Study of a new protection and control method for 22kV distribution system (Blocking relay method)

A spot network (SNW) or a normal-stand-by distribution system is mainly applied to the present 22kV distribution lines. However, mixture of those systems on a same distribution line is not practicable, because reverse power flow may cause an undesirable interruption of the network protector. In addition, an in-house generator, which produces reverse power flow may not be connected to the SNW system. Therefore, if this problem is solved, 22kV distribution system will be more widely used. This paper proposes a new protection and control solution for the above problems and introduces a configuration of a proposed protection and control system, detection principle of each relay and protection coordination between the relays.