New Technology Instead of New Transmission?

Transmission owners and the grid operator are looking into new technologies to push more power through the system and extend the grid?s life. ?It buys you time,? said Dave Hawkins, California Independent System Operator (CAISO) principal engineer. ?The question is, how much time? We?re trying to stretch existing assets a little more.? The grid operator is focusing on three end uses of new technology, said Hawkins?to understand what?s going on thermally with transmission lines so they don?t sag; to understand what?s going on with voltage so it doesn?t collapse; and to figure out how much the system is oscillating so it doesn?t become unstable. The technology closest to being embraced is a device that monitors individual transmission lines to determine optimal capacity and breaking points. Transmission lines do not have static throughput because their capacity fluctuates with the weather. A high-tech application being considered by CAISO is a computer program that scans the grid?s data points 30 times per second?up from the current scan every four seconds. CAISO is also considering a technology that?s been around for decades, but with no widespread use?an electricity storage device, the flywheel. While it?s a matter of physics that electricity cannot be stored, a flywheel does a short-term version of ?storage.? Basically, a motor spins the flywheel, which then stores the kinetic energy. Flywheel storage to boost stability looks promising to CAISO engineers. Missing from the grid radar are much-hyped superconductors: while most have heard of the promise of superconducting materials, time testing has not lived up to expectations. CAISO dismisses the much-ballyhooed superconducting technology. ?On the cable side, it?s years off,? said Hawkins. ?We are monitoring [experiments] only.? Superconducting materials, such as niobium-titanium in liquid helium, are being researched to find whether a transmission line using small-diameter wires and low voltage could be built with zero energy losses. Determining dynamic load ratings on transmission lines employs new gadgets to figure out rather mundane information?whether and how much a line is sagging in between checkpoints. The gadgets, called CAT-1 monitoring systems, are being field tested. The Western Area Power Administration (WAPA) has been using them for two years. Pacific Gas & Electric also has them along Path 15. The devices are put at two ends of high-voltage wires?typically in the same bioregion. For example, they could be as far apart as either end of the Central Valley, or as close as either end of the San Francisco peninsula. Currently, without the devices, the grid operator estimates how much electricity a line can transport, and does so conservatively. With monitoring devices measuring the sag of a wire, the grid operator could squeeze another 10 to 15 percent of capacity out of a line that is cool. But if the line is hotter than estimated, engineers might have to derate the line, according to Hawkins. Currently, WAPA collects data on the overload point on four lines in the Sacramento area. ?We want to make sure we?re in the clear? so they don?t get overburdened, said Morteza Sabet, WAPA manager of transmission planning. The next step is to use the data to push as many megawatts as reasonable through the system. ?The results are very encouraging,? he added. CAISO does not estimate the costs for transmission owners to install the devices, but WAPA said that because it is exploring them through the California Energy Commission?s subsidy program, the cost would be under $250,000. A computer program that would accelerate the current data scan for the grid operator?s 80,000 data points could give operators a better picture of the system and avoid unusual blackouts, like the one last year in New York, according to Hawkins. With the software, monitors could see oscillation patterns in the system and check them against typical patterns. This system, said Hawkins, would work with an automatic control device to ramp generation up or down ?so we get to the point where we don?t depend on an operator? and the associated time involved with manual system adjustments, such as the old-fashioned phone call. Hawkins expects CAISO could distribute clusters of 20 MW flywheels. Each occupies a space the size of a cargo ship container and can be used to stabilize system frequency. He said that with a batch of flywheels, the grid operator could add 100 MW to the system with a one-second ramp-up time.

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New Technology Instead of New Transmission?

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