AC and DC aggregation effects of small-scale wind generators

Abstract

Small-scale embedded generation (SSEG) has the potential to play an important part in the future UK generation mix. If a single SSEG is considered, its environmental, commercial and network operational value is low, but if a cluster of SSEGs are considered and their outputs aggregated they have the potential to be significantly more valuable. The aggregation of small-scale wind generators is considered. Each turbine is driven by a wind that is turbulent in nature and varies from location to location. The output from an individual turbine can be very variable, but when aggregated together with the power output from a number of turbines in the same locality, can produce a power output that is much less variable. The authors examine, by simulation, how the output from a number of small turbines can aggregate together to form a more consistent power output. Aggregation of the turbine outputs both after the power inverter, at alternating current (AC), and before the inverter, at direct current (DC), are examined. In both cases power variations are shown to reduce as the number of turbines connected increases. Aggregation at DC can lead to non-optimum performance of the turbine itself, if passive rectifiers are used, but can also lead to savings in the cost of the power conversion equipment required.