The "Perfect Storm"

In April the southeast U.S. was hit by a line of severe thunderstorms that National Geographic has called an "unusual 'perfect storm'." Warm moist air off the Gulf of Mexico collided with arctic air carried south by the jet stream causing one of the worst outbreaks of thunderstorms in recent meteorological history. The storm front spawned over one hundred tornadoes and killed 283 people throughout six southeastern states.

  
Tuscaloosa Alabama was hit particularly hard by a massive EF-5 tornado which cut a swath over a mile wide and stayed on the ground for an unprecedented 300 miles across Alabama and Georgia. Storms such as these wreak havoc on all utilities. Repairing the damage after such devastating events, often while dealing simultaneously with personal challenges, can be a daunting task.

Tuscaloosa Residents Survey Tornado Damage

The city of Tuscaloosa has been a Mission client since 2005 and has deployed a "hybrid" radio/cellular SCADA sytem for their water and wastewater operations.  They have about 30 RTUs on a 900 MHz MDS radio system, about the same number of Mission RTUs, and 4 RTUs using DSL leased lines.  All units interface with their proprietary HMI software using the OPC protocol.  

According to Keith Elmore, one of the electronics technicians tasked with maintaining the Tuscaloosa SCADA system, the Mission units performed extraordinarily well during the crisis.  Even though the storm knocked out data feeds to their SCADA servers at the office, Keith and his team of co-workers were able to monitor their lift stations from alternate locations using the Mission website. According to Elmore, "We monitored the stations from our home computers and were able to dispatch crews to the most critical areas. We got through the crisis without any really serious problems." 

Most of the cellular service to the Tuscaloosa Mission RTUs was not affected by the tornado and only a few units briefly lost communications. Elmore credits the cellular providers with acting quickly to get portable towers to cover the affected areas, allowing them to continue monitoring those stations with very little interruption. The utility pressured their local provider to have the DSL service to their internal HMI up and running five days after the tornado struck, allowing Tuscaloosa to return to "business as usual" within the sewer and water department. 

Reporting Flow Data

Mission supports two methods of reporting flow. The first is a "pulsing" meter output into our option board (one pulse per 10 gallons, for example). The other is to integrate an analog input (convert GPM to gallons by multiplying gallons per minute times minutes) into a Mission M-800.

While cellular communications failures are rare, they do happen. If the analog flow reporting method is selected, communications failures will impact the accuracy of the reported data. If service is inturrupted for any reason, our pulse option board contains a counter separate from the main RTU which operates even when the RTU is not online (even when it is powered down), and therefore the correct pulse count will be reported when communications with the main servers are restored. If the operator wants to alarm on particular data, or needs to collect and report that data, we recommend that the pulse type flow meter be used instead of the analog integration type.

Save Money on Your Power Bill

Electric utilities use two primary types of plants for power generation - "Base Load" plants which do not change their production, combined with "Peaking" plants which can rapidly adjust to meet changing demand. Base load plants tend to use relatively inexpensive fuel (coal, for example) and the utility needs to have enough peaking plants in order to handle the maximum power demanded by their customers. Increasingly utilities are using a carrot (or stick, depending on how you look at it) called "Time Of Use" (TOU) pricing to try and coax consumption from the peak times to the off-peak times. They do this so that they can get the most efficient generation, and so they don't have to build additional peaking plants for times of highest demand. As an example of the potential savings, Portland General Electric in Oregon sells power at 13.3 cents per kWh during peak hours, but charges only 4.4 cents per kWh during off-peak hours.*

The vast majority of large fresh water tank filling operations have fairly simple control logic that says, "If the level is below here, turn the pump on, and if the level is above here, turn the pump off." In systems like this the fill cycle can start whenever the tank is low, which can be at any time of the day or night. What if a utility could take advantage of the off-peak power rates to fill its water tanks?

Using the new force-fill feature with the Tank-and-Well application, Mission customers can specify at what time the tank is to be filled. This new logic computes an average fill rate for each tank and will turn the pumps on at a time that will cause them to be topped off just before the power price increases. For example, in a tank that is four feet below the filled level, and fills at 1 foot per hour, the pumps will be turned on at 2AM in order to fill the tank by 6AM when the price increases. Each night the tank level and fill rates are dynamically calculated to ensure that the maximum water is stored in the tank using the least expensive power. In addition, "emergency" pump-turn-on levels (tank levels below which the customer doesn't care that the power is more expensive) are also included.

If your electric utility offers TOU pricing, talk to Mission to see if your operations can take advantage of the nighttime "sale" on power rates.