Three years gone, Six months to go… (almost anyway)

I remember being told by my Mum that the road to hell is paved with good intentions. And all my good intentions at the time last year to blog bi-weekly definitely have made my path to the hot place a little bit more easy. So, in penance and to try blogging again here we go.

A lot has happened since September last year, and I'm not quite sure how best to do this, so I've decided to give a bit of photo diary of the last 12 months to give a taste of what's been going on both in PhD-world and my own.

In October/November I was working on the stability analysis of parallel inverters, using small signal stability analysis, the results of the analysis match the simulations relatively well, hopefully these will also match the experimental work as well. Below is the pole-zero plot for the parallel inverters.

Pole-zero plot for parallel inverters

I met one of the founders of Learning Planet, Justin Wickham, in London to discuss the pico hydro scheme they are looking at. You can see more of the area Learning Planet are in here or have a look on their website www.learningplanet.org.uk.

 

The School in Dhawa renovated by Learning Planet

My cousin Helen got married at the end of October, so we headed over to Ireland to celebrate.

Helen and me at her wedding

I helped on the sound desk again with Horfield Theatre Company for their October pantomime, Franky Panky and had a lot of fun - with innuendo and a lot of childish humour. I'm getting a little bit better on the sound, although every so often the wrong person's mic would be turned up… A fun fun week nonetheless!

Franky Panky's Poster

I had a "cruise" to Bruges with my little sister, which was fun - especially all the chocolate!

Me and a bear in Bruges

During November and December I wrote a paper on the experimental turbine work I'd been doing, and submitted it to the Journal of Applied Energy at the beginning of January. It was finally accepted in June, and published here in July! The paper that I presented at WREC was also published in Renewable Energy Journal in July this year as well, here.

A figure from the Applied Energy journal, the slug of water that's ingested by the turbine in one rotation

In the last weekend of November, Hannah and I went to Salisbury to celebrate two years. We had a fun couple of days and saw Stonehenge, the Cathedral, Avebury and the Uffington White Horse.

The Stone Circle at Avebury

I spent Christmas with my parents and sisters, which was great.

With my family at Mount Edgecombe

Back in the lab, I started working on an improved control system to try and reduce any current spikes when the two inverters connected together so that switches won't go bang when the inverters are connected to a grid. This improved control did what it was supposed to in the simulation.

Reduced current spikes on paralleling inverters

I had another family wedding in Ireland, my cousin Gillian got married in early February and Hannah and I headed over for the weekend. Unfortunately snow made our journey back delayed… (I blame Gillian's sister, Jenny, who flew back with us!)

Gillian and Alex's wedding

I found an IEEE conference in Kathmandu that would take place in late September, known as ICSET. I wrote two papers for this conference, one on the turbine testing and the other on a simulation of a off-grid pico hydro network, submitting them by the end of March, which were approved. I'm off to Nepal on the 17th September, which is going to be amazing.

A simple model of an off-grid pico hydro network

I also attended and presented at the EWB research conference at UCL at the end of March, adding to the stress at the time, but really enjoyed it and was interested to hear some of the other projects going on in the EWB universe.

AC grid with distributed generators connected with inverter front ends

After submitting the papers, Hannah and I went off to India for two weeks, and had the most fantastic time. We spent a week in Kerala and a week in Bangalore, and had some amazing experiences, spending a night on a houseboat, riding on an elephant, and visiting some beautiful parts of the countryside.

On a houseboat in Alleppey, Kerala

On returning from India, I started to build some electronics, starting with a simple inverter, four switches and an inductor-capacitor filter. I built a simple control circuit in analogue components to control the output current to a reference sine wave from a signal generator. The circuit managed to produce a relatively good output.

Inverter Mk1 and Output

At the end of April, Hannah and I went to see one of my favourite bands, Feeder, in Cardiff. They were absolutely amazing. Enough said.

At the Feeder gig

By the beginning of May, it was time to do 'Living Below the Line' again (see last years version here). We raised money for MRDF and this time, there were a good 10 of us that did it.

Pasta Dinner during Live Below The Line

Once the original inverter worked, I built a second checking it worked with the basic controller, and then used a real time controller called dSPACE which can use MATLAB models to control things, allowing quick changes to be made to the model and be able to see the result of it. Both inverters worked controlled by the dSPACE which was great.

Parallel Inverters with dSPACE

The Olympic Torch came to Bristol in May, and we went down to the Harbourside to see it. The city was buzzing, and we had a fantastic time watching it arrive.

Olympic Torch arriving in Bristol

I ran a quick tour of the Hydrolab for the University of Bristol's Open Day in June, and showed some of the potential new students around and demonstrated the turbine rig. By the end of the day, my voice was hoarse, but had talked to many hundreds of people.

Turbine rig running

Obviously with London holding the Olympics, I wasn't going to miss going to see some events. We went to see the Beach Volleyball on Horseguards Parade and some Hockey in the Olympic Park, just a most fantastic experience.

Beach Volleyball at Horseguards Parade

Once each of the inverters worked individually, I connected them together, to see how they would work in parallel. They synchronised without blowing up, which was always good, and now in my work I'm trying to improve the performance of the system.

Parallel inverters

Every year Bristol holds an International Balloon Fiesta in Ashton Court, on the outskirts of Bristol. We went to the Nightglow, where the balloons light up to music, and saw a mass take off with Tim, who had come over from New Zealand.

Balloons at the Nightglow

We had a few days in Cornwall, camping. It rained, well it was Cornwall after all, but had a few nice and sunny days, especially down on the Lizard and ate some rather tasty ice-cream too…

Lizard Lighthouse in the sunshine!

A couple of weeks later we returned to Cornwall for a school friend's wedding. Again it rained, and it didn't really let up this time. Argh. Still, we enjoyed an ice-cream in the rain.

Hannah eating an Ice-cream in the rain at Lanhydrock

As well as the Olympics, we also got some tickets for the Paralympics, this time for the swimming, athletics and also saw some judo and table tennis. If anything, we enjoyed this more than the Olympics, the atmosphere was just incredible.

The long jump in the Olympic Stadium

And straight from the Paralympics we headed to the Small is Festival 2012. I had been asked to do a little workshop on pico hydro, and so designed a workshop to build a little crossflow turbine and test it, the workshop went really well and I had a very inspirational weekend. And it didn't rain!

The workshop at Small is Festival

So, hopefully now you're all about caught up with me and my life. I'm really sorry it's taken so long to do this, but I hope I'll be a bit more regular. Not long to go with the PhD now either. Times are scary and fun!

SAM

Sweden Bound

So, WREC starts tomorrow, so I've been preparing my presentation over the last week. As I've been doing the living below the line challenge I've not been the most happy and smiley person this week, the lack of food has made me slightly more grumpy than normal (many would say this is a great feat as I'm fairly grumpy most of the time anyway!) and so the pressure to get a good and coherent presentation together hasn't helped the situation. However, after a couple of iterations during the week and a practise on Friday I'm quite happy with what I have. I'm going to be giving my presentation in the first hydropower session of the conference on Thursday morning, which means I'll have most of the week to see how everyone else does theirs and see what the style and level of the presentations are. I've also been thinking about the awkward questions that I'm likely to be asked so that I can have useful responses to them. The questions I think most likely are:

- Why don't people normally use these turbines at low head as they're not new technology?

- How big will the turbine be?

- What is the advantage of this compared with the axial flow turbine (the normal turbine used at low head pico ranges)?

- What about using pumps as turbines?

I've also learnt a bit more about what you need to do in a conference to present your work. You don't necessarily need to give all the data that's in the paper, in fact you can give more data than the paper and any new information that you've learnt. I thought I'd be able to only present what I'd initially written and so focussed my presentation on that, however I've been told that people aren't that interested in that, more what you're doing now and what you're going to be doing. Let's see how it goes…

As well as preparing for the conference I've been doing some further testing on the turbine. I've a new nozzle - 20mm diameter jet, which produced a fantastic 85% efficiency on the turbine. I have to say I breathed a sigh of relief. I was beginning to get concerned that my turbine choice I had made was fundamentally wrong. So the good efficiency measure is great news. Now we have to go forward with a organised testing regime, covering all the possible variables in the design - jet velocity (head, flow rate), jet inclination angle, jet impact location and so on - and see what affects the efficiency most, finding the optimum location. I'm still struggling with matching my model to the results - when I reached 85% the model was fairly close, within a reasonable error, but when the turbine moves away from this optimum point then this consistency with the model drops away dramatically.

So, to combat some of the problems with the model, I've been looking at further improvements, trying to implement some sort of 3D flow in the cup, as I've seen in the experiments that it is certainly not two dimensional flow. To see this yourself, if you put a spoon under a tap, as pictured below, you can see that the flow goes in all directions. This also happens in the turbine. However, form initial runs of this model, it doesn't seem to solve the problem, so I think I may have to come up with a completely new strategy. More frustration definitely!

Spoon and turgo cup under a 'jet' from a tap - see how the flow goes pretty much everywhere!

I've also been looking at some of the electrical building blocks I'll need to use in my system. Firstly the phase locked loop controller, that is used to synchronise two AC signals together. Once this was done, then I used it to control two independent voltage sources to parallel them up - replicating two generators connected together. I've managed to synchronise two units together - as you can see on the graph below:

Trying to synchronise two AC generators

Two problems have appeared though. The time to synchronise is quite long, about half a second, which is not really acceptable. There is also a 100Hz ripple in the frequency, as you can see the line is not at a constant frequency. This would not cause a big problem, but is annoying. I've tried filtering this out, but this causes a slow reaction in the control of the sources. So, these are a couple of problems to overcome.

I've bought my tickets to return to Nepal in July, which I'm really looking forward to. It's been almost a year since I was there last, and I can't wait to see all my friends again and just relax back into the wonderful culture and lifestyle that the Nepali's have. I met up with Tim Mitchell, a member of the Rotary club (Rotary Club) who does a lot of work with the Pahar Trust. The Pahar Trust are an NGO that build schools and medical posts in rural Nepal. They are also interested in electrifying them, and so after the IMechE presentation in March he came to talk to me about using the technology we're looking at to provide power to their schools. This is quite exciting as it could provide the possibility of test sites at the end of the project. So, I'm going to try and meet up with the Project Manager of the Pahar Trust when I'm out in Nepal, and maybe visit some of their projects.

I went home for Easter, as it had been a long time since I had been back to Cornwall. It was great to see my parents again, and Mary came down from up north for a few days, so all the family were together, quite a rare occasion. Hannah and I also decided to take a few days off on May Day bank holiday weekend, as we weren't that keen on watching THE wedding. So we booked a cottage just outside Abergavenny and plotted a weekend of walking, cycling (my choices) and shopping (Hannah's choice). We went to Brecon and found the Nepali shop there - I wanted to buy something, so bought some chiura and muri. Not very exciting, but still necessary. We went walking around the black mountains and climbed Sugar Loaf, which was blowing a gale on the top.

Climbing up sugar loaf

Near our house was Llanthony Priory which was destroyed in the dissolution of the monasteries in the mid 16th century. It was a very beautiful place to sit and relax, and quite interesting as I'd been reading some books about the dissolution period of British History.

Llanthony Priory

We cycled up the valley we were staying in up to the pass. Doing this we climbed over 300m, which almost killed both of us - I think I definitely need to improve on my fitness. But we had a really good picnic at the top of the pass, and then freewheeled most of the way back down the valley in 45 minutes, when it took us almost 3 hours to cycle up it!

The road to the pass - very very very tiring to reach it, so much quicker to go back down!

On the final day we went for a cycle on the Brecon Monmouth canal, much easier to cycle along and a nice relaxing time. We didn't want to expend too much energy though as we were starting to live below the line at that point, so we wouldn't be able to replace any lost calories with excesses of chocolate, as normal.

So, now I'm just about to head off to Sweden for my first conference. I'm nervous as anything, but looking forward to it too. Sort of!

SAM