Generation and transmission adequacy evaluation of power systems with wind generation

Abstract

In response to the challenge of proposed reductions to greenhouse gas emissions outlined in international agreements such as the Kyoto Protocol, countries are considering supplying a significant share of their future energy requirements from renewable energy sources. Wind power, both on and offshore, is the principal commercially available and scaleable renewable energy technology. It is expected to remain the dominant technology in the medium-term future by delivering the majority of the required growth in renewable energy. The unique characteristics of wind power generation raise issues for its integration into the existing power systems. This thesis explores three specific issues, namely, wind generation’s limited capacity value, its remoteness from demand centres and the appropriateness of the regulatory framework governing its integration. The first issue was addressed by examining how the presence of flexible generation sources like hydro power affects the capacity value of wind in an assessment of overall system generation capacity. Wind capacity credit is interpreted from a planning perspective, and also as a component of the economic value of wind. The results illustrate that hydro power can compensate the variability of wind generation thereby augmenting its capacity value. The second issue required the development of a transmission planning methodology to evaluate the sufficiency of transmission network capacity to accommodate wind generation and to manage security of supply. The methodology was used to assess, over the long term investment horizon, the requirement for additional transmission network capacity driven by wind generation. The assessment found that wind generation drives less transmission network capacity than conventional generation and that wind and conventional generation should share the same transmission network capacity. Finally, the thesis looked into the establishment of regulatory framework that could recognise the realistic contribution of wind generation characteristics to transmission security and capture this contribution within the network pricing structure. The current 4 transmission security standards were reviewed to evaluate whether they are capable of recognising the different operation characteristics and output of wind generation. Standards for assessing transmission adequacy were found to lead to under-investment in capacity for importing areas and over-investment in exporting areas. Consequently, a set of ‘contribution factors’ capturing the interaction between wind and system characteristics were derived to augment the standards. At the same time, a modification of the present TNUoS charging mechanism in order to discriminate between generation technology types and to devise cost-reflective pricing regimes is proposed. This is particularly important when transmission investment is driven by reliability, as in exporting areas the cost reflective charges for wind were uniformly found to be lower than the charges for conventional generators.