Solar Grid Inverter Monitoring System - Part 2

The second part of this project requires the RS232 to be signalling at a longer distance than the usual fifteen metre limitations.

To overcome this distance limitation and maintain reliability of the serial network, we use of a special telecommunication device called a RS232 extender. 


The RS232 Extender

The Gefen RS232 extenders will be used to extend the RS232 connection from the Fronius IG grid inverters to the remote location, with over one hundred feet of Cat5e cable.

The Gefen RS232 extenders will perfectly reproduce all 9 pins from one end to the other and have the ability to provide power over Ethernet to the second extender, saving on extra cables and power supplies.

The extender units act as a sender and receiver pair on the RS232 network. Allowing the grid inverter's data logger to send Windows computer information to the Fronius access software.

The RS232 extender sender unit connects to Fronius IG grid inverter at one end and the RS232 extender receiver at the computer terminal at the other end.

Then the Cat5e cable connects the send and receive extender units, over 300 metres away. The sender unit is powered by a 5 volt power supply, which will also power the receiver via the Cat5e cable.


The Fronius IG Access Software

The free Fronius Solar access software is available for download from their corporate website at http://www.fronius.com. The software provides advanced onsite data analysis and archiving options for the PC. As an administrative tool, it offers full setup options for all system components in Solar Net.

The software is easy to install on the Windows system, with a helpful installer wizard.

Once installed, the software is located in the programs section of the windows start menu.

The Fronius access software splash screen displays the general energy output information for the photovoltaic solar power system.

Under the administration menu, the new PV system can be added and configured for the RS232 connection back to the grid inverter's data logger.

In the next part of this series, I will be looking at connecting the monitoring software and data logger to collect information from the school's solar power system, and explaining the features and advantages that computerised power monitoring can have for an organisation.


Other PV Solar Powered Systems and Concepts

A PV solar power system has many other applications apart from grid power installations. One example is NASA's Helios aircraft, remotely piloted to fly at high altitudes.

The electrically powered Helios is constructed mostly of composite materials such as carbon fibre, graphite epoxy, Kevlar, styrofoam, and a thin, transparent plastic skin.

The main tubular wing spar is made of carbon fibre. The spar, which is thicker on the top and bottom to absorb the constant bending motions that occur during flight, is also wrapped with Nomex and Kevlar for additional strength.

The wing ribs are made of epoxy and carbon fibre. Shaped styrofoam is used for the wing's leading edge and a durable clear plastic film covers the entire wing.

The Helios collects a variety of information in the atmosphere, and runs mainly on solar power.

On August 14, 2001, the Helios Prototype, piloted remotely by Greg Kendall, reached an altitude of 96,863 feet, a world record for sustained horizontal flight by a winged aircraft.

The altitude was more than 11,000 feet or more than 2 miles (3.2 km) above the previous record for sustained flight by a winged aircraft. In addition, the aircraft spent more than 40 minutes above 96,000 feet.

Tragically the Helios crashed over the Pacific Ocean on 26 June 2003.

Solar Activity and the Risks to Modern Technology

In the middle of our solar system sits a incredibly large nuclear reaction held together by an enormous gravity pull. Many millions of times the mass of the earth, this star emits solar weather that stretches out past the orbit of Pluto. As with weather on earth, the sun's weather can form destructive storms that stretch out from the sun's surface onto the Earth and further into the solar system.

These solar storms are full of particles (protons, electrons, and plasma), radio waves, x-rays and other forms of energy that come from nuclear reactions.

When these storms reach Earth, they can having varying effects on our planet.


What does this have to do with Technology?

Most technology systems, with the exception of the military and some corporate technology, have no built-in resistance to the effects of extreme solar storms.

This means that most of our electronic devices, electric motors and power systems are very vulnerable to solar activity, which may render the devices partially or totally inoperable.


Why Should we be Worried About the Effect on Everyday Technology?

On September 1–2, 1859, the largest recorded geomagnetic storm occurred. Aurorae were seen around the world, most notably over the Caribbean; also noteworthy were those over the Rocky Mountains that were so bright, the glow awoke gold miners, who began preparing breakfast because they thought it was morning. Telegraph systems all over Europe and North America failed.Telegraph pylons threw sparks and telegraph paper spontaneously caught fire.

Some telegraph systems appeared to continue to send and receive messages despite having been disconnected from their power supplies.

This storm was called the Carrington Event and similar strength storms reach the earth every few hundred years.

A storm like the Carrington Event today would cause most of our modern technology to fail within hours. There would be significant electronic damage, power failures, global financial confusion, and disruption to transport and communications.

Without active help and intervention, areas of the earth could experience famines, civil unrest, and wars.



Recent Solar Storms and Increasing Activity Causing Increased Risk

On the 3-5th of August, we had a geomagnetic storm interact with the Earth, causing a G3 storm event to our magnetosphere.

This storm was impressive, but lucky not a threat to most communication and power systems. However, it posed large issues for satellite operators and space operations.



G3 Solar Storm Effects:

Power systems:  voltage corrections may be required, false alarms triggered on some protection devices. Spacecraft operations: surface charging may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems. Other systems: intermittent satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent, and aurora has been seen as low as Illinois and Oregon.

All the definition for the scales of geomagnetic storms, solar radiation storms, and radio blackouts levels are located at the NOAA (National Oceanic and Atmospheric Administration) website. http://www.swpc.noaa.gov/NOAAscales/index.html

NOAA also has a website devoted to monitoring solar storm activity and contains other excellent information on solar activity. http://www.swpc.noaa.gov/

This current solar cycle is showing signs of the beginning of a very active period for solar storms and risks to the earth.

This cycle will continue to increase in activity for several years before subsiding into a calmer part of the cycle.


What to do About the Risks of a Solar Storm?

The issue needs to be treated like an natural event, similar to earthquake risks. As with earthquakes on Earth, we have built better buildings, invest in detection and prediction, educating people and designing government polices to deal with such a disaster.

Just with earthquake risk management, solar storms need to be addressed to minimise the harm to our way of life.

Possible improvements to solar flare storm risks:

• More EM shielding in electronics devices
• Better designed power systems and grids.
• Better warning and forecast of solar storms
• Understand the sun and it's dynamics better.
• Education of people on the topic in a meaningful way.
• Government polices on the issue, risks and reactions to events.

Through education of the public, better understanding of the sun and laws requiring built-in protection for important devices and systems, the world can become resistant to this type of event.

We may never be able to remove the risk of solar storms, but we can minimise its harm to our technology driven world.

Easy ESXi 4.1 with serial or USB UPS control

In the past, there has always been a problem with setting up USB uninterruptible power supply to VMware ESXi servers.  Here is the method of enabling a VMware ESXi 4.1 bare-metal server to communicate with an inexpensive serial or USB-only UPS system.

Install a Guest Windows System

You will need to install a Windows virtual machine to run the power management software, and connect to the UPS system.


I have used APC Powerchute software on a Windows 2008 server with this installation method, and encountered no problems.

Most Windows OS guests with USB management software should work in the same way.


Enabling the USB Pass-through  

Now that ESXi 4.1 has been released, it is possible to use a USB data cable on any UPS and communicate with Windows control software.  

ESXi 4.1 has the ability to make a USB connection from the server hardware, directly through to a virtual machine hosted on the same server.

This allows UPS monitoring software to run on a windows virtual machine on the server and talk to the UPS on the ESXi server USB hardware.

You will need to make sure the USB adapter is attached to only the power controller guest OS, to minimise other guest OS conflicts. 

The management and attachment of the USB hardware is done in the virtual machine hardware configuration screen.

When adding USB hardware to the hardware of the virtual machine, a new option is now available for direct USB hardware access.


Enabling the SSH Service for Root Access

The next step is to enable the SSH service on the ESXi server, so a root remote console is present via SSH.

You will need physical access to the ESXi server, so you can login to its console as the root user.

Edit the configuration file for SSH with the following command:

nano /etc/ssh/sshd_config

Find the line that starts with PermitRootLogin and change the "no" to "yes".
 
Restart the sshd service with the command:

service sshd restart

The SSH service will now accept root logins to the console for running scripts. 



Windows Guest Script File  

On the Windows virtual machine running the Powerchute software, a small .bat file needs to be created, pointing to a free SSH client called Putty.

You can download Putty from their website. http://www.chiark.greenend.org.uk/~sgtatham/putty/ 

After getting Putty and setting up the .bat script, log into the same directory on the Windows guest. 

You will be able to point your UPS control software directly to the shut-down script on the local host.

Windows .bat file:
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putty "server-address" -l root -pw "password" -m Unix_Commands

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Unix_Commands file:
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poweroff

exit

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Final Notes

This new feature for USB connections in ESXi 4.1 makes it very easy to implement UPS systems into the VMware environment. I have only tried this with Windows 2008, running APC Powerchute software and uninterruptible power supply with USB control. But I believe any configuration of Windows and power control software should work.