Protection and control system, protection and control device, and merging unit

A protection and control system, comprising:

• a first merging unit which obtains an electric variable from a transformer installed in an electric power system, and digitally converts the obtained electric variable to output as first electric variable information to a first network;
• a second merging unit which obtains the electric variable from the transformer installed in the electric power system, and digitally converts the obtained electric variable to output as second electric variable information to a second network;
• a first protection and control device which obtains the first electric variable information from the first merging unit through the first network, judges whether or not a system fault occurs in a zone to be protected of the electric power system based on a predetermined relay characteristic, and outputs a main trip information to the first network when that the system fault occurs is judged;
• and
• a second protection and control device which obtains the second electric variable information from the second merging unit through the second network, judges whether or not the system fault occurs in the zone to be protected of the electric power system based on a plurality of the relay characteristics which are predetermined as respective fault detection relays of the first protection and control devices, and outputs FD trip information to the first network when that the system fault occurs is judged,
• wherein the first merging unit judges opening or closing of a circuit breaker or a switch which is installed in the electric power system based on the main trip information and the FD trip information.

A protection and control system, comprising:

• a first merging unit which obtains an electric variable from a transformer installed in an electric power system, and digitally converts the obtained electric variable to output the converted electric variable as first electric variable information to a first network;
• a second merging unit which obtains the electric variable from the transformer installed in the electric power system, and digitally converts the obtained electric variable to output as second electric variable information which is different from the first electric variable information to a second network;
• a plurality of first protection and control devices, each of which obtains the first electric variable information from the first merging unit through the first network, judges whether or not a system fault occurs in a zone to be protected of the electric power system based on a predetermined relay characteristic, and outputs a main trip information to the first network when that the system fault occurs is judged;
• a second protection and control device which obtains the second electric variable information from the second merging unit through the second network, judges whether or not the system fault occurs in the zone to be protected of the electric power system based on a plurality of relay characteristics which are predetermined as respective fault detection relays of the first protection and control devices, and outputs FD trip information to the second network when that the system fault occurs is judged;
• and
• a cable to connect the first merging unit and the second merging unit,
• wherein the first merging unit judges opening or closing of a circuit breaker or a switch which is installed in the electric power system based on the main trip information outputted from the first protection and control devices and the FD trip information outputted from the second protection and control device through the cable.

A protection and control device, comprising:

• a transmission processing unit which receives, from a merging unit which obtains an electric variable from a transformer installed in an electric power system, and digitally converts the obtained electric variable to output as electric variable information, the electric variable information through a network;
• and
• a relay calculating unit which judges whether or not a system fault occurs in a zone to be protected of the electric power system based on the electric variable information obtained from the transmission processing unit and a plurality of relay characteristics which are predetermined as respective fault detection relays of a plurality of first protection and control devices each having a specific relay characteristic, and outputs FD trip information to the transmission processing unit when that the system fault occurs is judged,
• wherein the transmission processing unit outputs the FD trip information obtained from the relay calculating unit to the network.

A protection and control device, comprising:

• a first transmission processing unit which receives, from a merging unit which obtains an electric variable from a transformer installed in an electric power system, and digitally converts the obtained electric variable to output as electric variable information, the electric variable information through a first network;
• a relay calculating unit which judges whether or not a system fault occurs in a zone to be protected of the electric power system based on the electric variable information and a predetermined relay characteristic, and outputs FD trip information when that the system fault occurs is judged;
• and
• a second transmission processing unit which outputs the FD trip information obtained from the relay calculating unit to a second network,
• wherein the relay calculating unit judges based on a plurality of the relay characteristics which are predetermined as respective fault detection relays of a plurality of protection and control devices connected to the first network or the second network.

A merging unit, comprising:

• an input converter which obtains an electric variable detected by a transformer installed in an electric power system;
• an A/D converter which digitally converts the electric variable obtained by the input converter as electric variable information;
• a transmission processing unit which obtains the electric variable information from the A/D converter to output to a network;
• and
• a trip command output unit which judges whether or not to open a circuit breaker or a switch which is installed in the electric power system;
• wherein the transmission processing unit obtains main trip information outputted from a plurality of first protection and control devices each having a predetermined relay characteristic and FD trip information outputted from a second protection and control device having a plurality of the relay characteristics which are predetermined as respective fault detection relays of the first protection and control devices;
• and
• wherein the trip command output unit judges opening or closing of the circuit breaker or the switch based on the main trip information and the FD trip information.