It was known from the start that wind inputs power inputs to the grid would be intermittent but there was an expectation that the supply would become more even as more capacity was built
In 2012, when the installed capacity was 2GW, Paul Miskelly published the first major analysis of the system and he warned that the problem of wind droughts and rapid fluctuations in the wind supply might not be mitigated in the course of time. The reason is that high pressure systems cause the lows and they can sit across the whole of the SE for many hours and sometimes days.
John Morgan’s study in 2015 with 4GW of installed capacity supported Miskelly’s findings.
Mike O’Ceirin studied all the low-wind periods from 2011 to 2020 and found that prolonged wind droughts across the whole of SE Australia (the National Electricity Market) persisted with 8GW of installed capacity. Outage YYYY V2 (1)
The spreadsheets indicate the periods when the output was 10% or less of the installed capacity. They show the duration of the low wind periods (33 hours max in 2020) and the the average supply during the period (6% in that case). The data cover the years 2011 to 2020.
Recently “Tony from Oz”, a long-term wind-watcher and commentator released some detailed studies of fluctuations in the wind supply.
The most important observation.
Over the relatively two years of the study, significant falls in the supply of wind power, equivalent to the size of a typical coal-fired generator, became more prevalent, larger in size and the power loss occurred more quickly.
Frequent outages of coal-fired turbines would be regarded as a serious scandal and receive headline treatment in the media. Similar falls in the wind system pass without comment.
The data come from the continuous record of output from all the registered generators that is kept by the Australian Energy Market Operator. Each wind farm is registered as a generator, likewise the individual generators, often four in number, in coal-fired power stations.
The observations cover 800 days from May 2018 to the end of June 2020
The number of short-term falls of 500MW or more were counted in periods of one hour or less and in one to three hours. A separate report covered larger falls over longer periods.
The 500MW figure corresponds to the most common capacity of coal-fired generators, so the fall of 500MW can be compared with the impact of a coal-fired generator going off line.
The situation got worse rather that better over the period of analysis, contra to the hopes and expectations of the industry.