Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-05-09T13:49:19Z No. of bitstreams: 1 Jéssica Cristina da Sousa Silva.pdf: 3803180 bytes, checksum: 09661347277c0b6b6dadfa09a5e05299 (MD5) / Made available in DSpace on 2017-05-09T13:49:19Z (GMT). No. of bitstreams: 1 Jéssica Cristina da Sousa Silva.pdf: 3803180 bytes, checksum: 09661347277c0b6b6dadfa09a5e05299 (MD5) Previous issue date: 2017-04-03 / FAPEMA / As a result of a contingency, severe overloads may occur in a power transformer. One of the greatest concerns of energy utilities is to find a way to operate this equipment that ensures its useful life is preserved. However, there is a sharp reduction in the useful life in proportion to the level of overload and this increases the risk of failure. This paper sets out a framework for decision-making in emergency operations for power transformers, that rely on interruption contracts as decision variables and which take into account the risk of accepting any level of violation of the transformer´s operating limits. The risk of failure is calculated by measuring the useful life of the transformer and the presence of dissolved gases. The useful life is estimated by means of the Arrhenius model of thermal damage , while incipient faults can be detected by Dissolved Gas Analysis (DGA). The risk of transformer failure is estimated by examining the data cited above, on the basis of information theory concepts. It is formulated as a multi-period optimization problem with linear objectives and nonlinear constraints and restricted to the risk of accepting transformer overloads. The results are validated by means of an adapted version of the IEEE14 system, which is shown to be effective as a tool for emergency decision-making in the case studies included here. / Como consequência de uma contingência, sobrecargas severas podem ocorrer em transformadores de potência. Uma das maiores preocupações das concessionárias de energia, é operar estes equipamentos de forma que a vida útil seja preservada. No entanto esta diminui drasticamente em proporção ao nível de sobrecarga aplicado além do aumento do risco de falha. Este trabalho apresenta uma estrutura para o auxílio na tomada de decissões de operação em emergência de transformadores de potência, utilizando como variáveis de decisão contratos de interrupção conjugados com a decisão de aceitar um nível de sobrecarga baseado no risco. São usados modelos térmicos de envelhecimento do transformador para cálculo de perda de vida. Para atualização da probabilidade do risco de falha, são utilizadas informações de Análise de Gases Dissolvidos (DGA) e da perda de vida útil do transformador combinadas através de conceitos de teoria da informação. Os resultados são validados usando uma versão adaptada do sistema IEEE 14, mostrado-se eficaz como ferramenta de tomada de decisões nos estudos de caso apresentados. Contratos de interrup¸c~ao, teoria da informa¸c~ao.

過去電力事業為了滿足電力用戶之需求，對於新電源之開發不遺餘力。然而由於電力事業近年來在供給面規劃屢遭當地居民抗爭而受阻，因而晚近轉而強調用戶需求面之管理。 本文針對台電公司現行需求面管理之「用戶計劃性減少用電措施」四種方案進行研析。首先設定簡化條件，將四種方案予以模型化，利用經濟剩餘模型，進行邊際分析，探討台電公司提供優惠之折扣比例及電力的價格需求彈性如何參與用戶抑低容量以及消費者剩餘、生產者剩餘分配之效果。分析結果顯示：「計劃性（二）」抑低用戶負載容量最高，且參與用戶之消費者剩餘最多；「計劃性（一）」抑低用戶負載容量最低，且參與用戶之消費者剩餘最少。另一方面，若從電力公司之視角觀之，「計劃性（二）」之生產者剩餘最低，而「計劃性（一）」之生產者剩餘最高。 經濟剩餘模型分析中，由於未能充分考慮供需雙方之潛在成本與效益，因此實務上之解釋能力有其侷限之處。基於上述緣由，本文接著藉由成本效益分析，將方案實施之潛在成本與效益納入考量，分別從參與用戶之角度進行參與者檢定（Participant Cost Test, PCT）以及從電力公司之角度進行公用事業成本檢定（Utility Cost Test, UCT），以檢視不同方案在不同觀點下之績效表現。成本效益分析結果顯示：在PCT檢定下，「計劃性（四）」參與用戶之益本比最高，「計劃性（二）」參與用戶之益本比最低。而在UCT檢定下，「計劃性（一）」電力公司益本比最高，「計劃性（四）」電力公司益本比最低。將成本效益分析與經濟剩餘模型比較後可發現，用戶抑低容量高的方案對於電力公司而言未必最有利。 最後，為進一步探討關鍵變數變動造成不同方案間成本效益值之影響，因此進行敏感度分析。敏感度分析的結果顯示：若電力公司為吸引用戶而提高誘因，增加各方案給予用戶優惠折扣之比例，以參與用戶角度而言，「計劃性（四）」參與者檢定之益本比提高幅度最大；以電力公司角度而言，「計劃性（四）」公用事業成本檢定之益本比降低幅度最大。若電力公司提高參與用戶每次抑低用電負載之時數，以參與用戶角度而言，「計劃性（四）」參與者檢定之益本比降低幅度最大；以電力公司角度而言，「計劃性（四）」之公用事業成本檢定益本比提高幅度最大。 / In order to meet the users’ demand of electricity, the electric power utility spared no effort to develop the new power plant in the past. However, in recent years, the electric power utility have been hampered by local residents on supply-side planning, thus more emphasize is being put on users’ demand-side management（DSM）. This paper aims to analyze four projects of Taipower’s existing demand-side management of “incentive plan for customers’ scheduled load curtailment program”. First, we set several simplified conditions for modeling the projects. By using the economic surplus model and conducting the marginal analysis, the impact from the discount incentive provided by the utility and the elasticity of electricity price demand is explored－on participants’ load capacity reduction and the distribution of consumer surplus and producer surplus. The results of economic surplus model showed "project 2" curtails the maximum load capacity and with the highest consumer surplus; "project 1" curtails the minimum load capacity and with the lowest consumer surplus. On the other hand, in the Taipower's point of view, "project 2" provides with the lowest producer surplus while "project 1" gives the highest producer surplus. In the economic surplus model, since the potential costs and benefit were not fully considered in both supply and demand sides, several limitations exist on this model. Based on the above reasons, we utilize the cost benefit analysis, taking the potential cost and benefit into account and conducting Participant Cost Test（PCT） from the participants’ perspective and Utility Cost Test（UCT）from the utility’s perspective to examine the performance under different 4 DSM projects in different point of view. The results of cost benefit analysis showed that in the PCT test, the "project 4" comes up with the highest benefit cost ratio while "project 2" has the lowest cost benefit ratio. In the UCT test, the "project 1" has the highest cost benefit ratio while "project 4" came with the lowest cost benefit ratio. Comparing the cost benefit analysis with the economic surplus model, we could find that the project with the most load capacity reduction may not be the most favorable project for the utility. Finally, in order to further explore the key variables affecting the cost and benefit value in different projects, we simulated several scenarios for sensitivity analysis. The results of the sensitivity analysis showed that if the utility increases incentives to increase four projects’ ratio of discount for attracting participant, in the participants’ perspective, "project 4" would have the most changed rate of cost benefit ratio（increase）; in the utility's perspective, "project 4" would have the highest adjusted rate of cost benefit ratio（decrease）. If the utility increases the load curtailment duration each time, in the participants’ perspective, "project4" would have the highest adjusted rate of cost benefit ratio（decrease） ; in the utility’s perspective, " project4 " would have the highest adjusted rate of cost benefit ratio（increase）.