The power company is partially to blame but fat chance they'll help out. If you are at the end of a rural line, there is a good chance that your problem of voltage sag is caused by power line faults from things like tree branches, damaged power poles, animals, birds, rain, snow, etc. These faults reduce the grid voltage downstream of the fault - and since you are the most downstream user, you see the fluctuations. These can be corrected by power company maintenance but rarely do they have the manpower to cover the large real estate on a daily basis.
One way of solving the voltage sag is to install an electronic sag protector or dip proofing inverter. These are, in essence, power supply capacitors with an ac inverter. Too expensive to do it for the whole house. Instead, install a subpanel from the main service panel and install the inverter in the subpanel. The size of the inverter should be 2 kVA per circuit. Keep it simple - a subpanel with 3 dedicated circuits and a 6 kVA single-phase inverter should solve your problem. The other way of solving this is to install a generator (too costly and noisy).
Another problem you may face is the 100 ft of buried service conductor. It may be too small. If your service is 100 amps, the size of the conductor should be 1/0 (three sizes larger to accomodate the voltage drop and the derating from burial). Have an electrician confirm, and, while he's at it, check the grounding to see if it's less than 25 ohms. He should also check to see that all phase conductors in the panel are tight. Best of luck...
One way of solving the voltage sag is to install an electronic sag protector or dip proofing inverter. These are, in essence, power supply capacitors with an ac inverter. Too expensive to do it for the whole house. Instead, install a subpanel from the main service panel and install the inverter in the subpanel. The size of the inverter should be 2 kVA per circuit. Keep it simple - a subpanel with 3 dedicated circuits and a 6 kVA single-phase inverter should solve your problem. The other way of solving this is to install a generator (too costly and noisy).
Another problem you may face is the 100 ft of buried service conductor. It may be too small. If your service is 100 amps, the size of the conductor should be 1/0 (three sizes larger to accomodate the voltage drop and the derating from burial). Have an electrician confirm, and, while he's at it, check the grounding to see if it's less than 25 ohms. He should also check to see that all phase conductors in the panel are tight. Best of luck...