Calculation of the power term in three-period electricity tariffs

Abstract

Interactive simulation in Matlab of the payment for contracted power and maximum power consumed in a load curve with a three-period tariff. In electricity rates with three periods (such as 3.0A or 3.1A), the payment to be made in the power term reflects the cost of the contracted power and the maximum power demand in a given rate period. The price of kW is defined in the contract, nevertheless, the amount to be paid from one month to another can be very different. What does this difference depend on? Actually, the cost of this concept of the invoice is calculated by multiplying the price of the kW established in the contract for each period by the billable power. Thus, there are three possibilities depending on the monthly demand for each period. 1.- If the maximum average quarter-hourly demand of the month, in a given period, is less than 85% of the contracted power, the billable power is 85% of the contracted power for that period. 2.- If the maximum average quarter-hourly of the month, in a certain period, is between 85% and 105% of the contracted power, the billable power is exactly the maximum power demanded in that period. 3.- Finally, if 105% of the contracted power is exceeded in a period, there is a significant surcharge on the bill, since the billable power is calculated as the maximum power demanded plus twice the difference between this value and 105% of the maximum power contracted in said period. In this laboratory, various demand profiles for a real day of buildings in the tertiary sector have been included to analyze what happens in each of the two seasons of the year (winter time and summer time), depending on the maximum demanded power, the contracted powers and the prices of the power in each period.