Preferred TVC model: 'The price elasticity beta is now estimated to have the expected negative sign in all sectors' (p.342); 'The more flexible models with a time-varying long-run relationship ... clearly dominate the fixed-coefficient models in every dimension of comparison' (p.345).
Chang, Y., Kim, C. S., Miller, J. I., Park, J. Y., & Park, S. (2014): 'Time-varying long-run income and output elasticities of electricity demand with an application to Korea.' Energy Economics, 46, 334-347.