CN1084537C - Microcomputer automatic identifying method for bus running manner - Google Patents

Abstract

The invention relates to a microcomputer automatic identification method for the operation mode of a bus in a power system. In the present invention, the microcomputer regularly reads the opening and closing states of the auxiliary contacts of the isolating switches of the connecting elements on the bus, and sets the microcomputer to read "1" if the auxiliary contacts are closed, and "0" if the auxiliary contacts are disconnected. ", the microcomputer stores the read content bit by bit as the operation mode word of the bus, and then uses Kirchhoff's law to calculate whether the current difference of each component connected to the bus is zero, if the current difference is zero, the microcomputer stores the read-in mode word and confirms it as the current bus operation mode word, if the current difference is not zero, the microcomputer inverts the read mode word bit by bit, and recalculates each time Inversely, the bus current drop of the way character is obtained. Until the situation that the small difference of the bus current is zero is found, the bus operation mode word after the inversion is confirmed as the current operation mode word and stored. The invention overcomes the original error caused by only relying on reading the state of the auxiliary contact, and can accurately track the operation of the busbar.

Description

A Microcomputer Automatic Recognition Method of Bus Running Mode

The invention relates to an identification method of a bus running mode, in particular to an automatic identification method using a microcomputer.

Among the various wirings of the power system bus, the double bus is the most complicated. The connecting elements on the bus need to switch between the two buses frequently according to the operation requirements, which requires the bus protection device to be able to automatically track the switching operation of a system. The busbar protection of the current system operation adopts the auxiliary contact of the isolation knife switch, starts the intermediate relay, and uses the contact of the intermediate relay to switch the current and the outlet circuit of the busbar protection. This method has the following shortcomings: First, the isolation that needs to be introduced The switch has many auxiliary contacts and the wiring is complicated. At least four pairs of auxiliary contacts (two normally open and two normally closed) need to be introduced into each connecting element. Secondly, the system is more complicated, and each component needs a lot of intermediate relays to complete the switching of current and outlet, especially for bypass and bus tie or bus and bypass wiring, which reduces the reliability of the whole protection. Again, the requirements for the auxiliary contact of the isolation switch are relatively high. Due to the contact problem of the auxiliary contact, the state of the auxiliary contact cannot truly reflect the operation of the primary system. The busbar protection can only be used to monitor the position of the auxiliary contact. Logic time-delay blocking the whole set of protection. In addition, the debugging and maintenance workload of the product is relatively large. With the development of computer technology, the process of relay protection microcomputerization is further accelerated, and the system's demand for microcomputer-based busbar protection is increasing. However, the conventional method of identifying busbar operation mode is obviously not suitable for microcomputer-based busbar protection devices.

The purpose of the present invention is to provide a method capable of automatically identifying the operation mode of the busbar, so as to meet the needs of the busbar protection device based on a microcomputer.

In order to achieve the above object, the technical solution adopted in the present invention is: a microcomputer automatic identification method of a bus operation mode, the method adopts the following steps:

(1) The microcomputer regularly reads the opening and closing states of the auxiliary contacts of the isolating switches of the connecting elements on the bus, and sets that if the auxiliary contacts are closed, the microcomputer reads "1", and if the auxiliary contacts are disconnected, the microcomputer reads "1". "0";

(2) The microcomputer stores the read content bit by bit as the operation mode word of the bus;

(3) Use Kirchhoff's law to calculate the current minimum difference of each component connected to the bus by using one-phase current;

(4) If the current difference is "0", the microcomputer stores the operation mode word of the bus and confirms it as the current operation mode word;

(5) If the current difference is not "0", the microcomputer inverts the original operation mode word by bit one by one, and recalculates the current difference until it finds that the bus current difference is "0", that is, the The operation mode word of the bus bar after the second inversion is confirmed as the current operation mode word and stored.

Because the present invention utilizes the microcomputer to regularly read the states of the auxiliary contacts of the isolating switches of the connection elements on the bus, and calculates the current small difference, if the small difference is 0, the states of the auxiliary contacts are confirmed as the operation mode word of the bus in order. ; If the calculated small difference is not 0, use the computer with strong computing power to invert the original operation mode bit by bit and recalculate the current small difference until the current small difference is found to be 0 to confirm The new operation mode word, at the same time sends out the unreliable signal of the auxiliary contact of the isolation switch, which is convenient for the operation personnel to deal with. Therefore, compared with the conventional method for identifying the operation mode of the busbar, with the identification method provided by the present invention, only two pairs of auxiliary contacts need to be introduced into each connecting element, which reduces the dependence on the auxiliary contacts of the isolating switch and simplifies The system is improved, the reliability is improved, and the maintenance workload of the system is reduced.

Further illustrate the present invention below in conjunction with accompanying drawing:

Figure 1 is a schematic diagram of the double-bus operation mode;

Figure 2 is a schematic diagram of the auxiliary contact reading circuit.

Taking the double busbar system shown in Figure 1 as an example, busbar I and busbar II are connected to L1, L2, L3 and L4 through G11, G12, G13, G14 and G21, G22, G23, G24 respectively. They are connected through bus tie switch G of bus tie L. Assuming that the switch G and the isolating switches G21, G12, G23, and G14 are in the closed state, and the isolating switches G11, G22, G13, and G24 are in the open state, the microcomputer reads each isolating switch through the auxiliary contact reading circuit shown in Figure 2 The state of a normally open auxiliary contact, then the opening and closing states of the auxiliary contacts of G11, G21, G12, G22, G13, G23, G14, G24, and G read by the microcomputer are "0", "1", "1", "0", "0", "1", "1", "0", "1", that is to say, the five isolating switches G11, G12, G13, G14, G connected to the I mother The opening and closing states of the auxiliary contacts are 0, 1, 0, 1, and 1 respectively. Based on this, the operation mode word of the letter I can be obtained as the five-digit operation mode word 01011. Similarly, the operation mode word of the letter II can be obtained as 10101. That is to say, there are three elements L2, L4, and G running on the I mother, and three elements L1, L3, and L on the II mother. If the opening and closing functions of the auxiliary contacts of the above-mentioned isolation switches are reliable and the contact is good, then the opening and closing states of the auxiliary contacts of the isolation switches read by the microcomputer can correspond to and correctly reflect the opening and closing of the main contacts of the isolation switches. Closed state, that is, the switching operation that can truly reflect the operation mode of bus I and bus II. However, if the auxiliary contact of one of the above-mentioned isolating switches is unreliable in opening and closing and in poor contact, the bus operation mode word read by the microcomputer will be wrong, so that the system cannot accurately track the switching operation and operating status of the system. , affecting the normal operation of the system, for example, in the case of normal operation of the double busbar and its connecting components in Figure 1, if the auxiliary contact action of the isolation switch G11 is unreliable or the contact is poor, then the operation mode of I under normal conditions is " 01011" will therefore be regularly read as "11011" by the microcomputer, and the monitoring personnel mistakenly believe that the component L1 is also running on the I mother, resulting in tracking errors, which will bring many impacts on the monitoring and normal operation of the primary system.

In order to avoid the occurrence of the above-mentioned errors, the present invention introduces a current verification method, that is, the microcomputer regularly reads the opening and closing states of the auxiliary contacts of the isolating switches connected to the two busbars to form their respective operating mode characters. On the basis of , and then use Kirchhoff's law to introduce a phase current method to calculate whether the current flowing into and out of each bus is equal, that is, to calculate whether the current difference on each bus is "0", if the calculated If the small difference is zero, the mode read by the microcomputer at regular intervals is confirmed and stored. As shown in Figure 1, the operation mode word of letter I read by the microcomputer is 01011, and the operation mode word of letter II is 10101, and then adopt Introduce a phase current (such as A-phase current), the magnitude and direction of the current are shown in Figure 1, then the current difference of I mother is: ∑i _I =0×i ₁ +1×i ₂ +0×i ₃ + 1×(-i ₄ )+1×(-i ₀ )＝i ₂ +(-i ₄ )+(-i ₀ )＝i ₂ -i ₄ -i ₀ , the current difference of II mother is: ∑i _II =1×(-i ₁ )+0×i ₂ ×+1×(-i ₃ )+0×i ₄ +1×i ₀ =(-i ₁ )+(-i ₃ )+i ₀ . When the primary system works normally, and the auxiliary contacts of each isolating switch are reliable and in good contact, the result of the verification of the current introduced by the microcomputer will be Σi _I = 0, Σi _II = 0, so the microcomputer will read the aforementioned into The operation mode word is I letter: 01011, II letter 10101 is confirmed and stored as the current bus operation mode word.

As shown in Figure 1 and Figure 2, if the auxiliary contact of the isolating switch is unreliable or has poor contact, then the microcomputer will read the wrong bus operation mode word. Assuming that the above-mentioned various actual states in Fig. 1 remain unchanged, and the auxiliary contact of the G14 isolating switch of the I mother element L4 is in poor contact, the operation mode word of the I mother read by the microcomputer will become 01001 (while the actual operation The mode word should be 01011). The microcomputer then introduces a phase current to calculate the small difference of I mother, at this time ∑i _I =0×i ₁ +1×i ₂ +0×i ₃ +0×(-i ₄ )+1×(-i ₀ ) =-i ₂ -i ₀ ≠0, then the microcomputer thinks that the state of the auxiliary contact of the isolating switch is wrong, and then the microcomputer will reverse the read operation mode word 01001 bit by bit and Calculate the small difference of the I bus current after the inversion, and there are five cases of bit-by-bit inversion in the case of only five-bit mode words: 01001→11001, 01001→00001, 01001→01101, 01001→01011, 01001→01000, The microcomputer inverts once bit by bit, and uses the obtained imaginary bus operation mode word to recalculate the current difference of I bus. The current difference of the first three times of the computer is not zero, until the fourth result is found by bit by bit inversion. 01011 , the result that the current differential is zero can be calculated, and the microcomputer’s determination of the operation mode word of I bus stops here. In addition, the auxiliary contact of II bus has no knowledge, and the current sub-difference of II bus calculated by the microcomputer is also Be " 0 ", at this moment, microcomputer just replaces 01001 with operating mode word 01011 and is determined to be the current operating mode word of I mother and be stored, and the present operating mode word of II mother is confirmed and stored as 10101.

During the calculation process of the bit-by-bit inversion of the above-mentioned microcomputer, as long as the microcomputer finds that the current difference between the two busbars is zero, the search will be stopped, and the operation mode word obtained after this inversion will be confirmed and stored as the current operation. way word.

Claims (1)

1, a kind of microcomputer automatic identifying method of bus running manner is characterized in that this method adopts following steps:

(1) regularly read the folding condition of each Connection Element isolating switch auxiliary contact on the bus by microcomputer, and set as if the auxiliary contact closure, microcomputer is read as " 1 ", is read as " 0 " if auxiliary contact disconnect microcomputer;

(2) microcomputer stores operational mode word as bus by turn to the content that reads;

(3) utilize Kirchhoff's law to adopt a phase current to calculate the little difference of electric current that connects each element on the bus;

(4) if the little difference of electric current is " 0 ", microcomputer is stored the operational mode word of bus and is confirmed as present operational mode word;

(5) if the little difference of electric current is not " 0 ", microcomputer is to the negate one by one by turn of original operational mode word, and it is little poor to recomputate electric current, is the situation of " 0 " until searching the little difference of bus current, promptly present operational mode word is confirmed as in the operational mode word of the bus after this time negate and is stored.

Images