The protection device, to put it bluntly, is a bit like a fuse, where there is a short circuit, quickly burn the fuse first, the circuit will be broken, those valuable electrical equipment will not suffer, and there will be no fire at home. It's just that the protection device will not really burn out, its role is to command the switch to trip, the same as the fuse to burn out.

Implement to the line protection, its core meaning is naturally to protect the "wire", "cable", "line switch" and other equipment of the large "fuse", in the critical case of line failure to cut off the switch, but also indirectly ensure the safety of the surrounding lines, transformers, without this thing, the speed of your power grid can not catch up with the speed of "bombing" the power grid.

There are many factors that "bomb" the power grid, perhaps lightning strikes, counter-attack mines, wind-around mines, serial mines, or wind deviations, icing, and wildfires...... As well as birds that don't have long eyes, kites with short lines, old farmers who steal wires, and so on......

Once these terrible accidents appear, lightning protection facilities, bird repellent devices, windproof and anti-ice design and national laws have not been able to prevent the above deposits, transmission lines will appear the most terrible disconnection, short circuit faults, overvoltage, overcurrent and other abnormal phenomena, the instantaneous current will be swept like a tsunami, and finally it is to highlight a "bomb" word, you are not finished with a blow-up, the chain accident is the most terrible, one after another like dominoes to blow down.

Therefore, it is absolutely necessary to configure relay protection devices on transmission lines, and the reason why line protection is simpler than generator and transformer protection is that the parameters and calculation principles that he needs to observe are relatively simple.

Suppose A, B, C three points are equipped with switches and relay protection, between which is the transmission line, at this time, due to various reasons, a ground fault occurs somewhere, how to capture where the fault point is, and then automatically cut off the relevant switch?

This is power transmission. So naturally we have to look at voltage and current, and in order to be more scientific and simplified, we choose to look only at their ratios. That is, the voltage divided by the current, which is the u/i. This gives a numerical value called impedance, z.

What a classic formula this is, a guy named Ohm was the first to discover this formula, so there is a simple formula r=u/i that everyone likes in middle school textbooks, which means that in a circuit, voltage divided by current can get resistance. Then the main use of line protection is actually this formula, the impedance is actually the resistance, and the line protection guò constantly captures the "resistance". to determine if something bad has happened to this section of the line.

Once the "resistance" deviates from the standard value large enough, the line protection can be sure that we have something wrong here, so it will issue a trip order, break me off, and protect everyone.

Back to A, B, C between the three points, assuming that the accident point is between A and B, then because the three points are close to each other, the protection device of A, B, C three points will capture this change, the protection device of point A and B point is judged to be a fault in the area after calculation and analysis, and at the same time the trip instruction is issued within tens of milliseconds; It judged that it was a fault outside the area and did not belong to its own business, so it did not move. Such. The switches at point A and point B are jumped, and point C is protected from damage and continues to operate in a closed state.

There may be a place here that is difficult to understand, the line between A and B is broken, is there any use for you to still close point C?

It is necessary to know that the power grid grid, that is a web, extending in all directions like a spider web, and the lines are intricate. The electricity from point A needs to be transmitted to point C, and there is more than one channel for B. The AB line where the accident occurred was cut off, and the power will continue to be transmitted from other lines. It ensures the safety and stability of the entire power grid.

Therefore, the core value is the impedance of the line protection, the principle is relatively simple, in the most basic situation, you only need to calculate the impedance, and then according to the status of this value to judge whether it is an accident in the area.

Of course, this is only relative, in the actual working conditions, it is necessary to capture a series of numbers such as frequency and direction, divide them into hundreds of situations and calculate them separately, and finally calculate the most scientific action effect.

This is what the software system has to do, and the hope of the science and engineering man and the program ape to make a fortune lies.

And now, Chang Jiang proposed a series of simplifications, is in the face of this software system, in the long years of development, microcomputer protection is like the operating system more and more high-end, from win95, to XP and 7, more and more functions emerge, must be intelligent measurement of accident distance, communication network and other protection interoperability analysis and so on. Figuratively speaking,Zhang Yifu's plan may be win95,But now it's still the DOS era,You only need to make it enough to be a big brother,Directly out of win95Not only you are tired,People are tired,It's also difficult for you to surpass yourself。

"These simplifications are fine, but if they leave room for expansion, it is better to stay. Zhang Yifu listened to Chang Jiang's introduction, glanced at the new solution and said, "For example, in the area of network communication, the software part can be left out first, but the port should be set aside to ensure that we can upgrade the new functions through the update of the guò version." ”

"Hmm......" Chang Jiang frowned, "but in this way, in terms of the physical port and industrial design of microcomputer protection, ......"

"Make space. Zhang Yifu nodded affirmatively, "The development of automation and communication is faster than we imagined. ”

"Alright then, we'll refine the design for this part. Chang Jiang sighed, didn't argue about this matter first, and instead looked at the bare metal not far away, although he didn't want to admit it in his heart, Zhang Yifu was correct most of the time, and it was so correct that it was incomprehensible," In our recent debugging, we have tried to manually input various parameter reactions, observe the action, the effect is scary, the algorithm and model you gave, I don't understand many places, just write it down, I thought that the debugging needs to be constantly modified and redone, but I didn't expect that the stability is almost a full score, and occasionally there are problems, which are also mistakes in our programming, and have nothing to do with the principle of the algorithm. ”

"Winning the ......" Zhang Yifu didn't know how to answer, he didn't want to ask the details of the algorithm, he couldn't explain it if he died.

"Moreover, although these things are only less than 30% of the design scheme, Mr. Chen and I firmly believe that they are absolutely at the international first-class level, and the breakthrough in algorithm principles surpasses many domestic universities. Chang Jiang stared at the bare metal, "We must protect that core, fully encrypt it, and avoid decompilation." ”

Xiang Xiaofei patted her head: "How do I feel like I have to spend money again......"

Compared with the R&D expenses, the money spent on security is actually only a drop in the bucket, which is equivalent to the difference between the money spent on buying a set and the opening fee.

"That's all for later. Chen Yanrui felt that his energy was a little exhausted, and reminded him appropriately, "Let's start the experiment first, this experiment will take at least a few weeks, press the switch first, and then discuss the details." ”

"Hmm. Zhang Yifu affirmed.

"It's all ready, Mr. Chen. Chang Jiang also nodded at Chen Yanrui.

Chen Yanrui's hand was raised and touched the button of the test instrument, but he didn't press it, he knew that the meaning of this act was not just to press a button, but also a very important ritual.

"Shaw, come on. Chen Yanrui hesitated.

"Don't, you come, you come. ”

"I think so, let's do it together. Chang Jiang smiled, "Come, let's put a few hands on the back of Mr. Chen's hand." ”

With that, he was the first to take it.

Chang Jiang is quite good at doing it!

Zhang Yifu thought so and also took it.

Then there is Xiang Xiaofei.

Chen Yanrui has lived for so long, and he has never experienced this feeling, three young hands, hands with different temperatures, are intertwined with him, an old guy, and the pulsation of blood is transmitted through the skin, along Chen Yanrui's already somewhat hardened blood vessels, to the somewhat tired heart.

Knock Knock...... Knock Knock......

The heartbeats of the four people intertwine and merge.

Chen Yanrui felt, listened, and witnessed it himself, he suppressed his excitement and expectation, and finally pressed the button with a little fear.

Digital simulation simulation has officially begun!

At the same time, the domestic independent research and development of microcomputer protection, half a leg has entered the threshold!

It was supposed to be an exhilarating moment like the Apollo moon landing, but at the test site, there was no physical substance, only the sound of a bunch of fans.

Everyone gradually let go, and their eyes were fixed on the numbers on the electronic screen of the test instrument.

Not to mention Xiang Xiaofei, Zhang Yifu is a little incomprehensible.

Chang Jiang stared at it and explained to everyone: "This simulation environment, I and Mr. Chen have set it before, for the convenience of the test, the accident frequency is set to 'high incidence', and the time parameter is also set to 'extremely fast', approximately, 10 minutes here is about equivalent to the change of a high-accident transmission line for half a year." ”

"That's right. Zhang Yifu said with a smile, "Time synchronization, accident rate synchronization, pure simulation, we may not have a few changes if we guard the computer for half a year." ”

"Well, now this setting, according to the description of the manual, there are about 5-10 times of sensitive number jù changes in an hour, of which 70% are non-accidents, or disturbances caused by other line accidents, and only 30% are local line accidents that need to output a trip signal. Chang Jiang stared at the screen seriously, "We have to ensure that the 70% of the situation does not send a trip signal, if the calculation and judgment error to send a trip instruction, it is a mistake; at the same time, we must also ensure that the 30% should jump and jump, if not jump is a refusal." These numbers are then combined to calculate the misflight rate and rejection rate to derive 'reliability'. ”

"After all, everything we do is for reliability, and of course, speediness, selectivity, and sensitivity. Chen Yanrui was also nervous after being slightly excited, "Only when these four sexes meet the standards can follow-up tests and trial runs be carried out." ”

"How much should it be?" asked Xiang Xiaofei. (To be continued)