Assignment Introduction to Electricity Markets

Problem 1

For the circuit below, what is the total equivalent resistance between the terminals of the voltage source? Show your work.

Problem 2

For the simple circuit shown below:

a. What is the current i₁? Which of Kirchhoff's Laws do you use to find this?

b. What is the current i₁? Which of Kirchhoff's Laws do you use to find this?

c. Use Ohm's Law to find the voltage drop across the resistor.

d. What is the voltage v₀ provided by the 1.5A current source? Which of Kirchhoff's Laws do you use to find this?

e. What is the power dissipated by the resistor?

Problem 3

A toaster oven has a resistance of 24 ohms. At a voltage of 120 V, what is the current through the toaster, and how many watts of power does it draw? How many kilowatt-hours of electric energy does this toaster oven consume in a 30-day month, if it operates for 20 minutes every day?

Problem 4

Rumor has it that some time back in the 1980s, some European utility companies were accused of trying to increase their revenue by simply raising the service voltage for unsuspecting customers by a few percent. For example, instead of supplying 220 V as expected at the customer service drop, they might have supplied 230 V instead. In general terms (using equations for voltage, current and power), explain why the utility might expect to sell more kWh of electric energy if the service voltage were raised.

Problem 5

The circuit shown in the figure below has one generator and one customer ("load"). Assume that the generator produces 100 MW of power.

a) Calculate the power flows (flow rates, actually) along each of the two transmission lines. (Note: the flows should take units of MW. Don't forget to include the units in your answer!)

b) Repeat part a), but assume that the resistance of Line 1 is 2R, and the resistance of Line 2 is 3R.

Problem 6

In the three-­-node network shown in the figure below, two of the lines have resistance R and one of the lines has resistance 2R.

a) Suppose that Generator 1 produces 10 MW of power, while Generator 2 produces 30 MW of power. All of the power is consumed by the load (customer) at Node 3. Calculate the flows (in MW) across all three transmission lines. You may ignore transmission losses in your calculations.

b) Repeat part a), but assume that Generator 2 produces 50 MW of power.