Wind Energy Integration Methodology and Results
A methodology has been developed to quantify the technical and operational potential for integrating wind power. The methodology uses a "top down" analysis whereby the essential volumes of generation required to operate (e.g. to provide the ancillary services of frequency reserves and instantaneous reserves) are subtracted from the generation required in a given half hour. The methodology aims to subtract all essential generation, with the remaining non-specific generation being the potential limit to wind integration.
It is noted here that this methodology only assesses technical and operational issues, not other factors such as the relative economics of wind versus other generation. Furthermore, this is a projected wind integration limit that could only be approached in the longer term. This is because investment in wind-based generation is unlikely to replace existing generation, but could make significant contributions to meeting ongoing growth in electricity demand.
Our hypothetical analysis used the forecast lowest generation for 2005 in each of the South and North Islands. The current year was chosen because the mix of generation is already known, thus not requiring modelling or estimation of generation growth scenarios for years further into the future.
From each generation figure was subtracted an allowance for conventional generation plant that would have to run:
- to perform fine control of frequency in the range from 49.8 Hz to 50.2 Hz;
- to be on standby in the event of frequency suddenly falling below the normal operating range;
- to maintain safe voltage levels on the grid;
- to make up for very short term swings in output of wind farms;
- to ensure that adequate generating plant is available to operate, if required, in a few hours time or even tomorrow.
The result of the analysis was penetration of about 35% and market share of 20%, based only on technical and operational issues.
These initial wind integration estimates are reliant on these key assumptions:
- that future wind farms will consist of modern wind turbine generators which can provide grid support capabilities similar to those of conventional generators;
- that wind farms will be geographically dispersed rather than clustered in one region; and
- that wind speeds can be forecast with sufficient accuracy up to the end of the next day.
A high level of wind penetration is by no means assured, not least because wind competes with other equally viable types of more conventional generation. Nevertheless, this initial analysis indicates that advancements in wind turbine generator technology have the potential to support much higher levels of wind integration than we currently have, quite possibly to the point of being comparable with countries which currently lead the world in wind energy. This possibility places challenges in front of the electricity supply industry.
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