UNIT23 LECTURE6:
Generation Planning
The electric utility planning process begins with the electricity load-demand forecast. The demand for electricity initiates actions by utilities to add generation, transmission, or distribution capacity. Because of the long lead time required to construct new facilities, decisions are often to be made 2 to 10 years in advance.
A load forecast was developed for the Kingdom and the results are presented in the following sections covering the study period 2008 to 2023. Load forecasts are developed for all SEC operating areas.
The methodology and the basis of development of demand forecast are highlighted below:
●Multiple regression analysis is used to forecast the Energy for the KSA.
●Independent variables are chosen to be the population and the Gross Domestic Product (GDP).
●The dependent variable is the Energy forecast for KSA.
●The data for the historical and the forecasted GDP has been obtained from the Ministry of
Planning.
The forecast for the total sold energy for the Kingdom was obtained using the regression model. The total sold energy was then divided between the four operating areas using historical value of percentage energy sales for each operating areas. This gives the total sold energy forecast for each of the operating areas.
Peak Demand is calculated using the equation
Forecasted Peak Demand in Region= Forecasted Energy in Region/8760*Load Factor.
Co-Generation/ Captive Power
Captive power plants are associated with specific industrial complexes, and their output is almost entirely consumed by that industrial plant. Another term that may sometimes be synonymous is 'cogeneration' in which the power plant produces multiple forms of energy (e.g., electric power and steam), and where both are raw-materials for a related industrial process. Probably the most classic example is that of a paper mill. Boilers produce steam. The steam passes through a turbine that spins a generator to produce electricity. Exhaust steam from the turbine is then used as a source of heat to dry freshly-made paper before is is finally condensed into water and returned to the boiler. The boiler itself burns the bark that itself cannot be used to make paper and would otherwise be a waste material. In addition, the process of making pulp produces a chemical waste called "black liquor' that can also be burned as a fuel in a boiler.
Captive power plants don't necessarily have to be islands that are disconnected from 'the grid'. In fact, it is often the case that the demand of the industrial process exceeds the capacity of the captive plant, and power must be taken from the grid to make up the difference. Also, there must be some provision to 'bootstrap' the integrated process into operation - often this means relying
on grid power to start-up the plant following an outage. And it is possible that there are times when the captive plant will produce more power than can be consumed in the industrial process, and rather than throttle back the excess is sold to the grid.