Dynamic and Static IP Addresses

[#1]

I have a dynamic email address.  I had assumed that provided you do not switch off your router, you would normally remain stay on that address.  In the last few days, I found that my address has changed, even though I have not switched off my router. 
I ask the question because I look after a website (hosted by Madasafish).  I have installed Google Analytics to the site and do not want my own visits to be recorded, i.e. to distort traffic figures.  I entered my IP address as a filter on Google Analytics, therefore my visits to be ignored.  However, in the last  couple of days I realised that Google Analytics was starting to record my visits.  A little more investigation revealed that my IP address had changed.
My Router log shows a disconnection and then a reconnection on 30 November around 09:30.  Possibly that is reason for the changed address?
I assume this is disconnection entry from the log:  Nov 30 09:23:05 pppd[391]: LCP terminated by peer
I wonder if this is disconnection in the ISP network or something at my end?
Do PlusNet change an IP address even where the router is not disconnected? 
And how often do disconnections occur?
Any comments on these points would be appreciated.
Finally, I hope I have posted this topic in the right forum?
Thanks

[#2]

The IP Address can and probably will change when there is a drop of PPP session and it is likely that the outage yesterday may well have done that even if the router did not lose sync
If you want to keep the filter working why not pay the one off £5 charge for a fixed IP
Re the right forum - probably not but as I have answered it there is no immediate reason to change it

[#3]

The disconnection was quite possibly the result of the network outage yesterday morning.
Log into your account, click on the Internet tab and activate a static IP for your account. That will stop it changing.
Edit:

Quote from: Oldjim

If you want to keep the filter working why not pay the one off £5 charge for a fixed IP

If the OP has a Madasafish broadband account then there is no charge for a static IP.

[#4]

Thanks for replies.  No, don't have a Madasafish Broadband account, although domain and website are hosted by them.  My Broadband / Fibre is PlusNet, so I do all uploads to the site via PlusNet.
I don't suppose there are any technical disadvantages to a static IP?

[#5]

Quote from: grecian

I don't suppose there are any technical disadvantages to a static IP?

Not in my opinion. Plenty of sites if you search for them detailing the advantages/disadvantages. Some might say it's less secure because you're always reachable at the same IP, I'm not one of the people in this camp though

[#6]

Yes, as suggested I have found a number of sites that give the pros and cons. Very useful.
I will decide when I am 100% sure that Google Analytics is ignoring my visits to the site!

Many thanks.