If a power utility company is installing capacitor banks in its network, is it better to invest in high quality switch gear equipment so it is possible to switch capacitor banks more than once every day / every week / every month? Automatically or manually? Or in compensation with capacitor banks is more efficient to switch them manually twice a year on high and low load seasons? I guess it depends on the load profile of the network. Is it cost efficient to have manually adjustable high voltage capacitor banks or for adjustable compensation is better to use other methods like Volt VAR control, FACTS, etc? References are welcome.
Capacitor banks are the most cost efficient way to provide vars. Things like FACTS are much too costly for most situations.
So your goals will determine the switching frequency needed. If you only need to compensate for seasonal variations in the load (for example, increased air conditioning in the summer) switching a few times a year may be sufficient. On the other hand if you want to compensate for large daily load variations (for example a factory requiring a large amount of power for several hours during the day) you may want to switch several times a day and, as you have already pointed out, a high quality switch is probably needed.
There is also an increasing trend to use conservation voltage reduction, CVR, to reduce power consumption, especially during peak load periods. CVR works by reducing the voltage and consequently reducing power. It is most effective with constant impedance loads where power is proportional to the square of the voltage. To receive the maximum benefit of CVR the voltage profile along the line must not vary much. This leads to increased use of capacitor banks and switching thereof. So if CVR is in your future, you may want to consider high quality switches.
My former company, S&C Electric Co., provides quality equipment for the control of capacitor banks. Please reference www.sandc.com for more information.