JPS5920262B2 - Automatic synchronization digital control system between multiple electric stations, multiple centers, and electric stations - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention enables high-performance system control in a power system.

In other words, all the specifications necessary for system control, such as AC voltage, AC current, and the status of each equipment, are converted into automatically synchronized digital codes to improve accuracy, which is then collected by a processing device and used for calculations, etc. By performing this processing, it is possible to improve the performance of system-related protection, automatic adjustment, remote monitoring operations, etc., as well as automatic recording, automatic statistical creation, etc., as shown in (to) to ← below, or in other words, increase the speed of control. This enables high reliability and high automation.

(b) Determination of the hot water area in the event of a system accident and protection of the area where the accident occurred. (p) Automatic adjustment of generator output distribution and system current, etc., necessary to maintain voltage, frequency, and system stability.

(-U) Remote monitoring and operation of power equipment.

←) Automatic recording of various 111 values necessary for system planning and operation, automatic statistical creation necessary for power equipment management, etc.

This automatic synchronization digital control system automatically samples AC voltage and AC current in all systems at a constant period and at the same time, synchronizes and collects all input codes, including these automatic synchronization digital codes.
This is a transmission and processing method.

Conventional system control has been performed as shown in Figure 1.

In other words, the voltage and current in the electrical circuits of the system necessary for various protection, adjustment, and monitoring operations are determined by winding the primary and secondary windings around each core of the voltage transformer (PT or PD) and current transformer CT. A method is used to collect the analog output of each device using a dedicated cable.
) A method is adopted in which inputs such as the open/close status of power equipment such as line switch LS are collected and processed using dedicated cables. However, as electric power systems become larger and more complex, the devices used for control using this analog system become more complex.
In addition, as high performance has been required for these functions, serious defects such as the following are becoming apparent.

1 Problems with system voltage and current extraction Various control devices such as protective relay devices and monitoring and operation devices require data such as system voltage and current as input.
Therefore, each transformer must have a large output for the following reasons.

6. Direct consumption of the output of the transformer as the driving force for each device (including measuring instruments).

6. Since the transmission is over a considerable distance (sometimes several hundred meters) from the transformer to the control room where the above devices are installed, if the output is small, the analog input is easily affected by noise.

Therefore, in order to obtain a high output transformer, it is necessary to interpose an iron core with high magnetic permeability as a magnetic medium between the primary winding and the secondary winding.

Iron has a high magnetic permeability and is an excellent material for obtaining a high output transformer, but on the other hand, it has the disadvantage of causing large errors in the secondary output as described below.

That is, when a magnetizing current exceeding a certain level flows, the amount of magnetic flux becomes saturated, and a phenomenon occurs in which the magnetizing current and the amount of magnetic flux are no longer proportional (saturation phenomenon). This is further promoted when the primary current includes a direct current component.

In addition, when a large current such as a short-circuit current is abruptly interrupted on the primary side, a phenomenon in which magnetic flux remains (residual magnetism phenomenon) occurs, and as a result, the fidelity of the secondary side voltage and current is lost. There are many.

In an attempt to reduce these errors, the magnetic flux density of the iron core is lowered, and even if a huge iron core is used to prevent saturation, there is a limit in the actual system because there is a difference of several tens of times between the normal current and the fault current, and there is a limit to the ability to handle large currents. It is difficult to reduce the error in .

2. Transmission Problems In order to faithfully transmit the transformer output to various control devices, consideration must be given to the cables that connect the transformer and the control room.

If this cable is thin, the transformer output will be lost here, increasing the error.

Until now, in the design of 275,000 volt class electric power stations, the power equipment is large and the area required for the electric power station is large, so long cables are required. The rated current of the secondary winding is 5 amperes.
Measures have been taken to reduce the load on the transformer, such as lowering the amperage.

However, if a 500,000 volt class electricity station were to be needed, as is the case now, the length of cables laid within the premises would have to be approximately doubled.

Moreover, if the rated current of the secondary winding of the current transformer is to be lowered to 1 A or less, the voltage between the terminals will increase in inverse proportion to this. For this reason, it is necessary to increase the withstand voltage design of the control device compared to the conventional one so that there is no problem even if a short circuit current flows on the primary side.
Increasing the size of the device becomes unavoidable.

Therefore, it is actually impossible to reduce the rated current to 1A or less, and a cable twice as thick is required. In addition, various control devices are required to have advanced functions, and instruments,
As the number of relays increases, the number of meters and relays differs depending on the purpose of use, such as reducing errors below the rated value and having saturation characteristics in the overcurrent range, while protective relays reduce errors in the large current range in the event of an accident. Characteristics become sought after.

As a countermeasure to this, it became necessary to separate the secondary windings of CTs according to their uses, as shown in Figure 6 (current 500,000 volt CTs use a 5-core type), and as a result, the number of control cables also increased. However, although the amount of copper has increased significantly, it is still becoming difficult to maintain the required accuracy.

Further, as power systems become more complex, it is necessary to mutually receive and receive the secondary side output of the transformer with other remote electric stations for system protection and adjustment.

In this case, if analog quantities are transmitted using microwave radio links, power line carriers, etc., they are likely to be adversely affected by noise and level fluctuations, so even today, analog quantities are converted and transmitted. However, on the receiving side, the extra step of converting back to analog is now necessary, making the transmission equipment unavoidably complicated. 0 Processing Problems Conventional various control devices have various functions such as reference setting voltage, comparison of current value and circuit voltage, current, composite comparison of two or more circuit currents, phase comparison of circuit voltage and current, calculation of active power, etc. For calculation processing, the output of the transformer is used in its analog form.

As the system becomes larger and more complex, these devices are required to have advanced functions, and the calculation processing within the devices becomes more complex.
Arithmetic operations on analog quantities produce errors each time they are processed, and as the complexity increases, the errors accumulate, so it is becoming virtually impossible to obtain functions greater than those currently available using analog methods. In addition, the effects of an accident in a part of the system are becoming extremely large, and it is becoming impossible to expect a stable power supply with the conventional protection system for each part of the system.

One way to deal with this is to use a protection system for each section facing electrical stations, and to collect data on voltages, currents, etc. from many important electrical stations in the entire system in one place and make systematic and comprehensive judgments to prevent accidents. A wide-area protection method that determines the disconnection point can be used, but when this method is used with analog quantities, the errors of the transformers in each part of the system are different, so the total error is large, and it is difficult to achieve the required performance. What you want is impossible.

Furthermore, digital quantities can be processed by either software or hardware, but analog quantities are difficult to store and can only be processed by hardware, which requires specialized equipment for each control function. The device becomes complicated and large, and the required space becomes large.

Furthermore, when a new control function is required due to a change in the electric power system, it is necessary to design and manufacture the device each time, resulting in a lack of flexibility.

This method solves the three main problems listed above, and enables high speed, high reliability, and high automation of various types of control. The case where the electric station equipment of the synchronous digital control method is used alone and the case where the electric station equipment are placed opposite each other will be specifically explained, and the case where the center unit is provided in FIGS. 4 and 5 will be explained in detail.

(1) Explanation of the case of the electric station equipment alone according to FIG. 2.

As shown in Figure 2 A, among the power equipment of the electric station (power generation and substation), PDl, PD2..., CTl, CT2, C
The voltage and current analog outputs of T3, etc., respectively enter the automatic synchronization digital encoder 1. Here, the sampling synchronization signals in each of these automatic synchronization digital encoders 1 operate automatically in synchronization with the automatic synchronization adjuster 2 installed in the control room, for example, and operate in constant synchronization and at the same time. sampled and digitally coded. The automatic synchronization between the automatic synchronization adjuster 2 and each automatic synchronization digital encoder 1 will now be explained assuming that 2 is selected as the parent, as shown in FIG.

This explanation is exactly the same regardless of which automatic synchronization digital encoder 1 is selected as the parent.

As shown in Figure 2, the delay time τa for sampling synchronization is set to τ
a sampling period τo - delay time with the main regulator τ1
The sampling times of the CT and PD points are also delayed by τo by the automatic synchronization controller 2 in the control room.

That is, the automatic synchronization adjuster 2 transmits a sampling time signal, and the automatic synchronization digital encoder 1 receives this sampling time signal and performs sampling using the sampling synchronization signal delayed by τa in the automatic synchronization adjustment circuit. do.

(Refer to Figure 7) In this case, since it is within the same electrical station, τ
1 is an extremely small time, but when synchronizing the sampling time with other electrical stations or center equipment, τ1 is τ.

It can be larger than. In times like this τa=n・τo−τ1 (n is an integer) Adjust so that

By the method described above, each automatic synchronization digital encoder 1
operates so that the sampling times of the input analog quantities are the same.

Further, the operation of the automatic synchronization digital encoder 1 will be explained using FIG.

That is, FIG. 7A shows the external appearance of the CT, and the opening of the same figure shows a block diagram of the automatic synchronous digital encoder.

The voltage or current analog amount on the secondary side of the transformer is determined by the sampling synchronization signal taken out from the automatic synchronization adjustment circuit 23 by the sampling circuit 24, and the 10th to 2nd of the commercial frequency waves.
It is sampled to the extent that it can reproduce up to the 0 harmonic component.

This output is further converted into a fixed digital code, such as a time division multiplex cyclic method, through an analog-to-digital converter 25 and a bipolar converter 26 (or a carrier wave FS modulation method, etc.).

Various inputs such as CB2, CB3, etc. that represent the open/close status of power equipment, the operating status of the load voltage regulator LR, the usage status of phase adjustment equipment, etc. are also linked to the respective main circuits. The signals are detected by the auxiliary switch, and are converted into fixed digital codes using the time-division multiplex cyclic method, similarly to the analog inputs, through the scanning mechanism and bipolar converter of the digital encoder 3.

In this case, the input signal indicates the open or closed state or the adjustment tap number 1, and unlike analog quantities such as voltage and current that change from time to time, b1 remains the same for at least the order of seconds, so sampling is not required. No synchronization is required. Each of the cyclic codes arranged in series in the automatic synchronization digital encoder 1 and digital encoder 3 performs error correction, temporary storage, classification, organization, distribution, etc. of the data via a coaxial cable installed within the premises of the electric station. The information is collected in the connection control device 4. Furthermore, the connection control device 4 calculates and creates various data such as active power, reactive power, and electric energy based on the collected voltage and current data, and frequency data based on the in-house power supply, and temporarily stores these data. The data is sequentially transferred to the main storage device 5 for high-speed processing or the main storage device 6 for low-speed processing according to the purpose of use.

In the main storage devices 5 and 6 for high-speed and low-speed processing, stored data is classified into high-speed processing devices 7 for busbar and transformer protection, and low-speed processing devices 8 for accident recovery, centralized control, etc. .

The high-speed processing device 7 uses the data stored in the main storage device 5 to perform digital arithmetic processing according to programs created for specific purposes such as bus bar, transformer protection, power transmission line back-up protection, and the like. As described above, this arithmetic processing uses data whose sampling times for analog quantities are automatically synchronized, so that the arithmetic processing can be greatly simplified.

Therefore, the scale of the processing device can be reduced accordingly. If synchronous operation is not performed, it is necessary to set the number of samplings to a very large value, or to perform complex calculations in the calculation process, such as waveform reproduction calculations when expressed in analog terms, and the scale of the processing device becomes large.

The low-speed processing device 8 uses the data stored in the main storage device 6 to perform digital arithmetic processing according to programs created for specific purposes such as accident recovery and remote control.

Among the calculation results of the high-speed and low-speed processing devices 7 and 8, the C
When an output for opening/closing B, adjusting LR, controlling phase adjustment equipment, etc. is generated, various control outputs are sent to the corresponding power equipment via the output interface 9.

In addition, the above-mentioned control and adjustment arithmetic processing data and state change data of power equipment are stored in the main storage devices 5 and 6, and the input/output control device 10 displays or records the output and categorizes them, and the monitoring and control device 11 or Output to the recording device 12.

In addition, if manual operation is required as a result of monitoring and recording, the monitoring and control device 11 is used to manually perform opening/closing and adjustment operations. The data processing status monitoring control device 13 monitors the linked program operations among the main storage devices 5 and 6, the high-speed processing device 7, the low-speed processing device 8, and the input/output control device 10, and if an abnormality occurs in the operation, Performs control such as switching to a shared preprocessing device.

l-) Electrical station equipment according to Figures 2 and 3 Explanation for opposing cases.

In the case of opposing electrical station equipment in the scope of this patent claim, as shown in FIG. ) and transmitting data used for power transmission line protection, etc., and adds a new power transmission line protection function to the control function of the electric station equipment alone as described in section () above.

This added portion is shown in dotted lines in FIG. That is, for example, current data necessary for protecting a power transmission line between opposing electric stations is transmitted from the connection control device 4 to the other end via the communication control device 14 and the data modulator/demodulator 15. At the same time, current data from the other end is also collected to the connection control device 4 via the same route. In this case, since it is necessary to make the data sampling time the same with the opposite electric station, the synchronization data of the automatic synchronization controller 2 is also exchanged through the same route. The other end current data collected by the connection control device 4 is transferred to the main storage device 5 for high-speed processing together with the current data of the own end.

The high-speed processing device 7 uses these current data stored in the main storage device 5 to perform digital arithmetic processing according to a program created for power transmission line protection.

As a result of the calculation, if a control output to open a CB is generated due to an accident inside the protection zone, an open command signal is sent to the corresponding CB via the output interface 9. Further, this open output data is stored in the main storage device 5 and outputted to the supervisory control device 11 and the recording device 12 via the input/output control device 10.

Further, the high-speed processing device 7 outputs a re-closing output after 0.4 to 0.8 seconds according to a re-closing program based on the CB opening data, and sends a re-closing signal to the corresponding CB. The series of operations described above for protecting the power transmission line, disconnecting it, and reclosing it are exactly the same at the other end.

The results of these operations are mutually transmitted from the high-speed processing main storage device to the other terminals via the communication control device 14 and data modulator/demodulator 15 for monitoring and recording. (ID 4th
Explanation of the case where there is a center device according to FIG. 5.

If there is a center according to the claims of the present invention, as shown in FIG. It performs control related to the entire system, which will be explained next.

FIG. 4 shows an example of the functions of the center device.

The communication control device 14 in the figure classifies various types of data that are input and output through the shared modem 15 into high-speed and low-speed data and distributes them as follows.

O Data used at the center Data transferred from one electrical station to another O Data used between centers Among these, original data such as current and voltage used at the center, processing of accident recovery, centralized monitoring control results, etc. Data is transmitted to main storage devices 18 and 19 for high-speed and low-speed processing, respectively.

The data transferred from one power station to another is current data for power transmission line protection when the power station equipment is facing each other, and the data used between centers is transferred to other center equipment as described below. This is mutually linked data when provided.

The main storage device 18 for high-speed processing stores current data of each electrical station used for wide area protection.

The high-speed processing device 20 uses these data to monitor the power transmission system over a wide area, and when an accident occurs, it performs digital calculation processing according to a program created to minimize the section where power transmission is stopped due to the accident. . The main storage device 19 for low-speed processing stores data such as the voltage of each electric station, reactive power, operating status of phase modifier equipment, opening/closing status of shield breakers, control results of accident recovery operations, and centralized monitoring control results. .

The low-speed processing device 21 uses these data to perform digital arithmetic processing according to a program created for each purpose, such as voltage reactive power adjustment control, power transmission line/bus bar overload control, etc.

When an output is generated as a result of calculation, such as opening/closing a circuit breaker or controlling a phase modifier, the control output is sent to the circuit, circuit breaker, phase modifier, etc. via the following processing route.

Processing devices 20, 21→main storage devices 18, 19→communication control device 14→data modulator/demodulator 15 for controlled power generation/substation
→ Data modulator/demodulator 15i of the controlled power generation/substation Communication control device 14 → Main storage devices 5, 6 → Output interface 9 Also, the main storage devices 18, 19 store arithmetic processing data for each of the above controls and status change data of power equipment. The input/output control device 30 displays or records the output, categorizes it, and outputs it to the supervisory control command device 31 or the recording device 32.

If manual operation is required as a result of monitoring and recording the death, the monitoring control command device 31 is used to manually perform opening, closing, and adjustment operations. The operation output route in this case is as follows. Supervisory control command device 31 → input/output control device 30 → main storage device for low-speed processing 19 → communication control device 14 → data modulator/demodulator 15 for controlled power generation/substation → data modulation/demodulator 15 of controlled power generation/substation → communication control Device 14 → Main storage device 6 for low-speed processing →
Output interface 9.

Further, the display contents of the supervisory control command device 31 and the recorded output of the recording device 32 in the center device are outputted as display or recorded output to the supervisory control device 11 and the recording device 12 of the electric station equipment.

The data processing status monitoring control device 33 is a main storage device 10
8, 19. Monitors the linked program operations between the high-speed processing device 20, the low-speed processing device 21, and the input/output control device 30, and controls such as switching to a shared preliminary processing device if an abnormality occurs in the operation. Let's do it.

As described above, the automatic synchronization digital control system of the present invention is a system in which all inputs and outputs to the control unit are automatically synchronized digital codes, and digital arithmetic processing is performed.
The following effects eliminate various defects in the conventional analog system, and increase the speed of the 20 control system.
This enables high reliability and high automation.

The specific effects of the present invention will be described below.

I. Effects of using a digital transformer (a) The load on the secondary winding of a digital transformer can be made extremely small by requiring only the amount required for digital coding, which eliminates the large errors caused by magnetic saturation and residual magnetism, which were previously possible. It does not require an iron core, which was a factor, and unlike conventional transformers, it is possible to obtain a complete output for each application no matter what is connected to the digital output side.

Therefore, there is no need to consider the metamorphic ratio error at all, and there is no need for a complicated method of how to avoid this error as in the past, and a control system based on an extremely easy-to-understand principle can be adopted.

(b) Since a heavy iron core and winding are not required, in the case of a current transformer, the winding part can be placed at the top of the insulator tube as shown in Figure 7A, and the conductor of the primary winding can be is very short and good.

In particular, with large current current transformers, when the winding section is placed below the insulator tube as in the conventional type shown in Figure 6, there are problems such as a decrease in accuracy due to leakage magnetic flux and dissipation of the amount of heat generated, but these problems have been solved all at once. In addition, it is possible to reduce the size and weight.

Voltage transformers can also be made smaller and lighter because the capacitance of the capacitor that divides and extracts the voltage can be extremely small.

c) Fine cables can be used from the transformer to the various control devices without putting a burden on the transformer.

Moreover, since digital codes are easy to memorize, it is possible to time-division multiplex the codes and transmit them in series.This allows several transformers to be grouped together for synchronization adjustment and cables for automatically synchronizing digital code transmission. Two pairs may be installed between the detection end and the control room.

Specifically, an ultra-high voltage substation (12 transmission lines, 8 transformers,
Taking as an example a 4-bus bus (considered standard), and comparing the amount of copper in the cables inserted here, Figures 1 and 2
As is clear from the number of connecting cables shown in the figure, this method requires only one-fortieth of the conventional method (approximately 16 tons vs. 0.4 tons), and the construction work is also easier.

Effects of adopting digital codes.

a) Even if distortion occurs due to noise during the digital code transmission and processing process, it can be shaped and does not cause errors, making it possible to easily realize systems with complex functions with high accuracy.

b Even if a digital code makes an error due to noise, it can be detected and corrected easily in a very short period of time, so it is not possible to detect an error by looking at the behavior over a certain period of time like with conventional analog quantities. There is no need to judge the presence or absence.

Therefore, a highly reliable and high speed control system can be obtained.

Since digital codes are easy to store, there is no need to separate the data to be transmitted depending on the purpose of use, and the data can be shared.

Therefore, compared to analog systems, the transmission capacity of microwave radio circuits and the like can be significantly streamlined. Effects of adopting digital processing equipment [Analog systems lack flexibility in storage and input/output conditions, so many dedicated devices were required for each control purpose, but with this system, a single device can perform multiple functions using software. You can have it.

Therefore, taking the same ultra-high voltage substation as above as an example, and calculating the number of required devices, we find that in the conventional analog system, as shown in Figure 1, there are transmission line protection devices, transmission line back-up protection devices,
There are approximately 100 racks including busbar protection equipment, transformer protection equipment, automatic recovery equipment, remote monitoring and control panels, ultra-high-speed transmission equipment, low-speed transmission equipment, and micro radio equipment.
As shown in the figure, approximately 10 units, such as data processing equipment, main storage for high-speed and low-speed processing, connection control equipment, communication control equipment, high-speed and low-speed transmission equipment, and micro wireless equipment, are used, which is about 1/10 of the total. This makes it possible to greatly simplify the equipment. Furthermore, the amount of construction work will be reduced and made easier. There is no need to design and manufacture the b-processing device each time depending on the purpose of use, and mass-produced standard products can be used, resulting in significant improvements in reliability and economy.

c. Previously, when a new function control method was required, it took a lot of time to design, manufacture, and test repeatedly.
There is no need to develop hardware for processing devices such as computers, and the development is based on software, so it can be realized very quickly.

d Additions and changes to control devices related to new installations and changes to power systems were conventionally large-scale construction work that required complex skill, but with this method, additions and changes to software are the main tasks, so this is also extremely easy. It is.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a conceptual diagram of a wiring diagram of an example of a conventional system control system and its equipment arrangement. FIGS. 2A, 2B, and 2C are a wiring diagram of an automatic synchronization type digital control system according to an embodiment of the present invention, an explanatory diagram of automatic synchronization sampling thereof, and a conceptual diagram of the state of the apparatus. FIG. 3 is an example of the configuration of an automatic synchronization type digital control system for electrical stations according to the present invention. FIG. 4 is a wiring diagram of an automatic synchronization type digital control system with a center device according to the present invention. FIG. 5 is an example of the configuration of an automatically synchronized digital control system using an electrical station group and a center according to the present invention. 6th
The figure is a conceptual diagram of the structure of a conventional current transformer CT. FIGS. 7A and 7B show an example of a structural conceptual diagram of a digital current transformer and an example of a block diagram of an automatic synchronizing digital encoder to which the present invention is applied. 1. Hakudo synchronous digital encoder, 2
・・Hakudo synchronous adjuster, 3・・Digital encoder, 4・
...Connection control device, 5...Main storage device for high-speed processing, 6
. . . Main storage device for low-speed processing, 7. . . High-speed processing device,
8... Low-speed processing device, 9... Output interface, 10... Input/output control device, 11... Monitoring control device, 12... Recording device, 13... Data processing status monitoring control device , 14... Communication control device, 15... 7 data modulator/demodulator, 16... Control device, 17... Center device.

Claims (1)

[Claims] 1 Corresponding to the quantity of electricity for detecting an analog quantity proportional to the quantity of electricity that changes continuously, such as voltage, current value, etc. in the power system connection at each of multiple electric stations included in the electric power system. a plurality of detection means, a plurality of sampling/digital conversion means located next to these detection means and for sampling the instantaneous value of the analog quantity, converting it into a digital code and transmitting it; and a control room or An automatic synchronization adjustment means provided at the center for transmitting and transmitting a sampling time signal, and receiving this sampling time signal, perform sampling by the sampling digital conversion means at a constant period and at the same time in all the sampling digital conversion means. A means for time-delaying the sampling time signal so that the sampling time signal is transmitted between multiple electric stations or Automatic synchronization digital control system between multiple centers and electrical stations.