Use of Power Guide Curve Rule in HEC-ResSim

In this post, I have developed a simple reservoir network with one reservoir.  The schematic is shown below.

This reservoir has a powerplant with the following characteristics:

Hydraulic capacity = 500 cfs
Installed capacity = 2 MW
Efficiency is a constant 80%
Constant tailwater of 25 ft

The installed capacity tab of the power plant is shown below.

The following top of zone elevations are used in the operations set.  They are constant throughout the entire year.  

Top of flood = 100 ft

Top of conservation = 75 ft

Top of inactive = 50 ft

These are shown in the figure below.

For this example, a Power Guide Curve Rule is used.  This rule specifies that the power pool is from the top of conservation (75 ft) to the top of inactive (50 ft).  The rule is shown below.  A plant factor of 50% is specified when 0.0% to 49.999% of the power pool is in use.  A plant factor of 100% is specified when 50.0% to 100.0% of the power pool is in use. 

The plant factor specifies how much of the installed capacity is to be used.  So, a plant factor of 50% in our example will be 1 MW while a plant factor of 100% will be 2 MW. 

To understand the results provided below, a review of the power equation is needed.

Power in MW = (Q*w*h*e) / 737,560

where Q is in cfs, w is in lb/ft^3, and h is in feet

So, at the top of conservation, with the maximum hydraulic capacity being utilized, the generation amount will be as follows:

MW = (500*62.4*(75-25)*.8) / 737,560 = 1.69 MW

So, at the top of conservation, our 2 MW installed capacity will not be able to be met.

We can see from the figure below that once the pool elevation reaches 62.5 ft, the release increases to try to meet the generation target of 2 MW.  Note that I have a simple linear elevation-storage curve modeled for this reservoir to make the results easier to comprehend.  Prior to that, the release is decreasing with increasing pool elevation to meet the 1 MW total.  In other words, as the pool rises, the greater head differential allows for a decrease in release to achieve 1 MW of power generation.

The figure below shows the power results for this simulation.  The capability of the power is shown by the blue line.  The red line shows the required power generation.  Recall that this is 1 MW for power storage below 50% and 2 MW for power storage above 50%.  The green line is showing the actual power that is generated.

The power plant is able to meet the 1 MW requirement since the capability of the power plant exceeds this amount for the given parameters of flow, head differential, and efficiency.  However, once 2 MW is required, the power plant is unable to meet this requirement.  The power generation is set to the capability of the plant during this time to come as close as possible to meeting the requirement.