Chapter 5-3-11 Auto-prevention of Voltage Increase

Article 529. Required Functions of Auto-prevention of Voltage Increase

Auto-prevent voltage increase devices shall operate in allowable duration of over-voltage, and these devices shall be calibrated based on the duration and oscillation of over-voltage. Firstly, these devices shall energize shunt reactors.If power plant or transformersubstation have shunt reactor which is connected to the busbar directly without circuit breaker, or connection of reactor does not satisfy the requirement on decrease of voltage, these devices shall de-energize the line which cause unallowable voltage increase.

If necessary, values and direction of reactive power in power transmission lines shall be checked.

Chapter 5-3-12 Auto-prevention of Overload of Electrical

Equipment

Article 530. Required Functions of Auto-prevention of Overload of Electrical Equipment

Auto-prevention overload device shall reduce load of power plant.This device sheds load and divides power system, and, finally, de-energize overloaded electrical equipment. At this time, the measures to keep stability from being broken shall be taken.

Chapter 5-3-13 Remote Telecontrol Systems

Article 531. Required Functions of Telecontrol System

Remote control system includes remote control, remote signals, telemetry and control system.

Volume of electrical equipment to be controlled remotely shall be defined based on technical standard of a power sector or amounted volume of equipment.

Regarding the above, supervisory and control items of dispatch centers are shown in the Table531-1 for reference.

Firstly, remote control system is used for acquiring information on operation mode, conditions on main switchgear equipment and changes of status in case of electrical fault, and also used for checking the implementation of commands on energizing or de-energizing. Moreover, remote control

system also facilitates suitable operation for power system and equipment.

In order to select items to be observed or controlled in a substation withoutpermanent on-duty stuff, necessity of the items to be controlled or observed and ability tocontrol and observe of the remote control system shall be considered.

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Table 531-1 [Reference] Outline of supervisory and control items of load dispatch center system [Japanese case]

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Table 531-2 [Reference] Supervisory Items at Substation

Remote control system shall have necessary devices for setting operation mode of power system reliably and economically. For a power system with remote control system, remote control operation

as well as interruption by protective relays or automatic devices shall notrequire additional on-site operations.

As for large substations and power plants with many generators as well as power systems far from control center, if possible, remote control system should be equipped inside such power systems.

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Quantity of remote control equipmentshall satisfy the requirement on control method of each power system.

As for electrical equipment to be controlled remotely by one load dispatch center, the operation procedures by operator shall be the same among such electrical equipment.

Article 532. Information Signal Requirements

Remote signals from power systems under control and observation by some load dispatch centers shall be regularly transmitted to higher level load dispatch centers by forwarding or transmitting the signals selectively from lower level load dispatch centers. Such signals are usually transmitted with no more than one forwarding level.

In order to transmit remote signals on conditions and status of electrical equipment,auxiliaryon contact of electrical equipment or contact of repeat relay shall be used.

Article 533. Required Functions of Remote Control Systems

Main parameters on electricity or operating condition are indispensable for selecting and setting optimal operation mode of entire power system as well as preventing or removingelectrical faults which occurs in power system. Telemetry on salient parameters as well asnecessary parameters shall

be transmitted, accumulated and recorded continuously.

Telemetry to higher level load dispatch centers should be transmitwitedh no more than one forwarding level. As for parameters which don’t need to be checked frequently, telemetry shall be carried out periodically or by request from operator.

In order to implement telemetry, requirement on onsitedata reading shall be considered.Generally, sensors used for metering on site should be placed on meter panel as long as sufficient measurement accuracy is ensured.

Article 534. Requirements for Communication Lines

Telemetry on necessary parameters for frequency and power flow auto-control system shall be carried out continuously.

Long communication and signal line for metering power flow and transmitting remote control signals to major power plant or group of power plants should be equipped with double independent remote control channels.

Remote control equipment shall have protective relays which can interrupt auto-regulation system in case that fault occurs inside the equipment or remote control channels.

Remote control equipment shall be capable of providing changeover function between remote control and on-site control in the following cases.

-Simultaneous interruption of all remote control circuits and remote signals by devices which can display the interrupted circuits clearly.

-Interruption of all remote control circuits and remote signals of each component by special cramp

bank, testing box and other devices which can display the interrupted circuit clearly.

Measuring equipment such as sensors (including remote measurement sensors) fixed at the electrical measurement instruments shall be installed in accordance with equirementthe on measuring electricity.

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