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Southern California Edison - Optimizing Assets for the Smart Grid By Michael Burkhalter Jul 7, 2008 - 9:00:00 AM
The cheapest energy is the energy you don’t waste SCE, like all utilities, must have reserve power capacity. Reserves are secured by either buying power from others or maintaining surplus generating capacity. The transmission system must also have reserve transmission capacity in order to allow minor grid fluctuations while maintaining grid stability. The extra capacity requirement has a cost. Utilities must build extra transmission lines and/or more generating capacity in order to handle the customer load.
SCE is applying its system engineering expertise to explore how using Centralized Remedial Action Schemes (C-RAS) -- instead of traditional RAS -- may reduce such wasted excess capacity. (See SCE presentation link below). System Engineers at Southern California Edison (SCE) believe that one way of not wasting electrical energy is to reduce the amount of extra capacity needed in reserve transmission lines.
Utilities might be taking a double hit on cost · Hit #1 – Labor Costs
Traditional RASs are localized, quick-acting protection algorithms individually installed at substations or control centers across the utility’s territory. However, they are “labor-expensive” because they require sending engineers and technicians to visit and re-visit far-flung sites to keep tweaking these algorithms until they work right.
Additionally, the Western Electric Coordinating Council (WECC), the approval authority for each RAS, takes about a year to do so. After each RAS is approved, SCE can implement, test, and go live – but it takes another 6 months and puts a severe strain on a scarce work force. In May, SCE had 16 RASs approved with another 64 pending. Another 64 cannot be tested and implemented under the old paradigm of engineers crisscrossing the territory making adjustments and re-adjustments. Furthermore, such an oppressive workload creates a morale issue.
· Hit #2 – Shedding too much load
Because these RASs are often localized, they do not take into account sharing load across wider T&D assets. According to SCE’s Patricia Arons, another big problem with traditional RASs is the “one-size-fits-all” dilemma. Such RASs are simply not fine-tuned enough to most efficiently mitigate a particular event. Result: Utilities shed more load than they have to.
Reducing labor costs
So, what if you could round up all those algorithms in one development and test environment -- without your high-paid engineers “leaving home”?
SCE, with the help of a SISCO product is working on that. The Unified Analytic Platform (UAP) -- see SISCO home page link below -- would help develop centralized remedial action schemes using UAP as a unique structured environment that integrates all the analysis, testing, and simulation needed to create more effective and reliable algorithms. Benefit: Centralized development and updates avoid the expense of high-paid engineers traveling long distances to work and re-work localized RASs.
No more wasteful load shedding
The use of C-RAS would allow utilities to determine the optimal loads to shed, even if, for example, the loads may not be in the transmission corridor that is experiencing the contingency. Expected benefits include: · More precise mitigation (For example, just in time and just enough load-shedding that considers all the utility’s assets, not just those at certain locations.) · Simplified design and maintenance · Improved automated testing and data gathering (more data to use in improving effectiveness of RASs)
By reducing the surplus capacity required of reserve transmission lines, a utility may be able to save or import enough additional power to defer building an 800MW generating facility.
Next Steps
If WECC approves going live with the C-RAS, SISCO’s UAP will play a key part in C-RAS implementation and other large utilities should be interested, according to Herb Falk, SISCO’s Solution Architect.
The question that WECC is raising is whether the testing with a C-RAS is as good as testing with traditional remedial action schemes. SISCO believes it has developed the sort of intensive, overlapping test procedures (for all systems and components) that will indeed prove that C-RAS will work better than traditional RAS.
Taking a holistic System Engineering approach, SCE expects the future C-RAS will provide a bird’s eye view of multiple events affecting the larger grid. These Smart Grid developments will open the door to new automation and control philosophies that can serve as broad safety nets to protect system reliability well beyond today’s reliability criteria limits.
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