Analysis of electric energy storage technologies

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Faludi Andor
Department of Electric Power Engineering

Both daily and annually, there is an observable continuous change in Hungary’s power demand (energy consumption): in the night the consumption is less than daytime. Annually, the load is higher in the winter because of the amount of energy used for lighting and heating in the temperate zone; in the summer, when there is no need for heating and as much light, the consumer’s power demand is less, though the widespread use of the air-conditioning systems makes this energy gap smaller and makes the peak period change.

The consumers’ power demand can be satisfied by changing the power plants’ generation level. It is only applicable between certain limits and this phenomenon is called system control. However, for the system operator, the availability of this option is limited: since the generation level of traditional power plants can only be changed slowly, their run-up and shutdown processes can even last 6-8 hours which is considered to be a relatively long time for the system (just like in the case of coal-fired power plants, which use steam generators and turbines to generate electricity).

The amount of electricity generated from renewable sources, typically from wind and sun, is not certainly predictable, since the amount of wind can only be estimated and the number of sunny hours is not foreseeable with full certainty. Consequently, the generation level of electricity can rapidly change which raises difficulties for the transmission system operator, moreover, the wind and solar power plants are regulable only to one direction. At present, if the generation level of the wind or solar power plants are different from scheduled, the difference needs to be regulated by traditional power plants.

Worldwide, there are two ways to handle these problems. One of them would be setting up power plants which can be rapidly run up and shut down. The other one would be installing energy storage.

In this study I compare the electricity energy storage technologies and their fields of application. When installing a storage device, one needs to examine which voltage level it can be connected to and what kind of disturbances and distortions can occur. In the same way, the ways for making use of the chosen technology and for making profit of it within the framework of law is important for the operator. There are many options for integrating the device into control in the controlling area of the Hungarian Transmission System Operator. Probably, there are necessary modifications in the IT systems provided for the balancing and ancillary services by the TSO depending on which kind of regulation would the device be integrated to.

Not only is it making profit for the operator of the device, but the end users of the system also can benefit of the better quality of the energy supply if the operation is based on an adequate model.


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