87th AMS Annual Meeting

Tuesday, 16 January 2007: 5:00 PM
Space Weather and the Incidence of Reactive "Off-Cost" Operations in the PJM Power Grid
210A (Henry B. Gonzalez Convention Center)
Kevin F. Forbes, Catholic Univ., Washington, DC; and C. St Cyr
Poster PDF (345.3 kB)
PJM Interconnection is a regional transmission organization (RTO) that as of 30 April 2004 coordinated the dispatch of 76,000 megawatts (MW) of generating capacity over 20,000 miles of transmission lines in all or parts of Delaware, Maryland, New Jersey, Ohio, Pennsylvania, Virginia, West Virginia and the District of Columbia (PJM, 2004). Forbes and St. Cyr (2004) have provided empirical evidence that adverse space weather conditions have affected the price of electricity in the PJM power grid. In this paper we examine one of the mechanisms by which space weather impacts the electricity market. The starting point is that there are two types of power on alternating current systems: real power and reactive power (Sauer, 2003). Real power is the power that consumers need to light their lamps and run their computers and refrigerators. In contrast, reactive power maintains the voltages required for system stability and thus is critical to the delivery of real power to consumers. With respect to space weather, it is well-known that there is an increase in reactive power consumption when GICs pass through a transformer (Kappenman, 2003, p. 4).

Generators in PJM are dispatched based on their cost with the lowest cost generators being dispatched first. One exception to this is when reactive power conditions warrant an “out of economic merit” order dispatch. In PJM, this is known as a reactive “off-cost” operation (PJM, 2005). In this paper, we examine the effect of GICs on the incidence of these reactive “off-cost” operations in PJM using an econometric model. Previous literature has indicated that GIC levels in power grids are closely related to the time derivative of the horizontal component of the geomagnetic field (Bolduc et al. 1998; Coles et al., 1992; Mäkinen , 1993; Viljanen, 1997). Accordingly, GICs in this study are proxied by dH/dt based on local magnetometer data. The econometric model also takes into account the other factors that are believed to contribute to these events.

The analysis also demonstrates that the results of that study are robust by substituting the dH/dt measurements from the geomagnetic observatory closest to PJM with dH/dt measurements from other locations around the world. Finally, the paper estimates the market impact of the reactive “off-cost” operations using a second econometric model.


Bolduc, L., Langlois, P., Boteler, D., and Pirjola, R., 1998, A study of geoelectromagnetic disturbances in Quebec, 1. General results, IEEE Trans. Power Delivery, 13, 1251–1256.

Coles, R. L., Thompson, K., and Jansen van Beek, G., 1992, A comparison between the rate of change of the geomagnetic field and geomagnetically induced currents in a power transmission system, Proc. EPRI Conf. Geomagnetically Induced Currents, Burlingame, Ca., 8–10 Nov. 1989, EPRI TR-100450, 15, 1–8.

Forbes, K. F., and O. C. St. Cyr, 2004, Space Weather and the Electricity Market: An Initial Assessment, The Space Weather Journal, 2, SW100003,doi:1029/2003SW000005.

Kappenman, John, 2003, “The Vulnerability of the US Electric Power Grid to Space Weather and the Role of Space Weather Forecasting,” Prepared Testimony before U.S. House Subcommittee on Environment, Technology & Standards Subcommittee Hearing on “What is Space Weather and Who Should Forecast It?”

Mäkinen, T., 1993, Geomagnetically induced currents in the Finnish power transmission system, Finn. Meteorol. Inst. Geophys. Publ., 32.

PJM, July 2005, PJM 101 Glossary. Available on the Internet at http://www.pjm.com/services/training/downloads/20050712-pjm-101-glossary.pdf

PJM, May 1 2004, Press Release, Commonwealth Edison Successfully Integrated into PJM

Sauer, Peter W., 2003, “What is Reactive Power?” Power Systems Engineering Research Center, Department of Electrical and Computer Engineering, University of Illinois at Urbana- Champaign.

Viljanen, A., 1997, “The relation between geomagnetic variations and their time derivatives and implications for estimation of induction risks,” Geophys. Res. Lett., 24, 631–634.

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