Back to work again…

After a month off it's been a bit tough to get back in the swing of things. I finished most of the turbine testing before going to Nepal, so now I'm moving on to the electrical side of the project. We have decided to have a power electronic interface between the generator and the grid, so the first part is looking at how to connect inverters in parallel without any central control or stiff grid (like our National Grid). I'm finding this really quite hard, and have started at the basic electrical theory to understand what's going on. There several examples of these control systems in literature - for example here - and I'm using these to start some simulations of inverters connected together in Simulink.

Synchronising parallel connected inverters (the lines are the frequency of two different inverters)

I'm going to be using single phase inverters, as then we won't have to worry about balancing the loads across each phase, as with a three phase system. However, this leads to some problems. With three phase, there are some mathematical transforms that change the 3 sinusoidal voltages into vector quantities, which are much easier to control. With single phase, sadly there is no equivalent. However, there are some ways to get around these problems, so I've been investigating the different solutions to see which will work best.

Buckingham Palace coach

Apart from work, I've been busy and not had a weekend free really. At the end of August, Hannah and I went to see the Queen. Well, we actually we had a look around Buckingham Palace State Rooms. It was amazing, so much gold I have never seen in my life. After the wedding of the year, they had an exhibition in the Palace about the Duchess of Cambridge's dress, and displayed it. I couldn't believe how small she was, I doubt the dress would have been much wider than my thigh… There was also an amazing display of Faberge Eggs and other trinkets. I'm not normally one for jewellery or the like, but they were so intricate, it was just incredible.

Back of Buckingham Palace

We also visited the Royal Mews, where the state carriages and cars are kept. To think of the people that these cars and carriages had carried over the years was just mind-bending. For bank holiday weekend, we went to see my Mum and Dad's new bungalow that there are refurbishing. As it was a really hot and sunny weekend, my Dad had the perfect job for me - remove the insulation from the loft so the electricians could come in and look at the wiring. This was a joyous job, sweating through every pore in a suit that made me look like an Oompa Loompa from Willy Wonka and the Chocolate Factory. At the end of the day, Dad and I managed to clear all insulation - my nose wasn't the same for a few days after though - which was great, and he's now put it back in again with a load on new thicker insulation on top of it. It's going to be one toasty house - energy-saving-tastic! 

Me in the Oompa Loompa suit

The first weekend in September was the Small is… Festival run by EWB-UK and Practical Action. The name of the festival comes from the title of a book written by Practical Action's founder, E.F. Schumacher, Small is Beautiful. It was an interesting festival, looking at different solutions to problems - energy, sanitation, cooking - through a mix of workshops, discussions, panel sessions and practical activities. Some photos from some of the sessions I attended are below (taken from the Small is… festival website).

Playing with a Solar Panel at Small is… (Photo by Nick Holmes)

Watching the charcoal burn

Listening to V3 Power talk about homemade wind turbines (Photo by Nick Holmes)

I found it quite interesting listening to a wind power debate between a manufacturer, Ampair, NGOs, social enterprises and academics. It got quite heated at some points, but I think some interesting arguments on the advantages and disadvantages of locally made equipment compared with mass manufactured certified designs came out above some of the animosity. As the man from Ampair said, they would set up a turbine factory in a developing country, like Peru, if they could be sure that an NGO wouldn't come in with free money and completely undercut them with inferior hand made products. I'm not sure who I agree with, but an interesting discussion none the less. Hannah came along with me, and I think it was quite a shock for both of us to hear some of the statistics to do with smoke inhalation from open fires, and the health problems that it causes.

Every year in September, Bristol opens all the public buildings for a day - even those normally closed. Hannah and I went on a train along the floating harbour down to the SS Great Britain, then onto the Create Centre where they have an Eco-house and a hazard awareness area for children, which we took  a tour around.

The train outside the M-Shed for Bristol Doors Open Day

Then we visited St Stephen's Church, where we booked ourselves on a jaunt up the tower. The tower looks out over the centre of Bristol, and I thought it would be quite fun to climb. The stairs were very awkward, all stone and not very large to fit my size 13 feet on, with the twisty turns. By the time I got to the top, I have to say I was quite relieved. However, my severe fear of heights kicked in and I didn't really manage to see the view!

St Stephen's Church Tower (we climbed up it, all 152 ft!)

Bell ringing in St Stephen's Church

On the way down, even more scary than on the way up as every step we felt we would slip down, we stopped off at the bell ringing level, and I had a go. I've never rung a bell before, and it was really difficult to try and get it in time.

SAM