Customer Value and Profitability of Power Transformer Online DGA Monitoring
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Asiakasarvo ja kannattavuus tehomuuntajien reaaliaikaiselle vikakaasumonitoroinnille
This Master thesis defines the profitability for power transformer online dissolved gas analysis (DGA) monitor. The thesis studies the condition monitoring practices, decision making processes and the customer value of the online DGA monitor with different customers. It covers four different customer types: power plants, transmission system operators, distribution system operators and industrial factories. The research problems were studied by getting statistical information about power transformer failures, their effects and caused costs by interviews and literature. To define the customer value of the online DGA monitor, the efficiency to recognize evolving failures was compared to already existing methods. The actual investment profitability was evaluated by calculating the internal rate of return and payback period. For these methods, the cash flow analysis from the costs and benefits of the DGA monitor was made. The results were, that the online DGA monitor recognizes the evolving failures with the efficiency of 90 % while the number without it is 50 %. The internal rate of return was positive with all the customer types. However, for distribution system operators it was less than 10 % which can be interpreted as questionable while with other customer types the corresponding number was more than 10 % which can be evaluated as profitable. Also the payback period of distribution system operators is questionable with 4-10 years while with the other customer types it was profitable with the corresponding number less than 4 years. As a conclusion, it was stated that the direct savings from automated condition monitoring are not enough to justify the online DGA monitoring investment. Instead, the customer value of the indirect cost savings is the greatest with power plants and industrial factories while with the transmission and distribution system operators the corresponding numbers are weak. The poor profitability with indirect cost savings with transmission system operators is due to the N-1 criterion which, in practice, prevents the transmission outages. In these situations, the greatest value for online monitoring is that most of the expensive failures can be recognized and converted into minor maintenance activities. The relatively low price and the good availability of the distribution power transformers are the reason why online DGA monitoring is not profitable for them. The role of the insurance companies is not significant, what it comes to online DGA monitoring. The deductibles are higher than the price of the online DGA unit, so the monitoring can be seen as profitable despite the insurances.