Hi all,

I have been asked to look into the technical and practical aspects of connecting PV plants to the Kenyan grid, to operate in grid-support mode - so parallel operation with automatic islanding during loss-of-mains (ie load-shedding). Generator capacity is TBC as we have yet to run the analysis, before anyone asks.

One particular project I am looking at is on a plantation, so I suspect that there is a chance I will be some way from the main Kengen grid but near a local network.

I am used to the way the UK works, but this is a new venture so I haven't yet found my feet in terms of grid structure, processes, standards etc.

Does anyone have any experience with electrical work in Kenya? Or islanded projects in similar locations? Any advice welcome.

Thanks,

James

PS - I have seen one post on Kenya from five years ago, but there wasn't any update post-completion...

I have experience in the design of power supply systems for islands, though not of Kenya specifically.

I think a useful starter would be to check out the features of the Sunny Island range of inverters from SMA.

Your biggest issue with operation in island mode will most probably be in achieving safe and effective clearance of faults with the very low fault levels from inverters and small/ medium sized diesel generators.

Happy to help further when you're a bit further on with your overall design requirements. Feel free to use PM.

Jonno

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Jonno

Thanks for that - I was wondering about fault levels too.

It's interesting that you've got experience with the Sunny Island design - we were already thinking about going that way. Given the nature of the customer's loads we're quite likely to exceed the 300kVA nominal limit of their Cluster cabinet concept (possibly by some way), but I met with one of SMA's engineers at Intersolar and he seemed okay with the idea of exceeding the limit on the proviso that we'd have to build the distribution.

We had a briefing with the Client earlier this week and have a bit more information, but I've sent them away with some homework so that we can start to get a realistic handle on the specification. As always, economics will play a part in the design! Interestingly though they did say that part of the project would be to provide small power to their staff houses, most of which are currently on kerosene lamps. Do you have a handle on consumption before and after installation of a reliable power supply? Tthe Client mentioned that a major load was the mobile phone charger, but I'm guessing lighting will play a part.

Finally, these sites will be hybrid, with two diesel generators (different sizes), PV and (sometimes) the grid; We normally do our modelling in PVSYST (or PV*Sol, for domestic / small commercial projects) but I'm not sure that PVSYST will properly emulate the Sunny Island interaction with three independent "on-demand" energy sources. I see SMA have their own software - have you used it and do you rate it ... or would you recommend something else? Otherwise I might have to take the PVSYST hourly output and create a spreadsheet to set up various diesel / grid availability scenarios.

Cheers,

James

I think you need to tap into local culture, aspirations etc. I know if I lived there, a high priority would be refrigeration! Lighting and radio is likely to be high on many people's lists. Other possible scenarios could include individuals setting up businesses in recharging batteries for others for mobile phone, lighting and radio.

Two key parameters for system design are maximum demand and total energy consumption. How will tariff charges (a powerful driver)reflect these? I recall that we included means of limiting maximum demand (these can be self reset or be arranged to require the system operator to attend to reset (at a charge)). We also used "PowaPlugs" (google it) to provide demand side management control. These operated in 2 modes - 1 to reduce maximum demands at times of peak demand to protect essential loads and provide system stability; and 2, to add secondary loads when there's a power surplus so that the output from renewables can be better utilised. These work quite effectively with networks where frequency changes reflect the balance between generation and demand (and the Sunny Island inverters are compatible with these). Suggest you get in touch with Senergy Econnect on these clever little devices which have been used on many remote power systems.

I'm aware there are sizing packages around but I've left the driving of these to others having found the back of a fag packet suited my purposes (and that of checking the outputs of the sophisticated packages). XL works OK for non-smokers, but has inappropriate accuracy!

Jonno

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Jonno

If you are talking about electrification at places like Marsabit and Mandera; these both had 100 odd to 50 kW diesel sets and a few kilometres of 11kV and sagging LV lines several decades ago. There is plenty of sunshine but little water in northern Kenya. Transport is over terrible dirt roads and the fuel tankers to Mandera could take a week to get there; if they did not brake down on the 400km road
Main loads were water pumps and fridges with a few lights, fans and radios in evenings, if I remember correctly.
Cooking was on charcoal/wood or bottle-gas.
CliveS