHRUEK substation. The...
Utilities require a high storage capacity to characterize voltage sag on the power system network. The RMS has limited capability and can only acquire event magnitude and duration information. In this paper the authors propose a measurement technique based on instantaneous tracking of the amplitude phase and frequency of a non-stationery sinusoid. From the tracked parameters, the amplitude, duration...
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