Chakrabarti B.B.,Transpower |
Rayudu R.,Victoria University of Wellington
2013 IEEE Innovative Smart Grid Technologies - Asia, ISGT Asia 2013 | Year: 2013
Wind generators (WTGs) can be classified as two types: Fixed speed wind generator (FSWTG) and Variable speed type (VSWTG). The variable speed type has a number of variants such as Doubly Fed Induction Generator (DFIG), Multi-pole Synchronous Generator, and Permanent Magnet Synchronous Generators. DFIGs are already complying with most of the operating requirements set by different markets. The next stage is the inertial energy support during frequency events, particularly during large events. This paper discusses the emulation of inertial response of DFIGs in 3-steps - how the Kinetic energy stored in the rotating blades of variable speed wind generators is extracted by using a supplementary control system. The 3-steps used are 1) only electrical system including WF inertial support, 2) hydro dominated electrical system with WF inertial supports, and 3) multi-bus network with different generators and WF having full model of DFIGs. © 2013 IEEE.
Hettiwatte S.N.,Murdoch University |
Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012 | Year: 2012
Condition monitoring plays a vital role in any asset management plan. Dissolved gas analysis is a routine test carried out on power transformers to monitor their condition. Four power transformers selected from a repository of power transformers due to their dissolved gas levels exceeding the normal levels are analyzed using the Key Gas Method, the Roger's Ratio Method and the Duval Triangle Method to diagnose any faults. The results show that for some transformers all three diagnosis methods agree on the type of fault, whilst for others it is not so straightforward in diagnoses. In this study, the condition of each power transformer is predicted using the above methods. © 2012 IEEE.
Marshall R.A.,IPS Radio and Space Services |
Dalzell M.,Transpower |
Waters C.L.,University of Newcastle |
Goldthorpe P.,University of Newcastle |
And 2 more authors.
Space Weather | Year: 2012
Adverse space weather conditions have been shown to be directly responsible for faults within power networks at high latitudes. A number of studies have also shown space weather to impact power networks at lower latitudes, although most of these studies show increases in GIC activity within networks not directly related to hardware faults. This study examines a GIC event that occurred in New Zealand's South Island power network on 6th November 2001. A transformer failure that occurred during this day is shown to be associated with a change in the solar wind dynamic pressure of nearly 20 nPa. Measurements of GICs recorded on the neutral lines of transformers across the Transpower network during this event show good correlation with a GIC-index, a proxy for the geoelectric field that drives GIC. Comparison of this event with GIC activity observed in the Transpower network during large space weather storms such as the "2003 Halloween storm," suggests that solar wind shocks and associated geomagnetic sudden impulse (SI) events may be as hazardous to middle latitude power networks as GIC activity occurring during the main phase of large storms. Further, this study suggests that the latitudinal dependence of the impacts of SI events on power systems differs from that observed during large main phase storms. This study also highlights the importance of operating procedures for large space weather events, even at middle latitude locations. © 2012 by the American Geophysical Union.
Kwasinski A.,University of Texas at Austin |
Eidinger J.,G and e Engineering Systems |
Tang A.,L and T Consultant |
Earthquake Spectra | Year: 2014
From late-2010 to mid-2011, Christchurch suffered a series of earthquakes and aftershocks that affected the city's power supply. The most relevant of these events occurred on 4 September 2010, 22 February 2011, and 13 June 2011. In all these events transmission level power restoration occurred rapidly- within one day. Except for the second event, similar relatively minor damage led to rapid restoration of distribution-level power outages. However, extensive damage to underground cables during the February 2011 earthquake caused some outages that lasted until early March. This damage seems to be amongst the only extensively-documented such failures to date. Despite recorded strong ground shakings, damage to other power infrastructure facilities was moderate to minor. This satisfactory performance of power infrastructure is attributed to a program implemented during the decade prior to this earthquake sequence to seismically upgrade almost all unreinforced masonry substation buildings and reinforce other infrastructure elements. © 2014, Earthquake Engineering Research Institute.
44th International Conference on Large High Voltage Electric Systems 2012 | Year: 2012
An important part of identifying the reliability or remaining life of transmission line towers/foundations is to know their actual capacity. Another aspect that is not yet well defined is tower/foundation interaction under dynamic wind gusts or ultimate design loads. A required realignment of a double circuit 110kV line gave us a unique opportunity to do some full scale testing on two consecutive suspension towers that had been made redundant. The two towers were from the same family of towers and line that was being considered for tower/foundation strengthening due to capacity concerns from recent re-conductoring and minor uprating. At one site (T27) the tower was dismantled leaving the steel grillage foundations intact and available for individual "static" uplift testing. The foundations were in similar soil conditions to the other tower, and representative of the rest of the line. The standalone foundation tests were undertaken using a dedicated foundation test beam. The foundations were tested consistently to the IEC standard for a "static" test complete with applied load and deflection measurements of the stub and sub-surface layers. At the other site (T26), the tower was located on a ridge with plenty of room for setting up the test arrangement and adjacent to its replacement tower which due to supply issues was of 220kV design and much larger. The tower was instrumented with strain gauges and load cells, and loaded through a cable arrangement back to a pair of dozers. Transverse and vertical loads were applied to the tower through a single sloping cable at each crossarm level. The heart of the test was the ability to apply a slow effectively "static" load for comparison with a static tower analysis and standalone foundation testing, but also to simulate a relatively fast and short duration dynamic load with failure at 120% of the expected static failure load.