“Solar & Wind Strategies, Projects and Technology Developments was the Hot Topic Hour September 12, 2013

 

Can PMU Technology Contribute to Improved PV Plant Monitoring and Control?

 

This was just one of the questions addressed by Juris Kalejs of American Capital Energy (ACE). Kalejs discussed work in progress on the development of a Synchrophasor (PMU). This project is a joint effort of Georgia Institute of Technology, Sandia National Laboratories and American Capital Energy.

 

Kalejs began by explaining that the current system of SCADA-based PV power plant supervision will be inadequate when the concentration of solar energy feed to the grid reaches 20 to 25 percent. A combination of Smart Grid for demand-side and enhanced real time PV plant generation-side monitoring and control may be the solution.

 

A PMU-based PV Plant Real Time Operation and Control System would collect data 60 times per second. GPS synchronized data acquisition systems are preferred. Both AC and DC sides are monitored. The data are collected at a PC which time aligns the data and performs state estimation that provides the validated real time model for utility ancillary services.

 

The alpha test site is an ACE 1,160 kW PV plant for the Buckman water treatment site in Santa Fe, NM. PMU data is useful for model validation. Typical SCADA data, even a one second resolution does not have sufficient detail. Control function implementation will require the next generation of “smart” inverters in addition to software upgrades to real time monitoring.

 

Case made for Hybrid Solar/Fossil Plants

 

Peter Johnston of Burns & McDonnell Engineering discussed Strategies, Projects and Developments for Solar Technologies. Johnston began with a review of PV solar and solar thermal technologies. He explained photovoltaic is the direct conversion of light to electricity while solar thermal is the collection and use of the heat energy from the sun usually to boil water to make steam and power a turbine/generator.

 

The majority of all solar power systems installed in the last five years were PV. At $2.40/Wac it is currently at its lowest cost ever. The advantages of PV solar are cost, modularity and ease of installation. The disadvantage is its lack of storage capability.

 

Solar thermal plants have a potential for energy storage and the potential to integrate with fossil plants. On the negative side they cost almost twice as much as PV plants and require almost twice as much land.  They need direct solar insolation and water for mirror cleaning and power block cooling.

 

Johnston made a case for hybrid plants. A solar thermal plant could provide supplemental heat to an existing fossil-fired power plant offsetting fossil fuel consumption. This could be relatively cheap solar MWh since the power block has already been capitalized. He suggested designing for new plants rather than retrofitting old.

 

Solar doesn’t have to generate electricity, reminded Johnston. It can be used to replace electricity. Air conditioning systems are the largest customer and utility load in the southwest. In this application solar energy can be used to run the absorption chillers.

 

Several policy changes were suggested. Reducing the permitting phase from years to months was one.  An example was Gila Bend, AZ where the town council zoned an area for solar development. This reduced the permitting time to four months.

 

On the subject of DOE loan guarantees Johnston indicated these should go to project developers not manufacturers. More independent oversight is also needed.

 

Last but not least, more transparency is needed in the industry – What’s working – what isn’t.

 

  

Bios, Abstracts and Photos can be seen at BIOS, ABSTRACTS, PHOTOS 9-12-13.htm

 

The individual presentations are as follows: