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A new substation integrated automation scheme

Abstract: This paper expounds the integrated automation technology using AC 220V operating power supply. Based on the careful analysis of the electrical principle, this paper introduces several main features of the system under the close cooperation with the designers of automatic and double clutch transmissions and the four remote (telemetry, remote signaling, remote control, remote adjustment) functions of the system, which is a feasible new comprehensive automation scheme for substations

key words: substation integrated automation protection configuration

0 introduction

with the implementation and promotion of the western development strategy, the power system has increased the investment in the rural power supply system, built substations in the newly planned areas in rural areas, and transformed the old substations to varying degrees, so as to improve the quality of rural power consumption. In the rural power bidding project of Shaanxi Province in 2000, we won the bid for all the secondary protection projects of eight substations. For the protection configuration of these eight substations, the integrated automation technology of AC 220V operating power supply is adopted, and the integrated automation operation of the substation is successfully realized by using the existing complete set of integrated automation monitoring devices

1 electrical principle analysis

1.1 the operating power supply of the power supply part

substation is the power supply required for the operation of relay protection, automatic devices, signal devices and circuit breakers. 220V DC is traditionally used as the operating power supply. The commonly used DC operation power supply is the battery DC power supply system. Although it is an independent DC power supply, it can work reliably in the case of power failure in all substations, and it can also provide accident lighting, which has also been applied in large substations. However, due to the large investment, high maintenance cost, complex operation and huge volume of battery pack, the application of DC power supply system in agricultural integrated automation control system is limited to a great extent. Therefore, it is necessary to carry out technical innovation on the power supply system

to transform the substation integrated automation control system, we use AC 220V operating power supply to replace DC 220V operating power supply, so that the substation saves a set of DC power supply equipment and saves more than 200000 yuan for the substation. Therefore, this system is both economical and practical in agricultural transformation. The substation only needs to be equipped with a set of UPS power supply, which can provide working power supply for the protection, measurement, control and monitoring system. In the case of power failure of the substation, UPS can also maintain battery power supply for 30 minutes, and also provide emergency lighting. The operation reliability of the substation is greatly improved

1.2 control circuit part

the opening and closing control of the circuit breaker in the substation is realized through the control circuit of the circuit breaker. In order to realize the opening and closing operation of the circuit breaker, it is necessary to have an actuator that can perform the opening and closing, that is, the operating mechanism of the circuit breaker; It must also have a control mechanism that can send opening and closing commands, that is, a control switch. The electrical connection circuit between the control mechanism and the actuator is called the control loop. The control circuit of DC operation power supply is shown in Figure 1

Figure 1 circuit breaker control circuit with anti tripping device

it can be seen from Figure 1 that the biggest feature of the DC operation control circuit is that the bus voltage is all DC 220V, and an anti tripping locking relay is added to the control circuit to prevent the 5 and 8 contacts or reclosing contacts of the control handle KK from being closed after being closed for too long, and there is a short-circuit fault on the line at the moment of closing the circuit breaker, At this time, the relay protection immediately acts and trips. Since the 5 and 8 contacts of KK have not been separated after tripping, the circuit breaker may have multiple "tripping closing", which is not allowed

the control circuit of AC operation power supply is shown in Figure 2. Compared with the circuit breaker control circuit of DC operation power supply, the tripping and closing signal circuit in the control circuit is composed of the internal 24V power supply of the protection device connected to the normally open contact of the internal tripping and closing relay of the device, and then connected in series with the indicator light. The external power supply +24v marked in Figure 2 is a DC power supply separately configured for the protection screen, with a power of 40W, which can meet the power requirements of the signal circuit of the whole substation; The voltage of the control bus is the AC 220V voltage inverted by UPS, which acts reliably in the actual commissioning process

1.3 sound unit part

the signal of each protection unit is transmitted to the upper computer through the RS-422 interface of the unit, and then the upper computer transmits the signal to the protection sound unit to send out an audible alarm

2 main features of the system

2.1 technical features of the system

a. fast data update speed (important data update cycle is less than 2S)

b. the general data update cycle is not more than 5S, and the secondary data cycle is less than 10s

c. in case of accident, the transmission time of remote signaling displacement is less than 2S

d. the transmission time of remote signaling and remote adjustment commands is less than 1s

e. the real-time response time of picture call is less than 3S

f. the refresh cycle of real-time data of the picture is less than 5S

g. the accuracy of remote signaling processing shall not be less than 99.9%

h. the accuracy of remote signaling and remote adjustment shall not be less than 99.9%

i. the system availability is not less than 99.9%

j. mtbf>1000h

2.2 characteristics of information organization principles

the integrated automation system has advanced and feasible communication ports, strong remote transmission function, and accurate and timely communication with centralized control stations and dispatching centers. It is mainly reflected in the following points:

A. It can interface with microwave optical fiber spread spectrum and other communication methods

b. the communication between the system and the county-level dispatching and monitoring system can adapt to a variety of communication protocols, mainly the ministerial CDT, and can easily replace and expand other communication protocols such as asynchronous polling, dn3.0

c. the communication interface between the monitoring system and the on load voltage regulating mechanism of the main transformer and the electronic multi-function electricity meter is provided

d. the control handle with mechanical program lock is installed on the protection control panel to realize the locking function of technical parameters

e. this system provides a communication interface with the microcomputer locking software, and the two share a common operation platform

2.3 functional characteristics of the automation system

a. the system has a good man-machine interface, and all windows and operations are Chinese. It can accurately monitor the operation status of the substation in real time; It can also monitor the operation status of the integrated automation system; The actual status of all power units can be monitored synchronously on the upper computer; It can accurately and timely record events, summarize, classify, transmit or report various charts, and has the function of drawing and printing

b. the system has self-test function, and all software and hardware can be checked (including communication ports). The failure of a single unit will not cause maloperation of the device, and will not affect the operation of other units. It can automatically determine whether it is necessary to lock relevant functions or equipment according to the nature of the failure, and send out failure alarm signals at the same time

c. the system software has good modifiability, which can easily increase or decrease or change software functions and facilitate upgrading. Its modification operation also has password locking

d. the system can realize the automatic collection, storage, processing and transmission of all information of the whole station

e. the measurement, calculation and transmission accuracy of the system meet the relevant requirements

f. the whole system has four remote functions: direct AC sampling, report information to the dispatching center, and receive information and commands from the dispatching center or county dispatching

g. the setting value of protection can be modified or offline, and can be adjusted remotely and locally. Password locking is required to modify the setting value

h. set the strong current one-to-one "opening" and "closing" control functions, and realize the mutual locking of remote and local operations, so that the microcomputer control or communication system can still be operated and operated in case of failure

2.4 characteristics of monitoring system

the nas-811 integrated automation system developed by us has the functions of data collection, processing, transmission, fault alarm, fault recording, fault analysis, fault display, event recording, accident recall, chart printing, call printing, operation demonstration and so on; Color CRT has a variety of multi frame displays, various window operations, software localization, etc. 16 bit industrial control computer is adopted, equipped with 1 piii550mhz/64m/15g host, 1 17 inch color CRT, 1 keyboard and 1 mouse, 1 printer and 1 UPS power supply. The monitor has multimedia function and is configured with standby communication interface

a. it realizes the comprehensive monitoring and recording of whether all the operation conditions of the whole station can achieve breakthroughs in battery technology, including: system main wiring diagram, equipment state diagram, load curve, voltage curve, voltage bar diagram, operation parameter table, fixed value table, analog quantity out of limit, switch displacement alarm, protection action alarm, Call and print of historical parameters (analog quantity, electrical measurement, event sequence record, switch accident trip, protection action time, protection setting modification time, adjustment times, etc.)

b. the functions of automatic report printing are as follows: timing and call printing of operating parameters, timing printing of electricity report, statistical report form of voltage qualification rate, load monitoring, statistical report form of average, peak and valley electricity, real-time and call printing of event records, call printing of equipment management document, printing of main wiring diagram, load curve, voltage curve, etc., printing of protection setting value and soft pressing plate position, The calling printing of the action time and action times of the tap changer adjustment of the main transformer, and the calling printing of the action time and action times of each protection and switch

c. the circuit breaker is monitored. Its position status is monitored by light, and the position status can be displayed on the CRT. When the control circuit is faulty and the AC circuit is disconnected, it can send a message in time

d. the selection of local control and remote control of devices and equipment can also be implemented in the monitoring system, and perfect encryption measures are set in the modification process of protection setting value

e. realize the synchronous display of the gear and actual state of the main transformer tap on the CRT

f. the wiring diagram of the station power system and the actual state of the equipment are synchronously displayed on the CRT

g. it realizes the simulation display of the real-time state of each power equipment, and can operate accordingly with the simulation diagram

3 telecontrol signal part

the telecontrol part adopts the communication mode to realize the remote transmission of telemetry, remote signaling, remote control, remote adjustment and electrical measurement, the remote monitoring and modification of protection setting value, and the acceptance and implementation of remote adjustment, remote control and other functions

3.1 remote measurement

remote measurement includes: active power, reactive power, current, voltage, power factor, oil temperature of main transformer at low voltage side of main transformer; 10kV line current, active power and reactive power; Three phase current and reactive power of 10kV capacitor circuit; 35kV, 10kV bus three-phase voltage, line voltage, 3uo (line voltage can be switched); Station transformer voltage and load current

3.2 telematics

signals that can be collected by the upper computer: various functional signals of the automatic protection device, the opening and closing signals of 35kv/10kv circuit breakers and voltage disconnectors at all levels (including the state of the low-voltage control switch of the transformer used), the overtemperature and overload signals of the main transformer, the light gas and heavy gas signals of the main transformer body, the detection of UPS AC power loss signals, the detection of 10kV outgoing circuit, capacitor circuit and 35kV switch control circuit disconnection signals, PT secondary circuit disconnection signal, main transformer gear detection signal, 35kV and 10kV grounding detection signal; 10kV capacitor circuit voltage loss, overvoltage, quick break, overcurrent, zero voltage signals, 35kV SF6 circuit breaker pressure and alarm, locking signals, etc

3.3 electric energy remote measurement

low to main transformer

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