CN2078942U - Microcomputer-type differential relay - Google Patents

Abstract

The utility model relates to a microcomputer type differential relay for protecting power transformers, comprising a combined current and potential transformer, a ten-path low pass filter and the sampling holder thereof, an analogue/digital converter and a microcomputer processor. The microcomputer type differential relay is characterized in that the interior of the memory circuit of the microcomputer processor adopts an electrically erasable ROM to store setting values and is connected with a return circuit for rewriting the setting values, which makes the setting values able to be rewritten optionally at any time without any influence to the content of other memories. The utility model which can remove faults in 15 milliseconds has high sensitive rate, reliable performance and easy use, able to meet the requirements of safe operation in power systems.

Description

Microcomputer type sudden change amount differential relay

The utility model relates to a kind of microcomputer type differential relay that is used to protect power transformer.

Transformer differential relay had for four generations; (1) old-fashioned electromagnetic type differential relay; (2) old-fashioned rectification type differential relay; (3) transistor-type differential relay; (4) integrated circuit type differential relay.These four kinds of relay common features are that to adopt the simulation electric weight be that the actual value of the magnitude of current and voltage is moved comparison; preceding two kinds very outmoded; responsiveness is very slow; sensitivity is also very low; can not adapt to the requirement of high-pressure system tranformer protection, though back two kinds of existing obviously raisings on performance are still disliking not enough aspect responsiveness and the sensitivity; especially to superhigh pressure, jumbo power transformer, wish that the differential relay performance of protecting it not to be damaged is more superior better.In addition; domestic also have a kind of PC relay that the power transformer circuit is protected; the setting value of its inside is rewritten the loop and is all adopted read-only memory; though can preserve data well; but it is pretty troublesome to rewrite setting value; the ultraviolet equipment that needs configure dedicated to add; could rewrite after all wiping with ultraviolet ray; and execute-in-place; generally can't grasp, it is also shorter to rewrite the life-span, rewrites at most hundreds of times; and need often to adjust according to load variations by the current/voltage setting value of transformer or circuit, this is the insurmountable problem of this relay.

The purpose of this utility model is exactly in order to overcome above-mentioned shortcoming, and a kind of the 5th generation microcomputer type sudden change amount differential relay is provided, and its responsiveness and action sensitivity have all improved an order of magnitude, and setting value can be rewritten arbitrarily at any time.

Technical solution of the present utility model is as shown in the figure:

Fig. 1 is a theory diagram of the present utility model;

Fig. 2 is the utility model computer processor electrical schematic diagram;

Fig. 3 is the utility model low pass filter electrical schematic diagram.

Such as Fig. 1,2, the utility model is by current transformer B₁、B ₂、B ₃, voltage transformer B₄, auxiliary reactance transformer KH₁～KH ₇, auxiliary potential transformer YH₁～YH ₃, balancing, the anti-shock resistance circuit A that shoves₁～A ₁₀, No. ten low pass filter LF₁～LF ₁₀And sampling hold circuit SH₁～SH ₁₀, A/D converter A/O, computer processor and photoelectricity input, output control circuit I/O-1, I/O-2 form, and wherein computer processor is by frequency generator and frequency divider U₉、U ₁₄, central processor CPU (U₅), buffer circuit U₇、 U ₈、U ₂₂, logic control circuit U₁₃, interrupt control circuit U₂₁, serial interface circuit U₁₇, parallel interface U₂₆、U ₃₆, clock circuit U₄, the baud rate circuit U₁₈, local logic control circuit U₂₈Form with main memory circuit, it is characterized in that the main memory circuit of computer processor is by electrically erasable read-only memory U₃₄，U ₃₅, random access memory U₃₂、U ₃₃With read-only storage U₃₀、U ₃₁Consist of electrically erasable read-only memory U₃₄Be even number sheet, U₃₅Be odd number sheet, U₃₄The data/address bus input be connected to the D of data/address bus₀～D ₇，U ₃₅The data/address bus input be connected to the D of data/address bus₈～D ₁₅，U ₃₄、U ₃₅The address bus input all be connected to the A of address bus₁～A ₁₃On, random access memory U₃₂Be even number sheet, U₃₃Be the odd number sheet, read-only storage U₃₀Be even number sheet, U₃₁Be odd number sheet, random access memory U₃₂、U ₃₃With read-only storage U₃₀、U ₃₁Data/address bus input, address bus input and data/address bus, connected mode and the read-only storage U of electric erasable of address bus₃₄、U ₃₅Connected mode identical, read-only storage U₃₀、U ₃₁Gating end CE connect respectively and not gate U₂₃、U ₂₄Output, when with not gate U₁₂Input A₁₆～A ₁₉With M I_D

When entirely being high level, U₁₂Output low level, then U₂₃、U ₂₄Respectively by the address bus AD and the central processor CPU (U that import₅) the control signal BHE control sent, random access memory U₃₂、U ₃₃With electrically erasable read-only memory U₃₄、U ₃₅Gating end CE respectively corresponding and local logic control circuit U₂₈Pulse signal output end O0a, O0b, Ota, O1b connect electrically erasable read-only memory U₃₄、U ₃₅The end WE that writes connect normally closed contact K by linked switch K₁Connect the positive pole of capacitor C, the minus earth of C, simultaneously, U₃₄、U ₃₅Write the also normally opened contact K by linked switch K of end WE₂Be connected electrically erasable read-only memory U with the write signal output WE of central processor CPU₃₄、U ₃₅Control end 1 pass through respectively resistance R₁₈、R ₁₉Meet+the 5V power supply U₃₄、U ₃₅Control end 1 also connect respectively and door U₂₉Input 4,5, with door U₂₉Output 6 and with door U '₂₉Input 2 connect U '₂₉Input 1 connect and not gate U₁₉Output 12, with not gate U₁₉, frequency divider U₁₄With with not gate U₁₅Form the stand-by period circuit for generating, it is given and door U '₂₉1 input scouring time of inserting about 500 μ s, U '₂₉Output 3 be connected to oscillator U in frequency generator and the frequency divider₉Preparation state end ROY₁，U ₉Preparation state end REAOY be connected preparation state end REAOY with central processor CPU and connect, make CPU be in wait state at 500 μ s in the insertion time, make electrically erasable read-only memory U₃₄，U ₃₅Can clean at this moment and fall old memory content; The normal opened contact K of linked switch K₂At electrically erasable read-only memory U₃₄、U ₃₅Be in off-state when not writing new content, K₂(this moment normally closed contact K during disconnection₁Connection) makes U₃₄、U ₃₅The end WE that writes connect a unsettled line, capacitor C be used for preventing the electromagnetism on the unsettled line do anti-, to guarantee U₃₄，U ₃₅In content can stably preserve, as electrically erasable read-only memory U₃₄、U ₃₅In content need rewrite new content the time, the normally closed contact K of linked switch K₁Disconnect normal opened contact K₂Connect, make the write signal WR of central processing unit C PU can enter smoothly U₃₄、U ₃₅Write the end WE, this moment capacitor C be in disconnected Open position has been avoided the decay to CPU high frequency write signal WR.

As Fig. 1, when the utility model uses, from the both sides three-phase current access current transformer B of two circle power transformer T ₁, B ₂, the on high-tension side central point electric current of two circle power transformer T meets current transformer B ₃, power transformer T high-voltage side bus three-phase electricity crimping voltage transformer B ₄, having seven road electric currents and three road voltages, seven road current signals insert auxiliary reactance transformer KH ₁～KH ₇, three road voltage signals insert auxiliary potential transformer YH ₁～YH ₃, during power transformer T operation working properly, its low-pressure side electric current

(flow into power transformer Electric current) should with its high voltage side current

(flowing out the electric current of power transformer T) size is identical, and according to B among Fig. 1 ₁, B ₂The polarity connection, its direction is also identical, sets differential operating current in the utility model ${\stackrel{\·}{I}}_D={\stackrel{\·}{I}}_H-{\stackrel{\·}{I}}_L,$ Stalling current $\stackrel{\·}{I}z={\stackrel{\·}{I}}_H+{\stackrel{\·}{I}}_L,$ When then power transformer T normally moves, differential operating current ${\stackrel{\·}{I}}_D={\stackrel{\·}{I}}_H-{\stackrel{\·}{I}}_L=0,$ Stalling current ${\stackrel{\·}{I}}_Z={\stackrel{\·}{I}}_H+{\stackrel{\·}{I}}_L=2{\stackrel{\·}{I}}_H,$ Very big, so the utility model is not carried out action.The power supply of generator F passes through power transformer T to the load normal power supply; When power transformer T inside is short-circuited fault, because of the short dot current potential reduces, so the electric current of power transformer T high and low pressure both sides

All flow to power transformer T, at this moment, differential operating current

Very big, and stalling current ${\stackrel{\·}{I}}_Z={\stackrel{\·}{I}}_H-{\stackrel{\·}{I}}_L\≈0,$ So the utility model action is serially connected in two circle power transformer T low-pressure sides and on high-tension side circuit breaker D through the trip signal excision takes place after the MICROCOMPUTER PROCESSING ₁, D ₂, protection power transformer T is unlikely to scaling loss, and makes the stabilization of power grids to the load power supply, and the concrete course of work of the utility model is that seven road electric currents and three road voltage signals are respectively through auxiliary reactance transformer KH ₁～KH ₇With auxiliary potential transformer YH ₁～YH ₃After the conversion, send into balancing, the anti-shock resistance circuit A that shoves ₁～A ₁₀Carry out preliminary treatment, No. ten low pass filter LF are sent in its output respectively ₁～LF ₁₀The filtering high order harmonic component.No. ten low pass filter circuits are all identical, its circuit as shown in Figure 3, it is by resistance R _3-3, R _3-4, potentiometer W _3-2, W _3-3, capacitor C _3-1, C _3-2, C _3-3With amplifier U _3-1Form, balancing, anti-ly shove the shock resistance circuit (by R _3-1, R _3-2, W _3-1, D _3-1～D _3-4, C _3-6Composition) output connecting resistance R _3-3With potentiometer W _3-2Serial connection branch road one end, this serial connection branch road other end with by W _3-3, R _3-4, C _3-2The input of the integrating circuit of forming connects, W _3-3, R _3-4, C _3-2The output termination amplifier U of the integrating circuit of forming _3-1In-phase input end 3, U _3-1Output 6 directly and U _3-1Inverting input 2 connect, and pass through capacitor C _3-1Be connected to potentiometer W _3-2, W _3-3Mid point, form positive feedback loop, during low pass filter work, R _3-3, W _3-2And C _3-1Form first order integral filter circuit, the output of first order integral filter circuit meets second level integrating circuit (W again _3-3, R _3-4, C _3-2) input, this two-stage integration filter circuit is tentatively with the high order harmonic component filtering, again through the amplifier U of high-amplification-factor _3-1Positive feedback effect, just strengthened their filter effect greatly, make the whole filterings of high order harmonic component that 300Hz is above, the sampling holder U of next stage is just sent in the output of low pass filter _3-2, U _3-2Have the very high linearity and stability, the energy inhibit signal is constant, guarantees A/D conversion accuracy.As Fig. 1, No. ten low pass filter LF ₁～LF ₁₀Output send ten road sampling holder SH respectively ₁～SH ₁₀, SH ₁～SH ₁₀According to by parallel interface U ₂₆The 12 point sampling speed synchronized samplings of ripple weekly sent of PA mouth (Fig. 2), send into modulus converter A/D in order through variable connector MK and carry out analog-to-digital conversion, it is exported 12 position digital signals and carries out calculation process to computer processor.As Fig. 2, the computer processor course of work is that 12 position digital signals of being sent here by A/D deposit random asccess memory U in by data/address bus ₃₂, U ₃₃, central processor CPU is according to being solidificated in read-only memory U in advance ₃₀, U ₃₁Interior software program will deposit U in ₃₂, U ₃₃Data carry out calculation process, arithmetic speed is by the oscillator U in frequency generator and the frequency divider ₉Control, U ₉Producing 5MHz is the clock cycle of 200ns, and central processor CPU is just according to this clock cycle high speed operation, and produces differential operating current I by leaf-size class transformation of variables method in winning _DStalling current I _ZAmplitude, I _DAmplitude with pre-deposit electrically erasable read-only memory U ₃₄, U ₃₅In differential operating current standard value (being setting value) Is compare, if I _D＞I _S, and I _D＞I _Z, then computer processor is to parallel interface U ₂₆, U ₃₆The PB mouth send the tripping operation password, the photoelectric yield device I/O-2 by photoelectricity input, output control circuit sends high level, makes circuit breaker D ₁, D ₂Tripping operation, and send alarm signal, computer processor also passes through U ₂₆, U ₃₆The PC mouth start printer, the record relevant data is convenient to the operations staff and is checked analyzing failure cause; If I _D＜I _S, or I _D＜I _Z, show that power transformer T is in normal operating condition, then computer processor is not to parallel interface U ₂₆, U ₃₆Send the execution signal, continue to handle new data, so circulation constantly repeats work.Interrupt control circuit U among Fig. 2 ₂₁Be used for the multiple different function of the utility model is according to priority carried out Interrupt Process (multiple difference in functionality of the present utility model includes protection operational mode, printing operational mode, automatic detection mode and adjusts definite value working method etc.) by its important level.Serial interface circuit U ₁₇Be to work when linking to each other with terminal (CRT) at the utility model, it is according to Baud rate generator U ₁₈The work of baud rate of sending and terminal (CRT) coupling, be mainly used to as on-the-spot with terminal (CRT) to the utility model debug, Peripheral Interface when checking.Clock circuit U ₄Be the programmable clock signal generator, main effect is to produce year, month, day, hour, min, the real-time clock of second, when this clock was accurately walked before 2000 automatically, influences the leap month of not being subjected to the leap year, and can print year, month, day, hour, min, second time.Baud rate generator U ₁₈With frequency divider U ₃₈Produce the 600Hz frequency by the U in the parallel interface ₂₆The PA mouth give sampling holder SH of the present utility model ₁～SH ₁₀The sampling reference frequency of 12 in ripple is provided weekly.Logic control circuit U ₁₃Produce control signal, control each circuit working, local logic control circuit U ₂₈Produce gating signal, the work of control main memory circuit.In Fig. 1, the photoelectricity loader I/O-1 in the photoelectricity input/output control circuit is used to provide three road contact control signals, can make the utility model meet desired concrete operational mode according to the specific requirement at scene.Setting value is rewritten the loop by electrically erasable read-only memory U among keypad and Fig. 2 ₃₄, U ₃₅Write end linked switch K that WE connected and capacitor C and form, when need are rewritten, the normal opened contact K of the K that closes ₂(this moment normally closed contact K ₁Disconnect), according to being solidificated in read-only memory U ₃₀, U ₃₁Interior setting value monitoring program operation keypad can arbitrarily be rewritten U at any time ₃₄, U ₃₅Interior setting value content, and do not influence other content.

The utility model be the 5th generation the latest model relay, it adopts sudden change amount current differential principle, realize the comparison of differential operating current and stalling current and setting value with microcomputer, arithmetic speed is very high, can excise fault in 15/1000ths seconds, and the existing relay of remolding sensitivity exceeds an order of magnitude, can reduce the degree of injury of power transformer to greatest extent, the utility model is a domestic initiation, has filled up the blank of China, is in the first place in the world.The utility model in computer processor owing to adopt electrically erasable read-only memory, make that the rewriting setting value is very convenient, can arbitrarily rewrite any one setting value according to field requirement at any time, rewriting number of times can reach hundreds thousand of times, useful life, big leap ahead and did not influence other memory content, and need not the ultraviolet optional equipment that special use adds, at the scene, the operation operations staff grasps easily.The utility model is owing to adopt second order positive feedback active low-pass filter, its superior performance, guaranteed the high-quality processing of sampling circuit to the input analog signal, be provided with balancing, the anti-shock resistance circuit that shoves at signal input port, external interface adopts the generating coupler to isolate, and does anti-performance so have good anti-electromagnetism.The utility model keypad adopts the man-machine conversation mode, and on-the-spot use is directly perceived, convenient, grasps easily.The utility model advanced technology, stable performance is good, can satisfy the needs of power system security reliability service.

Claims (3)

1, a kind of microcomputer type sudden change amount differential relay, it is by current transformer B ₁, B ₂, B ₃, voltage transformer B ₄, auxiliary reactance transformer KH ₁～KH ₇, auxiliary potential transformer YH ₁～YH ₃, balancing, the anti-shock resistance circuit A that shoves ₁～A ₁₀, No. ten low pass filter LF ₁～LF ₁₀And sampling hold circuit SH ₁～SH ₁₀, modulus converter A/D, computer processor and photoelectricity input/output control circuit I/O-1, I/O-2 form, and wherein computer processor is by frequency generator and frequency divider U ₉, U ₁₄, central processor CPU (U ₅), buffer circuit U ₇, U ₈, U ₂₂, logic control circuit U ₁₃, interrupt control circuit U ₂₁, serial interface circuit U ₁₇, parallel interface U ₂₆, U ₃₆, clock circuit U ₄₁The baud rate circuit U ₁₈, local logic control circuit U ₂₈With main memory circuit U ₃₀～U ₃₅Form, the main memory circuit that it is characterized in that computer processor is by electrically erasable read-only memory ₃₄, U ₃₅, random asccess memory U ₃₂, U ₃₃With read-only memory U ₃₀, U ₃₁Constitute electrically erasable read-only memory U ₃₄Be even number sheet, U ₃₅Be odd number sheet, U ₃₄The data/address bus input be connected to the D of data/address bus ₀～D ₇, U ₃₅The data/address bus input be connected to the D of data/address bus ₈～D ₁₅, U ₃₄, U ₃₅The address bus input all be connected to the A of address bus ₁～A ₁₃On, random asccess memory U ₃₂Be even number sheet, U ₃₃Be the odd number sheet, read-only memory U ₃₀Be even number sheet, U ₃₁Be odd number sheet, U ₃₂, U ₃₃And U ₃₀, U ₃₁Data/address bus input, address bus input and data/address bus, the connected mode and the U of address bus ₃₄, U ₃₅Connected mode identical, U ₃₀, U ₃₁Gating end CE meet NAND gate U respectively ₂₃, U ₂₄Output, U ₂₃, U ₂₄The control signal BHE control sent by address bus and central processor CPU of input, U ₃₂, U ₃₃And U ₃₄, U ₃₅Gating end CE respectively corresponding with local logic control circuit U ₂₈Pulse signal output end O0a, O0b, O1a, O1b connect electrically erasable read-only memory U ₃₄, U ₃₅The end WE that writes connect normally closed contact K by linked switch K ₁Connect the positive pole of capacitor C, the minus earth of C, simultaneously, U ₃₄, U ₃₅Write the also normal opened contact K by linked switch K of end WE ₂Be connected U with the write signal output WR of central processor CPU ₃₄, U ₃₅Control end 1 pass through resistance R respectively ₁₈, R ₁₉Meet+the 5V power supply U ₃₄, U ₃₅Control end 1 also connect respectively with the door U ₂₉Input 4,5, with door U ₂₉Output 6 and with door U ' ₂₉Input 2 connect U ' ₂₉Input 1 meet NAND gate U ₁₉Output 12, NAND gate U ₁₉, frequency divider U ₁₄With NAND gate U ₁₅Form stand-by period generation circuit, it is given and door U ' ₂₉1 input scouring time of inserting about 500 μ s, U ' ₂₉Output 3 be connected to oscillator U in frequency generator and the frequency divider ₉Standby condition end RDY1, U ₉Standby condition end READY and the standby condition end READY of central processor CPU be connected.

2, by the described microcomputer type real variable of claim 1 differential relay, it is characterized in that low pass filter is by resistance R _3-3, R _3-4, potentiometer W _3-2, W _3-3, capacitor C _3-1, C _3-2, C _3-3With amplifier U _3-1Form the output connecting resistance R of balancing, the anti-shock resistance circuit that shoves _3-3With potentiometer W _3-2An end of serial connection branch road, this serial connection branch road other end with by W _3-3, R _3-4, C _3-2The input of the integrating circuit of forming connects, integrating circuit W _3-3, R _3-4, C _3-2Output termination amplifier U _3-1In-phase input end 3, U _3-1Output 6 directly and U _3-1Inverting input 2 connect, and pass through capacitor C _3-1Be connected to potentiometer W _3-2, W _3-3Mid point, form positive feedback loop.

3, by the described microcomputer type sudden change of claim 1 amount differential relay, it is characterized in that current transformer B ₁, B ₂Connect the three-phase current end of two circle power transformer T both sides, current transformer B ₃Connect two circle power transformer T high-pressure sides central point current terminal, voltage transformer B ₄Connect two circle power transformer T high-voltage side bus three-phase electricity pressure sides; Low-pressure side, two ends, high-pressure side at two circle power transformer T respectively are connected in series a circuit breaker D ₁, D ₂

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