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DEA and Electricity Distribution Networks in Portugal. Júlia Boucinha*, Célia Godinho, Catarina Féteira Inácio, Tom Weyman-Jones September 2003. Why does EDP Distribuição use benchmarking? for management decisions;
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DEA and Electricity Distribution Networks in Portugal Júlia Boucinha*, Célia Godinho, Catarina Féteira Inácio, Tom Weyman-Jones September 2003
Why does EDP Distribuição use benchmarking? for management decisions; to provide better customer service since EDP Distribuição is public utility; to respond to incentive regulations based on price capping. EDP Distribuição Networks 2
Background • Electricity Distribution company covering the whole of the Portuguese Mainland and, hence, the number of clients is related to the whole population • Efficiency studies started to try and evaluate the company’s performance in comparison with other european utilities – beeing the only operator in the country, comparisons have to be made with foreign companies • More recently, DEA method has been applied to measure the efficiency of the different networks areas, within the company • Network areas are regional business units, with some autonomy 3
Why choose DEA? • DEA (data envelopment analysis) • many models (including returns to scale) without mathematical specification of technology; • clear interpretation of results: % efficiency; • ability to penalise networks with slack in input use and output production; • but data must be accurate, without serious measurement error: consistently monitored by EDP Distribuição; • must allow for uncontrollable factors, characteristics of operating environment. 6
DEA model • Objective penalises slack variables in measure of % technical • efficiency: q find network we ights to : ( ( ) ) q - e min slacks å such that for each output and input : ( ) ´ network output network we ight å ( ) ³ network output network being measured ( ) ´ network input network we ight å ( ) £ q network input network being measured ³ all network we ights 0 7
INPUTS - anything on which money is spent: Economic models use “inputs” in physical sense: labour, capital Company data uses financial equivalents: OPEX, CAPEX, … This study concentrates on OPEX only Benchmarking data: 1 8
OUTPUTS – anything customers would pay for if necessary: Economic models use “outputs” with market or shadow prices: energy, service, network connection Company data may measure these approximately: kWh, number of customers, network length Benchmarking data: 2 9
OPERATING CHARACTERISTICS:anything that cannot be controlled by the management In the short run, for example: customer density underground/overhead lines market share of high and low voltage demand Benchmarking data: 3 10
Input: OPEX Outputs: energy delivered, customers, lines Try all subsets of outputs Compare variable returns to scale Add non-discretionary variables to measure operating characteristics customer density, low voltage connections, underground networks Add quality of supply if possible Is there still a network with some inefficiency - how much? Modelling strategy: 1 11
Experiment with variable returns to scale Experiment with new variables to represent operating characteristics Each experiment adds 1 or more constraints to envelopment model Therefore cannot make efficiency score of any network lower Modelling strategy: 2 12
Frontier for one input and two outputs Input: OPEX Outputs: Lines, Energy 16
DEA - Model Results: Input: OPEX Outputs: Lines, Energy and Customers 17
Non - controllable variables • Outputs • Customer density (area per client) - reflects the difficulty in reaching clients, in some networks areas • Share of underground lines – network areas with a bigger share of underground lines bear higher costs • Percentage of LV energy on the total - reflects different cost levels • Inputs • Lost load - measure for the impact of Quality of Sevice in network efficiency, considered as an input, since it reflects a negative output 18
DEA - Model Results: Inputs: OPEX Outputs: Customers, Energy, Lines, Customer density, Underground Lines/Total, LV Energy/Total 18% 19% 1% 20% 19
DEA - Final model results: Inputs: OPEX, Lost Load Outputs: Customers, Energy, Lines, Customer density, Underground Lines/Total, LV Energy/Total 18% 19% 1% 20% 20
DEA (VRS) - 2002 vs. 2001 Inputs: OPEX, Lost Load Outputs: Customers, Energy, Lines, Customer density, Underground Lines/Total, LV Energy/Total 18% 29% 19% 34% 1% 20% 20% 6% 23
Conclusion Network areas efficiency analysis • Shows the priority areas for management improvement • Leading to measures to reduce innefficiencies • In general, we have an improvement in the efficiency levels of the less efficient network areas 24
Slacks based measurement recent development,Tone (2001) computes new efficiency measure based on slack variables: % efficiency = [reduction in inputs relative to sample]/[expansion of outputs relative to sample] gives more discrimination amongst small sample of networks Directions for future work? 25