JPS6120218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a computer-based direct control device for power system control, and particularly to improving control reliability when the computer is abnormal.

Generally speaking, the environment of electrical stations where computers are installed does not pose any problems under normal conditions, but in the event of a system fault, such as a one-wire ground fault due to lightning, a large current flows to the ground wire within the electrical station premises, causing As a result, the earth point potential rises abnormally, which is unfavorable for weak electrical equipment such as computers, and particularly under such conditions, computers may operate abnormally.

Therefore, when using a computer in a power system control device or the like, it is necessary to be able to control the computer even if it becomes abnormal.

The present invention is a direct control method using a computer that ensures the minimum necessary system control even if a computer operating abnormally is placed under the most severe environmental conditions when control is most needed.

Hereinafter, a detailed explanation will be given of a specific example of this method, taking as an example a load shedding and disconnection method that is used as a countermeasure against frequency drop when power systems are separated.

As shown in Figure 1, when power systems A and B are operated interconnected by interconnection line T, if an accident occurs on interconnection line T and both systems A and B are separated, In this case, the power P _T sent through the interconnection line T in the B system becomes insufficient, and the frequency in the B system decreases. As is well known, it is necessary to prevent a decrease in frequency from the viewpoint of vibrations of the turbine blades of the turbine generator, etc., and in the B system, load and disconnection are carried out urgently to resolve the shortage of power generation. , frequency recovery is usually performed. That is, it is only necessary to leave only the load lines that are equal to the total amount of power generated by the generators G ₁ to _{G o} in the B system and cut off the others.

Figure 2a shows the conventional control flow. Calculations are started at regular intervals, and when the system is not separated, each point of the interconnection line T, load lines L ₁ to L _o , etc. Capture the tidal flow and calculate the optimum load line and disconnected load line based on this. The calculation method is, for example, a combination of load line tides that match the tide flow P _T of the interconnection line T.

The control target load line calculated in this manner is stored. The above steps are performed at regular intervals for the ever-changing tidal current distribution, and only the optimum load and disconnection groups based on the latest tidal current distribution are memorized and calculated in advance when the system is separated due to a system accident, etc. , immediately disconnect the memorized load line.

Normally, as shown in Figure 2b, a load line break circuit is connected to contact 1, which closes when the system is separated (i.e., a trigger signal), and contact 2, which closes when the system frequency decreases (i.e., a fail-safe signal). The calculated and stored contact point 3 is used as a series circuit to send a disconnection signal to each line disconnector.

In such a conventional control device, in order to prevent unnecessary control from being performed when the computer part that calculates the optimal control line becomes abnormal, the conventional control device in Fig. 2b opens the contact 4. The control circuit was immediately locked.

That is, the output section of the control device is immediately locked in order to prevent a control command from being issued in a state where an incorrect line is stored due to an abnormality in the computer during normal operation.

This is a method that is commonly used in computer control equipment, but as mentioned above, in system control equipment at electrical stations in power systems, it is often used when control is most needed. Since computers are prone to malfunctions, conventional locking methods for devices have been inconvenient.

The present invention has been made in view of the above points, and
The purpose is to provide a control method that can be reliably controlled even when a computer malfunctions.

In the present invention, when there is an abnormality in the main part of a computer or other device, only the external storage circuit is immediately locked, and the control circuit is locked after a certain period of time (time required for control), thereby minimizing necessary control. The aim is to ensure that

FIG. 3 is a circuit diagram showing one embodiment of the present invention. In the same figure a, 10 is a digital computer, and the system conditions and data are inputted to the calculation unit via the input unit 11.
It is taken into the CPU. The CPU calculates the optimal line by the above-mentioned tidal flow calculation, and outputs it to the output relays 13, 13' via the output section 12.

Note that 16 is a relay that operates when the CPU is abnormal. In FIG. 1B, reference numeral 14 denotes an external storage memory, for example, a keep relay is used. 14C is a keep relay operating coil, and 14R is a return coil.

Now, keep relays are prepared as many as the number of lines to be controlled, and only the keep relays corresponding to the lines that are subject to disconnection are put into operation based on the calculation result of the optimum line disconnection.

For this reason, a contact 13a1 for operation commands and a contact 13a2 for return commands from the computer are connected to 14 as shown in the figure to record the CPU calculation results at regular intervals in the external memory 14. It is an output relay that operates, and 16a and 1
6b is a contact that is closed by the operation of the relay 16 or by another computer abnormality detection circuit, and under normal conditions, 16b is closed and 16a is open.

Contacts 1a and 1b are trigger contacts for control commands similar to those described in Fig. 2b, and for example, when the system is separated,
A is closed and 1b is open.

The control command circuit (right sequence in Figure 3b) is
As in the case of FIG. 2b, the trigger signal 1a, the fail-safe signal 2, the operation contact 3 of the breaker which is closed by the relay 14C of the keep relay 14 and opened by the relay 14R, and the sequence control contact 18
It consists of In the present invention, the normally closed time limit return contact 17b of the timer 17 is connected. Usually, a memory circuit consisting of 13a1, 13a2, and 14 is provided for each operating contact 3, respectively.
As a result, according to the present invention, the normally closed contact 17b of the timer 17 locks the disconnection control command circuit for a fixed period of time, whereas in the past, the disconnection control command circuit was immediately locked by the contact 4 in the event of a CPU abnormality. It does not lock for a while, but locks after controlling the controlled line held in the keep relay when it is healthy.

For example, if the lines held in a keep relay are not controlled all at once but are divided into several groups and controlled sequentially, 18 and 18' are sequentially controlled at regular intervals.
Control by closing the contacts. In such a case, the timer 17 is
All you have to do is make it work.

In this way, when a computer abnormality occurs, only the external storage circuit is locked immediately, and the control circuit is locked after the time required for control, thereby ensuring the minimum necessary control of the line to be controlled when the computer is in good condition. Become. According to the present invention, reliable control can be performed when the computer is most likely to malfunction.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an electric power system, Fig. 2 is a diagram showing an example of a load shedding command circuit and a flow of load shedding according to a conventional method to which the present invention can be applied, and Fig. 3 is a control circuit according to the present invention. 1 shows a configuration diagram showing an embodiment of the invention. 3, 3'...Shipping breaker control contact, 1...Trigger signal, 2...Fail safe signal, 17...Timer, 16...CPU abnormality detection contact, 14...
Keep relay.

Claims (1)

[Claims] 1. When the controlled part including the equipment that opens and closes is healthy, the opening/closing operation command for the equipment to be opened and closed when the controlled part becomes abnormal is constantly calculated, outputted via a rewriting circuit, and sent to the outside. A computer that is stored in a holding circuit and gives an opening/closing operation command to a device that performs the opening/closing operation of the controlled part based on the contents held in the external holding circuit when an abnormality actually occurs in the controlled part. When a computer error occurs, the external holding circuit is immediately prevented from being rewritten, and the external holding circuit is locked after a certain period of time required for the opening/closing operation device to operate, and the opening/closing operation command is stored. A computer control method characterized by preventing equipment from being opened or closed.