Austria is the latest country to adopt an ABB wide-area monitoring system (WAMS) together with ABB phase-shifting transformers to monitor and increase the stability of its power transmission network. WAMS is an advanced early warning technology that helps grid operators avoid system instabilities, overloads and power black-outs.
WAMS (Wide-area monitoring system) technology solves one of the power industry’s most pressing problems – that of detecting and counteracting the first signs of grid instability. The Austrian utility, Verbund-Austrian Power Grid (APG), has installed a new ABB monitoring system to complement three recently commissioned phase-shifting transformers (PSTs) in critical substations to optimise transmission over main power corridors.
Since Spring 2006, ABB’s PSGuard 850WAMS has overseen the power flow along a crucial and heavily loaded transmission corridor between north-eastern and southern Austria, connecting the cities of Vienna and Ternitz. The APG operated corridor controls a power network consisting of about 50 switching/substations, and 6,500 kilometres of lines.
HEAVY LOAD
Much of Austria’s 1,900MWof surplus power is produced in the north east of Austria but needs to be transferred to the south of the country where there is a 1,400MWdeficit. To meet the south’s heavy demand for power, surplus electricity is transmitted over three 220kV power lines which have a total capacity of 1,200MW. However, increased congestion can restrict the flow of electricity and threaten the security of supply.
This congestion will be made worse by the gradual addition of another 1,000MW of wind generated power from the north-east, as well as the closure of coal-fired power plants in the south.
ABB’s PSGuard monitoring system with phasor measurement units (PMUs) and three PSTs installed at critical nodes in the network are bringing stability to the transmission corridor
SYSTEM MONITOR
The ABB transformers located in three of APG's substations regulate the power, prevent overloading and protect the power lines. A PST is used for active flow control of 400kV transmission grids.With a throughput rating of 1,400MVA, PSTs are among the biggest transformers ever made, weighing around 800 tonnes. They provide stability by controlling the quantity and direction of electricity. These technologies are enabling APG to get the most out of its existing transmission capacities while significantly reducing the risk of a black-out caused by overloaded lines.
SATELLITE-SYNCHRONIZED MEASUREMENTS
APG’s PSGuard employs applications like phase angle monitoring (PAM), which scrutinizes network stresses caused by heavily loaded lines, and line thermal monitoring (LTM), which determines average line temperature and temperature changes.
Measurements are taken with ABB PMUs – measuring devices installed at critical nodes in the power network which use a GPS satellite signal to time-synchronize voltage and current readings as they are taken from their points of origin.
Data can be streamed into a control centre from across the grid. Operators can see exactly what is happening on their system as well as beyond their own control area – a major advance over traditional monitoring and protection methods.
This means they can react swiftly and effectively when there are sudden interruptions or bottlenecks in the power flow. This gives them time to prevent the disturbances that could bring down the entire network.
“The information, especially on the load flow and average temperature progression on the double lines, will help us to maintain integrity and use our transmission capacity fully,” says Herbert Erven, head of secondary systems at APG.