Generator and Electrical System - Small Wind Turbines: Analysis, Design, and Application - page 241

Table 11.2 Possible protection issues (response)
Wind turbine Generator Battery (if present) Inverter or load

Over-speeding (slow
down or stop)

Over-current (reduce
current or
disconnect)

Over-charging (stop
charging)

Short circuit
(disconnect)

Extreme winds (shut
down and stop)

Over-voltage (reduce
voltage or
disconnect)

Excessive voltage (stop
charging)

Over voltage
(disconnect)

Excessive vibration
(reduce turbine
speed or stop)

Too hot (reduce
current or
disconnect)

Too low voltage
(disconnect load)

Under voltage
(disconnect)

Excessive noise (reduce
turbine speed)

Smoke present
(disconnect)

Too hot (reduce charging
or load current as
appropriate)

Too hot
(disconnect)

Smoke present
(disconnect)

Smoke present
(disconnect and
turn off)

the battery can cause over-heating and damage whatever is drawing the current.
A lesser effect of the battery over-heating is that its lead plates may expand and
bend, thereby shorting. A battery short circuit has been observed on a wind-
charging system where it not only started a fire at the short circuit site, but
eventually melted the lead battery posts.
When protecting against over-currents, fuses and circuit breakers are commonly
used, although it is possible to use controlled power electronics switches or sac-
rificial components like metal oxide varisters, MOVs. Due to their simplicity and
relative reliability, fuses and circuit breakers are often used as the protection of last

Loads

3 phase
generator
output

Rectifier/
Controller

Dump load Battery Inverter

Shorting switch

Fig. 11.13 Small turbine system with basic circuit breaker and switch protection