New Generation Switchgear – point of view
The power brokers
On the simplicity and reliability of new-generation switchgear
Key Words: GIS – Automation – IED – Switchgear – SubStation
They make modern power transmission and distribution (T&D) grids smarter, especially with the increasing use of SCADA, or the process of supervisory control and data acquisition. Pieces of intelligent switchgear are, indeed, in great demand, as utility providers also look to have monitoring systems built into the existing power network to simplify maintenance and troubleshooting. And such move requires for a sophisticated management of networks that will, in turn, place additional demand on switchgear equipment.
Consequently, switchgear manufacturers are now including built-in protection and control intelligent electronic devices (IEDs) in their switchgear solutions. This enables communication between the protection and control IEDs of distribution switchgear with the substation control room. Until just a short time ago, this could only be achieved by adding various different specific components to the normal protection relays. Now, every company is working to push these boundaries.
ROOM FOR IMPROVEMENT
However, switchgear technology has not reached its operational limits, and there is still room for technological breakthroughs. For example, companies are continuously investing in research and development to minimise the circuit breaker energy, to break higher and higher currents.
As new technologies and concepts start shaping the T&D sector, the original equipment manufacturers (OEMs) of switchgear are adapting to these changes. The introduction of power electronics has revolutionised the concept of switchgear and has enabled new applications.
Referring to the combination of electrical disconnects, fuses and circuit breakers used to isolate electrical equipment, a piece of switchgear is used in association with the grid (electric power system). It may be a simple, open-air isolator switch or it may be insulated by some other substance, such as GIS, or gas-insulated switchgear.
In GIS, the conductors and contacts are insulated by pressurised sulfur hexafluoride gas (SF6) while the other common types of switching devices are oil- or vacuum-insulated switchgear.
The new-generation switchgear pieces are simple and reliable, and they leverage the magnetic actuator mechanism to be as trouble-free as the latest interrupter technology. Currently being applied to low-voltage switchgear, these actuators will replace old technology air circuit breakers in medium-voltage (MV), high-voltage (HV) and, eventually, extra high-voltage (EHV) switchgear.
Switchgear pieces are used in substations on both sides – the incoming HV and the outgoing distribution of low voltages from large power transformers. The switchgear located on the low voltage side of the transformers in distribution substations now typically comprises the power distribution center (PDC). Inside this are smaller, MV circuit breakers feeding the distribution system; various relays, metres and other communication equipment. This setup allows for intelligent control of the substation.
Today, the emerging trend in power substations is of the hybrid variety, which combines various types of switchgear. A hybrid substation is a combination of conventional airinsulated switchgear (AIS) and the newer metalclad GIS switchgear. A hybrid has transportation advantages, too, as it fits into a standard truck container and does not require any packaging.
ABB’s Pass MO design, rated up to 170kV, is the best example of the versatility of a hybrid substation. It uses existing GIS components with a conventional AIS bus to connect the various hybrid modules. This eliminates the need for separate pieces of equipment for each function, as all necessary substation switchgear bay functions are integrated in one compact module. It can also be installed as a high voltage bay on a mobile truck for use in emergencies, or if work has to be carried out on existing HV bays.
ABB’s GIS ELK-3
A modular approach to hybrid substation design is ideal during the design and construction phases, as this can save up to 70% of the space normally required for a conventional AIS substation. Hybrids may also be intrinsically reliable and maintenance-free, owing to their combined disconnector/ earthing switch, whose mechanism has a minimal number of mechanical components. And with the integrated nature of modern plant facilities, hybrid substations enable electronic monitoring and online remote diagnostics.
The evolution of smartgrids embraces the convergence of legacy utility, regional power control and management systems as embodied in intelligent switchgear. Smart switches, which feature programmable logic controllers (PLC), allow an integration of distributed power grids within that regional control and management system for more agile power deployment. These also allow the integration of regional systems with the national grid for a more responsive power flow control
|GCC powers switchgear demandGlobal demand for T&D equipment rises 4.4% per annumThe GCC Interconnection Grid, which will fully link up the member-states of the Gulf Co-operation Council by 2011, is fuelling demand for switchgear in the Gulf and the wider Middle East region. The Gulf countries’ drive to expand their transmission and distribution (T&D) capacities within their boundaries and across the region is generating substantial business for switchgear manufacturers.With some parts of the GCC sweating in the summer months due to power outages, the prospect of an energy trading market via a smartgrid is emerging as a good source for switchgear business. The Swiss power and automation technology giant ABB remarked, “We’re seeing double-digit increases in spending across the region.” The company has supplied six substations for phase one of the interconnection grid that linked up Saudi Arabia, Qatar, Bahrain, Kuwait and the UAE.The T&D businesses of Areva have also been active in this project, supplying the Middle East’s first high-voltage direct current (HVDC) substation, as well as an integrated grid automation solution to Saudi Arabia.
With the Gulf countries investing heavily in power infrastructure, it is merely due to its size that Saudi Arabia outstrips its neighbours in terms of the scale of its T&D infra buildup. The kingdom has pledged to invest a staggering $80 billion in its electricity sector over the next decade.
As a consequence of longer distances, electricity has to travel though the GCC interconnection grid. And with higher load demand stemming from increased consumption, new grids are being built to accommodate higher voltage levels.
Utilities benefit from increasing the transmission voltage, which becomes more cost-effective as infra investments are reduced according to the amount of power being transmitted. Higher voltages are thus another factor that companies providing switchgear to utilities in the GCC have to take into account.
According to market analysts, the world electric T&D equipment demand will rise 4.4% per annum through 2011. The industrial and commercial sector will see the strongest gains as cogeneration proliferates, and products like high-voltage transformers become more common outside the utility sector.
– Satish Chavan
Además link Overview SubStation Automation IEC 61850: http://www.ieee.org/portal/cms_docs_pes/pes/subpages/meetings-folder/T_D_2005_2006/tuesday/pn10/05TD0235.pdf