Large Amounts Of Wind Generation Research Articles

Automatic under-frequency load shedding mal-operation in power systems with high wind power penetration

Countries with a limited interconnection capacity suffer substantial frequency variations after large incidents so they use automatic under-frequency load shedding schemes to arrest the frequency decay. Some of these countries such as Portugal, Spain and Ireland also have very high wind penetrations. This can cause additional frequency excursions due to generation time variability but also to the fact that variable speed wind turbines do not add directly their inertia to the power system. Thus several transmission system operators have announced new grid codes requiring wind turbines to provide frequency response.In some scenarios, however, wind energy support may be detrimental to frequency control because it generates an extra energy that reduces decay and derivative but that cannot be maintained over time. These lower values of frequency decay and derivative are currently expected after a reduced incident or when conventional generation, which can maintain the extra generation, provides frequency support, so lead to low or no load shedding. This paper has studied, in particular, the effect of wind generation emulating inertia. A reduction of frequency derivative is achieved, which looks positive at first, but in some cases leads to initial smaller load shedding than the incident requires. A reduced frequency derivative triggers less under-frequency relays as if there were a significant amount of conventional generation that is online. However, this generation has been substituted by wind generation emulating inertia, and as it can maintain extra generation over time, the frequency continues to decay until the shedding of the next load step. As a result there is an excessive frequency deviation and an incorrect load shedding for the magnitude of the initial disturbance. In order to prevent this problem, automatic under frequency load shedding settings may need readjustment when a large amount of wind generation provides frequency support.

Renewable Energy Interconnection and Compliance—An Australian Perspective

Large amount of wind generation is likely to be installed in Australia in coming years. In the current climate change and environment, wind energy will not only be able to contribute to securing Australian energy independence and climate goals in the future but also it could also turn a serious energy supply problem into an opportunity in the form of commercial benefits, technology research, export and employment. Due to the ever increasing integration of this renewable energy, the transfer capability has been a major concern. The main purpose of this study is to assess the transfer stability analysis of impact of wind turbine technology connected to weak power system and short transmission distance with various demand conditions when wind turbine with ZPM connected at transmission network level and its compliance to National Electricity Rule (NER). PSS/E software has been used for the study which accurately simulate the power system and wind turbine. NER compliance has been used as an example to test Grid compliance. The fault ride-through requirement for wind energy converters has also been a common practice as conventional power plants. Therefore various system faults have been simulated to see the impact of renewable on the system. Studies show that for all faults under most scenarios, the system remains stable and well damped, i.e. oscillations are damped to 50% within 5 seconds. Even for the most severe fault with 230kV line cleared by circuit breaker protection by tripping all the lines connected to 230kV bus, the system remains stable and well damped.

How does market power affect the impact of large scale wind investment in 'energy only' wholesale electricity markets?

In the short run, it is well known that increasing wind penetration is likely to reduce spot market electricity prices due to the merit order effect. The long run effect is less clear because there will be a change in new capacity investment in response to the wind penetration. In this paper we examine the interaction between capacity investment, wind penetration and market power by first using a least-cost generation expansion model to simulate capacity investment with increasing amounts of wind generation, and then using a computer agent-based model to predict electricity prices in the presence of market power. We find the degree to which firms are able to exercise market power depends critically on the ratio of capacity to peak demand. For our preferred long run generation scenario we show market power increases for some periods as wind penetration increases however the merit order counteracts this with the results that prices overall remain flat. Returns to peakers increase significantly as wind penetration increases. The market power in turn leads to inefficient dispatch which is exacerbated with large amounts of wind generation.

Impact of a large penetration of wind generation on the GB gas network

Wind power is expected to be the major element of renewable electricity generation in Great Britain (GB) by 2020 with a capacity of around 30 GW. The potential impact of a large amount of wind generation on the GB gas network was investigated using a combined gas and electricity network model. The varying nature of gas and electric power flows, network support facilities such as gas storage and compressors, and the power ramping characteristics of various power plants were considered. Three case studies were modelled, one case uses the existing network and the other two make use of a hypothesised network in 2020 with two distinct levels of wind generation representing low and high wind periods. The simulation results show that a large penetration of wind generation will influence the electricity generation mix as the wind power varies. Gas-fired generation is used to compensate for wind variability. This will cause increased flows and compressor power consumption on the gas network. Linepack depletion during low wind periods was shown to limit the ability of the gas network to fully supply gas-fired generators.