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The Railbelt grid: an operational puzzle Utilities continue to consider unifying the entire grid under single operator and single ownership structure to simplify management Alan Bailey Petroleum News
For a number of years and through multiple investigations the question of whether and how to unify the Alaska Railbelt power transmission grid under a single management structure has been a regular topic of conversation. In 2010 the concept reached the state Legislature in the form of a bill to establish a corporation to develop, maintain and operate the entire grid. And, after that bill failed to pass, some of the utilities that operate the grid formed a cooperative called the Alaska Railbelt Cooperative Transmission and Electric Co., or ARCTEC, to at least coordinate grid upgrades.
The grid stretches from Fairbanks in the Alaska Interior, south through the Matanuska and Susitna valleys and Anchorage, to Homer and Seward in the southern Kenai Peninsula. Despite its small size in terms of power throughput, the grid is owned by six distinct electric utilities, with the State of Alaska also owning one segment of the line.
The topic of grid unification emerged again during a Nov. 6 meeting of the Anchorage Mayor’s Energy Task Force when Brian Hickey, executive manager, grid development, for Chugach Electric Association, told the task force that the Railbelt electric utilities continue to discuss possible ways in which grid unification might be achieved, given the significant benefits that unification would bring.
One machine “From a system perspective the transmission grid is one machine,” Hickey said, explaining that generators feeding power into the grid at different points along its length all have to spin at the same speed, synchronizing their output of alternating current at a fixed 60 cycles per second frequency. If the load on the system exceeds the generation capacity, the power generation will slow down and ultimately come to a halt, rather like an underpowered car trying to negotiate an uphill stretch of road. Conversely, an excess of generator output overload will cause a speeding up of generation and trigger system instability.
A power load increase in Fairbanks at one end of the grid should have an almost instantaneous impact on a power generator in Homer, at the other end, as the generator adjusts to the load change. And so, operators of the grid must load balance on a second-by-second basis, to ensure the maintenance of power supplies and the continuity of the 60 cycles per second frequency, Hickey said.
Multiple utilities At present three utilities that own generation capacity, Chugach Electric Association, Municipal Light & Power and Golden Valley Electric Association, conduct the load balancing, using a set of agreed rules for how the balancing is done and with each utility being responsible for its own sector of the grid, Hickey said. But the grid is entering a period of major upheaval, as wholesale power sales agreements between Chugach Electric and two other utilities, Matanuska Electric Association and Homer Electric Association, come to an end, causing these utilities to construct and operate their own power stations.
When the new power generation goes into operation, Homer Electric and Matanuska Electric will become responsible for load balancing in their regions, thus expanding the number of utilities conducting load balancing from three to five, an expansion that will complicate the load balancing arrangements, Hickey said. The complications are compounded by difficulties in achieving agreements between the utilities over load balancing rules and associated cost allocations, with at least one of the utilities joining the load balancing system disagreeing with the existing rules, he said.
In the Lower 48 load balancing complications within a region are generally resolved by establishing an independent system operator, or ISO, with authority to control the dispatch of power and ensure non-discriminatory access to the transmission system across the entire region, Hickey said. And a regulated transmission company known as a transco typically owns the assets of the grid, manages grid upgrades and secures financing for the upgrades, he said.
The transco pools all costs associated with the grid and recovers these costs through rates charged to the grid users. The ISO has authority over the transco, ensuring that an adequate transmission system is built, assuring the recovery of rates and, as necessary, ensuring short-term reliability of power supplies.
Alaska possibilities The Railbelt utilities have been discussing a similar arrangement for Alaska and have coined the name Railbelt Reliability Authority, or RRA, for an ISO that could potentially oversee the grid, implementing a single, system-wide rate for power transmission, rather than having the current complex rate structure, Hickey said. ARCTEC could potentially become the transco for the grid, taking responsibility for grid upgrades and maintenance and pooling the costs across all users. ARCTEC would likely contract work back to the entities that originally maintained the transmission assets, but with the assets either being transferred or pledged to ARCTEC.
This type of arrangement would make the funding of transmission upgrades more feasible than otherwise: Benefits from the upgrades would mainly come in the form of cost savings that ARCTEC could offset against the upgrade costs in the rates that it charges for grid usage, Hickey explained.
However, the main obstacle to establishing a grid management system of this type has been misalignment between the costs and benefits across the different existing utilities, he explained. If a grid unification initiative results in a benefit for the grid as a whole, but that benefit disproportionately applies to perhaps one or two utilities, the other utilities that lose out will not agree to the funding of the initiative, he said.
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