Energy Efficiency Impact on Demand

Recent news on the DOE secretary was about his speech at an energy forum attended by electric power industry stakeholders. The secretary was quoted to point at energy efficiency as a solution to the crisis in energy. He said if people would practice the Energy Efficiency Protocol,  the expected demand reduction will be 20% for residential load and 25% for industrial/commercial demand. If residential load is say 30% of the total grid demand then we can follow a formula like,

            TD_Eff = Res(0.8) + Ind(0.75) = (0.3)TD(0.8) + (0.7)TD(0.75) 

TD is the total demand and TD_Eff is the TD with energy efficiency at the demand side.

The DOE secretary also mentioned the energy savings from using energy efficient devices will solve the power shortage for three to four years. Following the DOE forecast on Visayas and applying the formula above, I wanted to verify the declaration.

Looking at the graph above, the DOE demand forecast is above the dependable generation capacity. When energy efficiency is accounted, the demand goes below the dependable capacity for the upcoming four years.

Does this solve the power shortage? No.

Grid operations require generation reserves to maintain system frequency and prepare for unforeseen grid contingencies. In real time, there are generation or transmission outages due to planned maintenance or forced outages.Visayas grid, as per NGCP website requires about 190MW for its generation reserves at the present time. Apparently, load will catch up with the generation capacity in 2013 based on DOE's projections.

Energy efficiency is good not only for the reduction of grid demand but also it makes the grid environment friendly. It will surely help, but given the situation, it does not solve the power shortage for the coming four years.

PS - At present, the dependable capacity in the Visayas alone is at 1,505 MW while peak demand is at 1,430 MW, with a required reserve margin of 335 MW.

Elektrisidad Pilipinas Cited at Philippine Online Chronicles

The work done on the approximate model of the Luzon power network and the rationale for its need was cited by the Philippine Online Chronicles. Below is an excerpt of the commentary where this blog was noted. 

Using the Approximate Luzon Network Model for Power Engineering Education and Training

Educators and trainers can utilize the model in lectures or laboratories for discussion of the following:

1.    Power flow analysis
2.    Application of grid code limits on branch thermal capacity and bus voltages with or without outages
3.    Application of N-1 contingency
4.    Determination of maximum generation of an area with or without N-1 contingency
5.    Determination of  the limiting contingency for dispatching maximum generation of a plant
6.    Determination of the maximum generation that can be interconnected to a specific bus without violating grid code limits on branch thermal capacity and bus voltages with or without N-1 contingency
7.    Determination of   how much load growth can be accommodated without transmission/generation expansion
8.    Determination of   the generation margin/reserves at peak and off peak conditions
9.    Impact of enabling on load transformer taps on bus voltages
10.    Impact of limited reactive power capacity of a certain plant on bus voltages
11.    Impact of outage(s) of 500kV line(s) on the system
12.    Impact of outage(s) of 500kV transformer(s) on the system
13.    Impact of load power factor of the system or of an area on the system performance
14.    Impact of power contract transactions on the system performance applying grid code limits
15.    Application of load forecast for Luzon in the coming years and determine needed generation and transmission expansion

There might be other applicable analysis depending on the capability of the software being used, in this case Powerworld.  Thus, the list above is not exhaustive.

Download the Approximate Luzon Network Model

I am providing a download link for the Approximate Luzon Network Model here.

Use it for good and noble purposes only. ;)

Developing the Approximate Luzon Network Model

Almost two weeks of vacation gave me enough reason to delay the update on the approximate Luzon power system model I have developed in Powerworld. In this post, I will cite the modeling assumptions I have made and some issues I encountered in the approximate model. The aim is to allow discussion to set in to refine the model as to depict as near as possible the real power system performance.

Component Modeling:

Generation:
I modeled the generation of an existing power plant as one lumped model. Data was taken from WESM Luzon single line diagram. For example, if Sual has two machines, the plant is modeled as one unit with the maximum capacity equals the sum of the Pmax of the units. The machines are assumed to operate at 0.95 power factor whether lagging or leading condition. If the dispatch is less than or equal the capacity of one unit, the reactive power must be adjusted too.

Transmission lines:
The line impedances were computed using the table of line parameters from page 68 of Power System Dynamics: Stability and Control book. The distances were determined with Google Earth. Application of plus 5 km. was considered to account for right of way instead of the straight distance measured.

Transformers:
The transformer capacities and voltage level were taken from the WESM single line diagram. The impedances were taken from the appendix of Elements of Power System Analysis book by Stevenson.

Load:
The load allocation at the buses was taken from the document posted at ERC. I added Zapote substation to further zoom into Metro Manila.

The issues I have encountered with this approximate model are:
1. The load power factor is an important parameter for voltage magnitudes. Low power factor will provide low voltages especially at highly loaded buses.

2. The assignment of swing bus brings a concern since two or more plants are lumped at one bus. The pick-up of needed supply or decreasing of output due to excess supply is shared by the plants connected at the swing bus and might cause unrealistic dispatch in real and reactive power.

Further improvement of the model can be the following:

• Validation with the real system performance - I do not know any public document that would give a snapshot of the Luzon grid at any load condition

• Plot the model with the Luzon map

• Include generation cost data

Email me at ebcano@gmail.com if you are interested to have the approximate Luzon network model. You have to download the Powerworld software for this.

Comments on the approximate model are very welcome.

Two things come into mind after I have completed this job - Visayas and Mindanao. ;)