RU2247456C2 - Power equipment relay protection method - Google Patents

Abstract

FIELD: electrical and power engineering; protection of power transmission lines, generators, transformers, and the like.

SUBSTANCE: proposed method involves joint conversion of electrical quantities being measured and a priori data on power equipment into two-dimensional signals for actuating final group of relays; discrimination of separate locations on each two-dimensional signal plane; preparation of code arrays from location numbers of different planes; testing of protective gear on power equipment simulators in alternative conditions and determination of respective operation-failure codes which are deleted from code arrays; testing of protective gear on power equipment simulators in test conditions and determination of respective operation codes; saving of these codes in code array and deletion of remaining codes; assembly of groups of similar relays while duplicating each main relay by similar additional relay and assembly of additional groups of final relays. One relay out of each group of similar relays is included in each group of final relays. Assumed as operation regions are relays of respective code location on respective planes. Output signals of all relays of same additional final group are integrated by AND logic operation and output signals of all final groups, by OR operation whose result is added to output signal relay protective gear.

EFFECT: enhanced capability of short circuit detection.

6 cl, 3 dwg

Description

The invention relates to electrical engineering and the electric power industry, namely to relay protection, can be applied to protect various power facilities: power lines, generators, transformers and others.

Typically, relay protection devices use only part of the available information about the state of the monitored facility. For example, three currents and three voltages of different phases of a power line are measured. In the distance protection, three resistance relays are installed to control each of the three interphase channels, supplying one current and one voltage to the inputs of one relay. The relays operate independently of each other, using only the information that is included in their own input quantities. The remaining information by each individual relay is ignored, although it is used by other relays, but, of course, also in parts that are worn by each of them.

Known technical solution [1], according to which the relay receives as input values a larger number of measured currents and voltages. This is done for the sake of expanding the functionality of the relay, which acquires as a result the ability to recognize phase-to-phase faults in various phases. Over time, a class of such relays became known, which were called three-phase [2] or multiphase.

There are also known methods of combining information in order to increase the recognition ability of protection [3,4]. Their distinctive feature is that the measured electrical quantities are converted together with a priori information about the energy object into complex quantities. Joint transformation is implemented using the model of the energy object, the parameters of which are set taking into account a priori information. Complex quantities, such as complex resistance, each displayed on its own complex plane, are two-dimensional signals. Each of these signals, obtained by converting all available information about the state of the object, is fed to the input of one relay.

Considering all the relays as an executive group, their output signals are combined with the logical operation AND, the result of which is used as the output signal of the relay protection. Each two-dimensional signal is displayed on its own plane, where the response area of the corresponding relay is set. The response characteristics - the boundaries of the regions - are determined by checking the operation of the protection on the simulation models of the energy object in modes alternative to the controlled one, the recognition of which is the task of relay protection. The principal disadvantage of this method is that for each two-dimensional signal that carries part of the information about the state of the object, only one response characteristic is associated. Protection is triggered if all signals fall into their flat response areas. However, this triggering condition does not exhaust all the possibilities of recognizing emergency conditions of a power facility.

The aim of the invention is to increase the sensitivity of relay protection, understood as increasing its ability to recognize short circuits.

This goal is achieved by the fact that the known method of relay protection, in which some measures are taken to combine information about the state of an energy object, is improved to such an extent that it acquires the ability to combine information up to the maximum possible physical limit. In other words, relay protection is endowed with the ability to operate with information in multidimensional space, although each individual relay remains with the response characteristic, traditionally set on the plane of a two-dimensional, in the particular case of a complex signal. Specific means of achieving this goal are as follows. Instead of each of the previously used relays, a group of relays similar to it is introduced. The analogy between the main and additional relays forming the indicated group is that each of them is switched on to the same two-dimensional signal and their response characteristics are set on the same plane of the given signal. In addition, they form executive relay groups, including in each of them one representative of each group of similar relays. The executive group operates according to the AND circuit, and different executive groups act independently from each other according to the OR circuit, which creates the output signal of the relay protection.

The crucial role in the proposed method is played by the procedure for setting the response characteristics of individual relays. On the plane of a two-dimensional signal, a certain number of cells of a given shape are isolated. Some of them will serve as response areas for those similar relays that are included in a two-dimensional signal. The cells are numbered, and from the numbers of different planes they make up an array of codes. From it eliminate those codes that can give a false positive relay protection. They are detected by conducting protection tests on simulation models of energy consumables in alternative modes to the controlled one. For example, for distance protection, alternatives include load conditions, as well as short circuits outside the zone, "behind", in another circuit of a double-circuit line.

After excluding codes of alternative modes, redundant codes that do not occur with controlled closures remain in the general array. They are also excluded, so as not to expand the coverage of the protection without need. To do this, they conduct protection tests on the models of the energy object in a controlled mode, determine the corresponding response codes and only save them in an array of codes, and exclude everything else. The last fundamentally important point is to specify the response areas of each individual relay, which, on the one hand, is included in a group of similar relays, and on the other hand, in one or, possibly, several groups of executive relays. The number of similar relays is chosen equal to the number of response cells on the plane of the corresponding two-dimensional signal, and one of the cells is assigned to the response area of one of the similar relays

Additional claims specify the shape of the cells and the order in which they are selected. The simplest form is quadrangular, the simplest is rectangular with an arrangement parallel to the coordinate axes. This form is convenient for representing complex signals with their orthogonal components. For presentation in polar form, it is more convenient to have curvilinear cells bounded by circles with centers at the origin at the rays emanating from there.

Separately, a path is proposed for the formation of common response areas on each of the planes. It is advisable to set them in the form of simply connected figures when the response cells are adjacent to each other. Cells can be of different sizes, first set one of the largest cells on each plane, and then cells of decreasing sizes are attached to it.

A variant with a different number of cells on different planes is also proposed, which simplifies the implementation of the method. Different two-dimensional signals carry unequal amounts of information. So, with an interphase circuit, the largest amount of information is concentrated in the resistance at the relay input of the damaged interphase channel, and the resistance of other channels is informationally poorer. Therefore, in this case, it is advisable to take more cells on the plane of the relay group of the damaged channel than on the planes of other relays.

Figure 1 presents the structural diagram of the proposed method, and figure 2, 3 - various options for setting the characteristics of the operation of elementary relays; in figure 2 all cells have common borders, and in figure 3 - not all.

The structural diagram of the proposed method includes groups of similar relays 1, 2, 3. The same relays in a different combination form the executive groups 4, 5, 6. Groups of the first type can consist of a different number of elementary relays. So, in groups 1 and 2 there are three relays 7-9 and, respectively, 10-12, and in group 3 there are only two relays 13, 14. But the executive groups always include the same number of elementary relays - one each each group of similar relays. Thus, the number of relays in each executive group is equal to the number of elementary relays in the largest group of similar relays. A small group of similar relays will be represented by the same elementary relay in more than one executive group. So, in this circuit, the relay 14 is simultaneously included in the executive groups 5 and 6. The outputs of all the relays of the same executive group are connected by the circuit I. In Fig. 1, these are blocks 15-17, the outputs of which, according to the OR 18 circuit, form the output signal of the relay protection . The input two-dimensional signals to all relays come from the converter 19. In the working state, the converter is connected to the power object 20, from which signals proportional to the currents and voltages of the mode in which the power object is located come from. A priori information can enter the Converter 19 through other channels not shown in the diagram.

In the process of tuning (training) of relay protection, when the response characteristics of elementary relays are formed, the converter 19 switches to the models of the power object: the model of the controlled mode 21 or the model of the alternative mode 22. Switching is performed by keys 23-25.

The diagram of figure 1 shows three two-dimensional signals a, b, c, which are displayed on their planes 26-28 (figure 2 and 3). For simplicity, a small number of cells are indicated: three for signals a and b, and only two for signal c. The cells form 3 × 3 × 2 = 18 codes. Each cell is the response area of one relay; The following correspondence is accepted:

Relay number Cell number 7 al 8 a2 nine a3 10 b1 eleven b2 12 b3 thirteen s1 14 c2

According to the proposed method, the number of cells on each plane, their shape, size, location are set in advance on the basis of experience. The lack of experience can affect the number of cells, it will be overestimated, but the goal - increasing the sensitivity of the defense - will nevertheless be achieved in any case.

After setting the cells, the number of elementary relays and the response characteristics of each of them become known. In this case, there will be eight such relays, of which three relays 7, 8, 9 are connected to signal a, three relays 10-12 to signal b and two relays 13, 14 to signal c. But the number and composition of executive groups is not yet known. It is determined after tuning (learning) the relay. The first stage of tuning consists in exposing the converter 19 to a model of an energy object 21 that simulates various alternative modes. Each mode is displayed on all planes of two-dimensional signals. The points of this alternative mode may not fall into the selected cells at all, or they may partially get into them, i.e. not on all planes. None of the codes involved will respond to this mode. However, there is such an alternative mode, the points of which will appear in any selected cells on all planes simultaneously. This will mean specifying one of the available codes. Suppose the points of the alternative mode are in cells a1, b2, c2; we take the symbol of the corresponding code a1-b2-c2. Obviously, it will have to be excluded from the general array of codes, since getting into this code in the future should not lead to triggering of protection. Suppose that during tests on a variety of alternative modes, a similar fate befell another part of the codes, say, such as: a1-b2-c1, a1-b3-c2, a2-b1-c2, a2-b2-c1, a2-b3- c2, a3-b1-c1, a3-b1-c2, a3-b2-c1, a3-b2-c2, a3-b3-c1. then it turns out that out of the 18 available codes, the alternative modes took 11. There remain 7 codes where protection can be triggered in principle.

At the second stage, the protection settings check the feasibility of including the remaining codes in the protection response area. The Converter 19 is switched to a model of the energy object 22, simulating a controlled emergency mode. Tests will reveal that part of the remaining codes that corresponds to this particular mode. Suppose these are codes a1-b1-c1, a2-b2-c2 and a3-b3-c2. There are only three, and there are seven left. So four are empty; neither alternative nor controlled regimen fall into them. In this example, these will be codes a1-b1-c2, a2-b1-c1, a1-b3-c1, a2-b3-c1. They are also excluded from the array of response codes.

At the third stage, relay executive groups are formed. The response code a1-b1-c1 corresponds to group 4, and the codes a2-b2-c2 and a3-b3-c2 correspond to groups 5 and 6. This completes the setting of relay protection, and it will be ready for operation. If during the tests no alternative modes were missed, then the false operation of the proposed protection is fundamentally impossible. As the size of the cells decreases and their number increases, the recognition ability of the defense increases more and more, striving for a physical limit - the recognition of the controlled situation. Recognizability is a property of the object itself and at the same time the limit of the recognition properties of relay protection [5].

The most simple to implement relays with the characteristics of a quadrangular, especially rectangular shape. The following in simplicity are characteristics bounded by circular arcs and rays.

In order not to overestimate the number of protection tests in alternative modes, it is proposed to additionally check the simply connectedness of the response areas obtained as a result of setting.

For example, if it turned out that on the planes of the two-dimensional signals of Fig. 3 in the response codes there was no cell a2 or b2, or both, then the simply connected nature of the common response area would be broken either on plane 26 or 27, or on both other. It is possible to restore simply connectedness by abandoning the activation codes containing cell a1 or a3 (in the absence of a2), as well as from b1 or b3 (in the absence of b2).

To simplify protection, it is advisable not to overestimate the number of response codes that directly depends on the size of the cells. It is proposed to carry out recurrent tuning of relay protection: first on the largest cells, covering a certain part of the controlled states of the energy object, then on smaller cells.

Another measure that simplifies protection is to select a different number of cells on the planes of different two-dimensional signals. Two-dimensional signals in the form of complex resistances are most suitable for protecting power lines. It is proposed in this case to determine the type of damage and the damaged phases of the power facility, revealing as a result of the damaged line channels. With a single-phase fault, this will be one of the phase channels, with an interphase one of the linear channels, and with a two-phase earth fault there will be three such channels: two phase and one linear. It is proposed to select a larger number of cells on the resistance planes of damaged channels than on the planes of undamaged channels. The proposed method is universal in that it does not depend on the type of object.

Only two-dimensional signals vary, which can be complexes or a pair of real quantities, for example, samples of current and (or) voltage. Universally, and setting the response characteristics, which occurs by setting (training) protection in alternative modes to controlled, i.e. forbidden to operate, and directly in a controlled, where it is desirable to provide high sensitivity. The experiments confirm the possibility of increasing the sensitivity of the protection acting by the proposed method, up to the physical limit - recognition of short circuits.

Information sources.

1. USSR Copyright Certificate No. 66343, cl. H 02 H 3/28, 1944.

2. Schneerson E.M. Remote protection. M .: Energoatomizdat, 1986 (p. 88-89).

3. RF patent No. 2066511, cl. H 02 H 3/40, G 01 R 31/08, 1992.

4. RF patent No. 2149489, cl. H 02 H 3/40, G 01 R 31/08, 1999.

5. Recognition of power transmission damage. Part 1-3, Electricity, 2001, No. 2,3,12.

Claims (6)

1. The method of relay protection of an energy facility by jointly converting the measured electrical quantities and a priori information about the energy facility into two-dimensional signals and their influence on the relay executive group containing one relay for each signal, specifying the response characteristics of each relay on the plane of the corresponding two-dimensional signal, combining the output signals relay of the executive group by a logical operation AND, using its result as an output signal of relay protection and checking the failure of protection s on models of an energy object in alternative modes to controlled, characterized in that, in order to increase sensitivity, separate cells on the plane of each two-dimensional signal, make up an array of codes from the numbers of cells of different planes, test the protection on models of an energy object in alternative modes and determine the appropriate to them failure codes, which are excluded from the array of codes, conduct protection tests on the models of the power facility in a controlled mode, determine the corresponding codes Attacks store them in an array of codes, and the remaining codes are excluded, make up groups of similar relays, for which each main relay is duplicated by additional relays similar to it, and additional groups of executive relays according to the number of stored codes, and each relay group includes one relay from of each group of similar relays, take as the response areas of the relay the cells of the corresponding code on the respective planes, combine the output signals of all the relays with the same additional use itelnoy group logic operation AND, and the output signals of all the executive groups - OR operation, the result of which complement output signal relaying. 2. The method according to claim 1, characterized in that on the plane of each two-dimensional signal allocate cells of a quadrangular shape. 3. The method according to claim 2, characterized in that the rectangular cells are distinguished, the sides of which are parallel to the coordinate axes in the plane of each two-dimensional signal. 4. The method according to claim 2, characterized in that the cells are defined bounded by circles with centers at the origin and rays emanating from the origin. 5. The method according to claims 1 to 4, characterized in that the response areas of the relay on each plane are set in the form of simply connected figures, which are made up of cells of different sizes adjacent to each other, first they determine one of the largest response cells on each plane, and then cells of decreasing sizes are attached to it and to each other. 6. The method according to claims 1-5, characterized in that complex resistances are used as two-dimensional signals, the type of damage and the damaged phases of the energy object are determined, and the largest number of cells is isolated on the plane of the damaged channel: corresponding phase when single-phase, corresponding linear when interphase short circuit, two phase and one linear when two-phase earth fault.

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