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Protection & Control
Under-frequency load shedding function
It serves in case of frequency decrease due to lack of active power in a power system. This relay will automatically shed some loads according to the frequency decrease value, so that the generation and loads regain equilibrium. The under-frequency load shedding function provides 8 stages, which include 5 basic stages and 3 special stages.
Accelerated under-frequency load shedding function
In the case of serious lack of generation, this relay will accelerate load shedding according to df/dt, so that stage 2 and/or 3 can be accelerated to operate after stage 1 to promptly stop frequency decrease as soon as possible.
Over-frequency protection function
In case of frequency increase due to surplus active power in the power system, this relay will automatically shut down some generators according to the frequency increase value, so that the system’s frequency can be restored to normal levels. Over-frequency generator shut down function provides 5 stages.
Under-voltage load shedding function
In case of voltage decrease due to lack of reactive power in the power system, this relay will automatically shed some loads according to the voltage decrease value, so that system’s voltage is restored to normal levels. Under-voltage load shedding function provides 8 stages including 5 basic stages and 3 special stages.
Accelerated under-voltage load shedding function
In case of accelerated decrease in system voltage, this relay has the capability to accelerate load shedding according to dU/dt, so as to stop the system voltage decrease as early as possible. Thus, avoid voltage collapse, and restore voltage to optimal operating range.
Over-voltage protection function
In case of a voltage increase due to rising reactive power in the power system, this relay will automatically divide the system, so that system voltage can be restored to normal levels. The over-voltage protection function provides 3 stages.
df/dt and du/dt blocking functions
They are used to prevent possible undesired operations due to short circuit, load feedback, or abnormal frequency or voltage. Additional, blocking functions against VT circuit failure are also provided.
