RU184111U1 - Device for modeling asymmetric modes and predicting the behavior of digital protections in electrical installations with isolated neutral - Google Patents

Abstract

The device relates to the field of electrical engineering related to the calculation, configuration and testing of digital directional protection in electrical installations with isolated neutral, primarily in electrical installations up to 1 kV with isolated neutral. The technical result is the expansion of the scope of devices to simulate single-phase earth faults in an open line electric network is achieved through the implementation of the model of a complex three-phase closed electric network with two power sources in the form of transformers and digital th microprocessor relay protection, are included in one of the modeled lines. At the same time, a programmable element IV is included in the device (Fig. 1), made with the possibility of calculating the electric values of the modes of the virtual electric circuit with the topology and parameters adequate to the assembled physical model. The step of calculating the electrical values of the programmable element is chosen equal to the sampling period of the digital protection unit. This makes it possible to predict the behavior of the block protections in abnormal modes by calculating the values of these modes at different points of the virtual network and verify the accuracy of the calculations by modeling the actual asymmetric modes recorded by the oscilloscope of the block at similar points in the physical model of the network.The device compares the calculated and experimental values of the abnormal modes; the calculated and actual behavior of the block protections in these modes and makes it possible to adjust the response parameters of the block protections and the program element protections, achieving the required protection sensitivity, selectivity and speed. The device is formed of resistive-inductive-capacitive elements I (Fig. 1), modeling a complex closed electrical circuit. An example of the practical application of the device is given. 15 ill., 4 tab.

Description

The device relates to the field of electrical engineering, namely to the design, operation of electrical installations with insulated neutral, namely to the calculations, testing, configuration and operation of directional protection and control devices in these electrical installations and, above all, in electrical installations up to 1 kV. Design and operation of electrical installations with up to 1 isolated neutral are regulated by regulatory documents: Electrical Installation Rules. M. Energoizdat. 2010 - [1], as well as departmental documents: Guidelines for the design of power supply systems up to 1 kV with isolated neutral at capital construction facilities of the Ministry of Defense. M.-SPb, 2008 - [2], the latter specify the regulatory requirements, having a recommendatory nature. The main recommendations in this case come down to clarification of methods for continuous monitoring of the general state of insulation and selective (directional) monitoring of the insulation of elements of an electrically connected network in order to quickly find damaged elements. At the same time, it is recommended to use devices for these purposes that monitor the phase relations of currents and zero sequence voltages. Famous: Schneerson E.M. Digital relay protection. M .: Energoatomizdat, 2007 - [3]; Digital block of relay protection of BMRZ-100 type. Manual. DIVG.648228.024 RE. 2013 - [4] - microprocessor-based monitoring and protection devices that are intensively implemented in electrical installations include the implementation of the aforementioned directional zero-sequence power control, as well as the oscilloscope functions of abnormal modes, which makes it possible to adjust their settings in operating conditions using fixed real electrical magnitude of emergency conditions in the places of installation of protection.

The creation of new and modernization of existing electrical installations is associated with the need to predict at the design stages the behavior of the protection units in the modified initial circuits and with other technical characteristics of their elements. This requires knowledge of primary electrical quantities, including their phase relationships, at the installation sites of the protection units in various modes of operation of the protected elements and possible options for the original circuit of the electric network (ES). Mathematical models based on analytical (numerical) methods for calculating regimes are called upon to implement this: Losev SB, Chernin AB Calculation of electrical quantities in asymmetric modes of electrical systems. M. Energoatomizdat, 1985 - [5]; Fedoseev A.M., Fedoseev M.A. Relay protection of electric power systems. M. Energoatomizdat. 1992 - [6]; Glukhov O.A., Mikhailov A.K., Fominich E.N. Insulation monitoring systems in power supply systems with insulated neutral. EMC technology. 2007. No3 (22) - [7]; Vladimirov Yu.F. Calculations of asymmetric modes as applied to the analysis of safety conditions in electrical installations. SPb .: VI (IT) VA MTO. 2014 - [8].

The latter, however, require confirmation of the reliability of the calculations by experiment (experiment). The possibilities of implementing most of these experiments in existing electrical installations are limited.

In these cases, devices for the physical modeling of such modes on an accessible elemental base can contribute to the successful use of digital protection and control devices, predicting their behavior, as well as improving methods for calculating modes: Report on the research work "Infinity." St. Petersburg: VISI, 1996, No. 548904 - [10]; Vladimirov Yu.F. On the experimental determination of the parameters of the single-phase circuit mode on the physical model of the electric network line. St. Petersburg: VITU, 1999, No. 559629 - [11]. The use of such models makes it possible to compare experimental measurements of the electrical quantities of the simulated modes with the calculations performed by the above methods and thus contribute to the improvement of the latter. In addition, the implementation of such complex modeling with the help of special devices in the form of stands for testing and tuning microprocessor-based protection devices can significantly improve the training capabilities of personnel designed to perform calculations, configuration and operation of protection and control devices in electrical installations.

The prototype of the claimed utility model is “A device for the physical simulation of electric power systems of 0.4 kV” [10] (p. 3, 4)], consisting of capacitive, resistive, inductive elements that implement the model of the main line of a three-phase electric network with an isolated neutral with one power source in the form of a transformer. Additionally, the work of the prototype [10] explains the article: Vladimirov Yu.F. On the experimental determination of the parameters of the single-phase circuit mode on the physical model of the electric network line. St. Petersburg: VITU, 1999, No. 559629 - [11].

The disadvantage of the prototype [10] and analogue [11] is the limited scope: the lack of the ability to simulate asymmetric modes in complex (closed, open) electrical installations in which the use of directional protections is necessary, associated with the need to control the phase relationships of electrical quantities of abnormal modes. In addition, the device does not directly control the behavior of real protections in simulated abnormal modes. The control is limited to an analytical comparison of the calculated values of the protection operation parameters with the measured devices by the operating values of the abnormal conditions.

The essence of the claimed utility model is that the "Device for modeling asymmetric modes and predicting the behavior of digital protections in electrical installations with isolated neutral" (hereinafter referred to as the "device"), also consisting of capacitive, resistive, inductive elements and switches, implements a complex three-phase electric a circuit with lumped parameters with two power supplies in the form of transformers and a “digital microprocessor relay protection unit” (BMRZ) (hereinafter “protection unit”) included in one and simulated lines. At the same time, a programmable element is included in the device, made with the possibility of calculating the electric values of the modes of the virtual electric circuit with the topology and parameters adequate to the assembled physical model; the step of calculating the electrical values of the programmable element is chosen equal to the sampling period of the digital protection unit. The device is connected to the analog inputs of the protection unit, which is configured to switch to control and oscillograph parameters of the abnormal mode on an adjacent line. The device has an algorithm for comparing the values calculated in the programmable element, taking into account the switching moment determined by the oscillogram of the tested protection unit, and the actual electrical values of the simulated abnormal mode, recorded by the oscilloscope of the protection unit. According to the results of the comparison algorithm, the device makes it possible to adjust the protection behavior by changing the response parameters of the digital protection unit, as well as adjust the programmable element program, achieving the required protection characteristics under the conditions of selectivity, sensitivity and speed.

Technical result: expanding the scope of the device is achieved by eliminating the disadvantages of the prototype [10], it becomes possible to model the main typical abnormal conditions in a complex (closed) electrical circuit and to predict the behavior of real digital directional protections using the programmable element included in the device by comparing calculated and actual values of the modes and adjusting the parameters of the operation of the protections in these modes.

In FIG. 1 is a functional (explanatory) diagram of a device, and FIG. 2, 3, a schematic diagram and layout of the front panel of the stand physically realizing the device. In FIG. Figure 4 shows the experimental dependences obtained during testing of the device, which make it possible to select the protection unit operation parameters acceptable under the conditions of selectivity and sensitivity under the conditions of a simulated mode of a single-phase earth fault (OZZ).

Utility Model Description

A device designed for the physical modeling of asymmetric modes in electrical installations is implemented on the basis of chain equivalent circuits for lines of a complex three-phase electric circuit formed from capacitive-resistive elements simulating transverse passive parameters (phase capacitance relative to the ground and interphase capacitance of lines) and inductive-resistive elements, modeling the longitudinal parameters of the lines (Fig. 1); (resistors R _i and capacitors C _j in the drawing of Fig. 2). In one of the electrical circuits, simulating the cable power line w1 (Fig. 1), the protection unit IV (BMRZ-101) (Fig. 1), (Fig. 2, a) is included. The main purpose of the model is the modeling of asymmetric modes (primarily single-phase earth faults in networks with isolated neutral), as well as complex modes in closed - open EES circuits for the purpose of testing and tuning digital directional protection and control devices. Physical modeling of single-phase, two-phase, and three-phase earth faults is performed in lines w1, w2, at any of ten points selected on the model, any of three phases 1 (A), 2 (B), 3 (C) at each of points III ( Fig. 1). In this case, the topology of the initial scheme of the physical model can be changed in relation to the specific conditions of the network under study by selecting model options using the switches (toggle switches) Q (Fig. 1) and using distorting resistances in the program of computing element II (Fig. 1) (closed, open, with one, two power sources (transformers), etc.).

In the device, the control of the parameters of the mode in zero sequence at the installation point of the device is carried out without a zero sequence current transformer (TNP) - by directly connecting the channels of the zero sequence of the tested digital block in the reverse circuit 9 of the physical model (Fig. 1).

In addition, the device provides the ability to control and oscillograph parameters of simulated abnormal modes and on an adjacent line by switching the analog channels of the digital protection unit to another line w2 (by switching to the N1 or N2 position of a special toggle switch (Fig. 3)).

The device includes a programmable element II (Fig. 1), which allows you to calculate the electrical values of the asymmetric modes of the virtual electrical circuit, the parameters of which and the topology are selected equivalent to the physical model.

The operation settings of the protection unit for current, voltage and power direction are determined in this computing element in the dialogue mode by choosing from among the proposed values of the maximum sensitivity angles ϕ _{0 (max.h)} required by the selectivity condition, as well as using printouts of the calculated electrical quantities of 3U mode ₀ , 3I ₀ , S ₀ , P ₀ , ϕ ₀ at the installation location of the block. The results of the simulated mode in the device connected to the analog inputs of the protection unit IV (Fig. 1) are compared with the calculated values of the electrical values of the mode of the computing element and with the actual functioning of the protection recorded by the oscilloscopes of the protection unit. The settings of 3U ₀ , 3I ₀ , ϕ _{0 (mh) of} mathematical model II (Fig. 1) and the analog settings of block IV (Fig. 1) are adjusted based on the requirements of selectivity, speed, and sensitivity, followed by a repeat of the calculation and experiment on a physical model until the desired results are obtained.

Practical implementation of the use of the model

The calculation, for example, of the OZZ mode of any of the phases at an arbitrary point of the protected line w1 is performed with the open (closed) state of the initial circuit of the electric network (Figure 1, 5) and the given values of its passive parameters (table 1). In this case, in the general case, in the absence of information about the nature and degree of natural asymmetry of the parameters of the three-phase electrical installation, and the magnitude and direction of the zero sequence voltage corresponding to this asymmetry, to the moment in time preceding the OZZ mode, the initial calculation can be performed under zero initial conditions. Based on the calculated values of the electrical quantities of the abnormal mode at the point of insulation damage and at the installation site of the BMRZ-100 unit, the operation settings of the directional insulation monitoring device are determined based on the conditions: I _{0 (s.z)} ≥k _n ⋅I _{0 (w2)} at OZZ on the line w1; - (90 ° -ϕ _{0 (max.h)} ) ≤ϕ _0р ≤ (90 ° + ϕ _{0 (max.h)} ), P _s.c. = U ₀ .I _0с.⋅ ⋅cos (ϕ ₀ -ϕ _{0 (max.h)} ) which are set in the protection unit menu “analog settings”.

With these settings, the OZZ experiment of the given phase is performed at the design point on the line w1 of the physical model and the response (failure) of the block protection is recorded.

The actual switching moment recorded by the oscilloscope of the tested protection unit (this moment is determined by the mod and arg of the phase voltage of the previous mode U _1jA ^cp at the time t _{0 of} switching) makes it possible to determine the electrical values of the SCR mode at the installation site under changed initial conditions (with a real voltage of zero sequences on the equivalent capacity at the time preceding the switching - u _{with (0)} ). After that, it is possible to clarify the settings for the operation of the protection unit, taking into account the start-up and operation times of the protection recorded by the oscilloscope and

evaluate the sensitivity of protection in the considered mode K _{h (i)} = (С _0Σ -С _{0 (w1)} ) / (k _н ⋅С _{0 (w1)} )> K _ч.min = 1.25; To _h ( _P ) = _{ΔР ozz} ( _calculation ) / P _s.z > To _{h (P) min} = 2.0.

Calculations and modeling of the SCR can be performed, if necessary, for maximum and minimum modes, various options for the topology of the circuit, different r _per in the place of insulation damage, and various switching times.

The claimed device allows you to perform:

при заданных значениях модуля и с точностью до 2nπ аргумента комплексного числа

. Аналитические выражения для вычисления электрических величин моделируемых режимов в устройстве получаются после замены компоненты ωt в написании формул алгоритма дискретизированным временным параметром

;- calculation of electrical quantities of typical asymmetric modes and settings of the protection operation based on the algorithm: Vladimirov Yu.F., Fominich E.N. Mathematical modeling of the modes of electric networks with isolated neutral to predict the behavior of digital protection devices. Military engineer. St. Petersburg 2017, No. 1 (3) [9] in a programmable element II (Fig. 1) included in the device in question; the equivalent energy source (EMF of the previous symmetric mode at the point of asymmetry in the circuit) is represented as a sequence of discrete values of a vector rotating on a complex plane with an angular frequency ω ₀

for given values of the modulus and up to 2nπ of the argument of the complex number

. Analytical expressions for calculating the electrical quantities of the simulated modes in the device are obtained after replacing the component ωt in writing the formulas of the algorithm with a discretized time parameter

;

- simulation of ES modes (Fig. 5, a) on a three-phase physical model that implements chain diagrams of two lines w1 and w2 of the electric network, and which is a set of r, L, C - elements and power sources in the form of two transformers T1 and T2;

,

, где i=1, 2, 0 (составляющие прямой, обратной, нулевой последовательностей величин режима, соответственно); j=1, 2, 3, …10 - точки на физической модели; m=1, 2, 3 (фазы А, В, С, соответственно) в каждой из точек 1, 2, 3, 4, 5 линий w1 и w2 и сложных режимов одновременных (последовательных) замыканий в различных точках модели;- modeling on a physical model of asymmetric modes

,

, where i = 1, 2, 0 (components of the direct, reverse, zero sequences of mode values, respectively); j = 1, 2, 3, ... 10 - points on the physical model; m = 1, 2, 3 (phases A, B, C, respectively) at each of points 1, 2, 3, 4, 5 of lines w1 and w2 and complex modes of simultaneous (sequential) closures at different points of the model;

- the ability to change the topology of the original circuit by changing the positions of the toggle switches and switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 (Fig. 1) located on the front panel of the stand (Fig. 3);

- the possibility of taking the current-voltage and angular characteristics of the tested protection unit using a plug-in phase regulator;

- connecting a PC to the bench using the capabilities provided by the studied units of protection, fixing and oscillography of the actual electrical quantities of abnormal modes, modeled in the device with the transfer of information to a higher level computer if necessary.

Information confirming the feasibility of implementing a utility model

An example of the calculated forecasting of the protection behavior of a block in one of the OZZ modes with the subsequent modeling at the stand of this mode is given.

Example

For the initial circuit ES - 220/36/21 V with isolated neutral (Fig. 5, a), it is required to determine the analog settings of the operation of directional protection from the protection zone of a BMRZ-101 type unit installed on the head section of the w1 line. A variant of the topology of the original circuit: open on switch Q6 with two transformers operating in parallel (switches Q5, Q7, Q8, - closed). It is necessary to check using the device the selectivity of the protection response, which is activated with the action on the signal, by modeling the phase-dependent phase-difference protection zone 3 (C) at point 4 of line w1 of the physical model (at point 4 of line w1 of the equivalent circuit (Fig. 5, a, c)) and failure protection in case of SCD of the same phase 3 (C) at point 2 on line w2 of the device (at point 2 of line w2 of the equivalent circuit (Fig. 5, a, c)).

a) On the calculation model ('' F: \ Calculation model 12 → (2) 36-21V → Progrsq → Progrsd (1КB) → View → Project Explorer) with parameters equivalent to the physical model (Fig. 5, b, c and table 1 ), for an arbitrary time instant of the initial symmetric mode, we calculate the parameters of the phase 3 (C) SCR mode at a given point 4 of the circuit with r _per = 0.01 [Ohm], as well as the calculated values of the considered SCR mode directly at the device installation site: on the elements 3, c and 2, in the equivalent circuit (Fig. 5, c) and taking into account the calculated value of the maximum sensitivity angle for the switching point 4 ϕ _{0 (max. )} = 84.4 ° (table 2), we enter in the dialogue mode from among those offered by the program ('' F: \ Calculation model 12 → ... Module 4) the nearest maximum angle

. После чего выполнив распечатку результатов расчета находим значение угла максимальной чувствительности и непосредственно на входе в блок защиты (на элементах 2, в; 3, в схемы замещения (фигура 5, в).sensitivity

. After that, after printing the results of the calculation, we find the value of the maximum sensitivity angle and directly at the entrance to the protection unit (on elements 2, 3; 3, in the equivalent circuit (figure 5, c).

b) We also verify the calculated fulfillment of the condition for the operation of the directional protection of the unit from the _{emergency protection zone} , formulated by the inequality _{Pzz (3.2)} > 0. The calculations indicate the predicted selective operation of the directional protection of the unit during the fault protection on the w1 line (since Р ^{(3, в; 2, в)} _{ОЗЗ (calculation)} > 0) and on the failure of the protection during the fault protection on the w2 line (Р ^(19.4) _{OZZ (calculation)} <0).

c) In the menu of the protection unit, we establish the calculated analog settings of the protection operation, guided by the calculation results obtained above in the computing element (items a, b):

3U _{0 (s.z)} = 5 V (minimum permissible setting according to the conditions of the unit manufacturer), 3I ₀ ( _s.z ) = 3I ₀ = 0.05 A (detaching from possible unbalance currents in zero sequence); in the first approximation, we take ϕ _{0 (max.h)} = 75 °, t _OZZ = 0.02 s; and the corresponding positions of the comparators - key S26 - is closed; the keys S21, S24, S25, are open.

d) On the physical part of the model of the ES device, we simulate the phase-delay mode of phase 3 (C) at a given point 4 of the line w1. We fix the selective operation of the protection - the glow of the LEDs "8" and "1", "2" of the protection unit.

Based on the oscillogram (Fig. 6, a) and the block vector diagram (Fig. 7), we determine the actual (experimental) parameters of the asymmetric mode, including for the time t ₁ = 0.02 s (n = 48) -3i ₀ and voltage 3u ₀ , as well as the experimental value of the angle ϕ _{0 (experimental)} at the installation site of the protection unit: ϕ _{0 (experimental)} = -60 ... -65 °. In addition, we determine from the waveform the magnitude and direction of the phase 1 (A) voltage of the symmetrical mode at the time of switching U _1A ^cp = 12, 9612-j7.1845 V, as well as the magnitude and direction of the zero sequence voltage U ₀ at the input to the protection unit at the time switching t ₀ . This makes it possible to change the calculated initial conditions at the time of switching in the program and to repeat the calculation of the electrical quantities of the considered mode of the SCR phase 3 (C) at point 4 of line w1 with updated data. We note here that the settings of the directional protections are selected in this case based on the values of the electric values of the steady state (in any case, after attenuation of the free components of the transient process) and these refinements do not change the calculated direction of power at the place of installation of protection. Table 3 shows the electrical values of the regime under specified initial conditions.

e) Based on a comparison of the calculated and experimental data (see the waveforms and the vector diagram of the block (Fig. 6, 7) and the calculated values of the mode values (tables 2, 3), we see that the actual angle ϕ _{0 of the experimental} differs from the calculated angle by about 9 ° ... 12 °. Accordingly, the adopted analog setting of the device ϕ _{0 (max. H)} = 70 ° must be changed to a value ϕ _{0 (experimental)} = 60 ... 65 ° in order to obtain the maximum sensitivity of protection.

Given that the calculated values of the electric values of the mode at the entrance to the protection unit at n = 48 (t = 0.02 s) (table 3 and Fig. 10) differ from

valid, registered by the oscilloscope unit for the same point in time (Fig. 6, 7) no more than 9 ... 11% of the remaining analog settings can be left unchanged.

f) Similarly to paragraphs. a) ... e) we perform the calculation ('' F: \ Calculation model 14 → (2) 36-21V → Progrsq → Progrsd (1KB) → View → ProjectExplorer) of the OZZ mode at point 2 on the w2 line of the model (at point 2 of the w2 line equivalent circuit (Fig. 5, c)) and make sure (see table 4) that at the given settings the directional protection of the unit installed on the w1 line should not be triggered (we have the reverse positive direction of the zero sequence power on the elements of the equivalent circuit 3, in , 2, in (Fig. 5, c) (negative sign of power P ₀ = -2.3 W (table 4)).

g) To verify the correctness of the directional protection settings, the OZZ experiment is also performed on the w2 line (at point 2). At the same time, the block does not fix the “start of protection” and “call BMRZ”, which is confirmed by comparing the waveform and the vector diagram of the block (see Fig. 8, a; 9) in this mode with the calculated values of the electrical quantities of this mode given in table 4) .

Thus, the calculated dependences (Fig. 10), compared with the experimental waveform graphs, confirm the accuracy of predicting the selective operation of directional protection from the OZZ according to the parameters of the zero sequence of the abnormal mode for the given parameters and calculated settings).

In addition, we see that, in principle, it is possible to use the transient parameters in the zero sequence to implement directional protection in the case under consideration, since (see the waveform in Fig. 6, a) the first half-waves of the instantaneous current and voltage of the zero sequence 3i ₀ , 3u ₀ have signs of the same polarity at the place of installation of protection, in contrast to the parameters of the same mode on the undamaged w2 line (Fig. 8, a) where the instantaneous values 3i ₀ , 3u ₀ have signs of different polarity at the time of switching t ₀₊ (period

sampling T = 0.41666 ms of the protection unit provides, when fixing abnormal conditions of the OZZ, the time offset from the influence of wave (pulsed) processes).

We also note that according to the sensitivity conditions according to the zero-sequence power criterion [1], the SCR through r _per ≈10 [Ohm] appears to be limiting for the given circuit parameters and permissible settings for the protection operation (with the calculated r _ut = 100 [Ohm], for example, we have: C _h = (P _{cc (min)} = 2.9 [V] ⋅0.1 [A] ⋅0.9) / (P _cc = 5 [V] ⋅0.05 [A] ⋅0.9 ) = 1.2 <K _{h. dop)} with K _{h. ext} > 2.0.

We write down the basic settings for the operation of the protection against OZZ on the feeder w1 and check the sensitivity of the protections [1]:

I _c.z = k _n ⋅3⋅314⋅C _{0 (class 1)} ⋅U _0k ⋅10 ^-6 = 2⋅3⋅314⋅0.0626⋅225.96⋅10 ^-6 = 0.0266 A;

(here the reliability coefficient (detuning) is taken equal to k _n = 2.0);

t _c.z = 0.05 s (with the minimum allowable t _ozz = 0.01 s);

R _y = 0.6 MΩ; (see clause 6.1.5)

ϕ _{0 (max.h)} = + 85 ° (see clause 6.1.7)

P _s.z. = U ₀ .I _c.s. ⋅cos (90.7 ° -85 °) = 225.96⋅0.0266⋅0.99 = 5.95 W.

Current Sequence Protection Sensitivity

K _{h (i)} = (С _0Σ -С _{0 (cl1)} ) / (k _n ⋅С _{0 (cl1)} ) = (0.4255-0.0626) / (2.0⋅0.0626) = 2, 9;

K _{h (i)} > K _h.min = l, 25.

Power Sequence Protection Sensitivity

K _{h (P)} = ΔP _{OZZ (calc)} / P _s.z = 17.3 / 5.95 = 2.9; those. K _{h (P)} > K _{h (P) min} = 2.0.

Evaluation of technical results

The device makes it possible to confirm the reliability of the results of calculating the electrical quantities of abnormal modes taking into account the known limitations for modeling real ES substitution circuits with lumped parameters and within the limits of engineering errors of calculations, as well as to verify the accuracy of predicting the behavior of digital protection units when exposed to real electrical variables current and protection parameters set in the block menu.

Description of the figures of the drawings

In FIG. 1 is a functional (explanatory) diagram of a device for modeling asymmetric modes and predicting the behavior of digital protections in electrical installations with isolated neutral; circuit elements are presented in the following positions:

w1, w2 - name of cable lines simulated by the device of the electric network;

Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 - designation of the toggle switches simulating circuit breakers;

T1, T2 - transformers;

I - The physical part of the ES model (general designation);

II - Computing element of the device (general designation);

III - An elementary section of line equivalent circuits;

IV - microprocessor relay protection unit type BMRZ-100;

1, 2, 3, 4, 5 - numbers of elementary sections of lines according to the schemes of simulated lines W1 and W2;

Z _a , Z _b , Z _c - longitudinal electrical resistances of the phases of the lines modeled by active resistances (resistors);

Z _N - longitudinal electrical resistance of the reverse current circuit modeled by resistors;

Y _a , Y _b , Y _c - transverse electrical conductivity of the phases of the lines, modeled by capacitors;

C ₀ - capacitors;

9 - reverse current circuit of the circuit of the w1 ES line connected to the analog channels of the zero sequence current 3I ₀ of the protection unit;

P - designation of the transformation and distribution algorithm, calculated for the point of occurrence of the asymmetry of electrical quantities, along the branches of the zero sequence equivalent circuit;

in FIG. 2 shows a schematic diagram of a device. Elements of the scheme are presented in the following positions:

K _1, ... K ₁₂ - electromagnetic relay coils;

BUT; V - ammeters, voltmeters;

SA1, SA2, ... SA11, ... SA16 - current relay contacts and switching contacts of toggle switches and switches;

HL1, ... HL16 - LEDs;

QF1 - three-pole switch;

C _1, C ₂ , ... C ₄₆ - capacitors simulating the transverse conductivity of the phase insulation (each capacitance, except C ₁₁ , C ₁₂ , C ₁₃ ) is equal to C ₀ j = 2.0 μF; C ₁₁ = C ₁₂ = C ₁₃ = 46.5 μF;

R _1, R _2, ... R ₆₄ - resistors simulating longitudinal line resistance; resistance values are given in the drawing;

X _A1 , ... X _A12 - terminal contacts;

in FIG. 2, a drawing of the connections made to the terminals for external connections provided in the BMRZ-101 protection block is given;

in FIG. 3 shows a diagram of the front panel of the device stand. Elements of the scheme are presented in the following positions:

On - an automatic machine and a stand-on indicator;

AB, BC, CA - interphase voltage switch of the voltmeter;

N1, N2 - switch of the protection unit (line w1-N1 - line w2-N2);

A ₁ , B ₁ , C ₁ - selector switch of a special phase on the line W1; 1, 2, 3, 4, 5 — switch of the position of the point of simulated asymmetry on the line W1;

A ₂ , B ₂ , C ₂ - switch select a special phase on the line W2; 1, 2, 3, 4, 5 — switch of the position of the point of simulated asymmetry on the line W2;

OZZ, MTZ - protection operation LEDs;

RPO-RPV - switch relay repeater position of the circuit breaker;

in the upper left corner there is a protection unit; LED indication of the protection unit is determined by the manufacturer [4];

in the lower left corner are the terminals of the transformers T1 and T2: A, B, C, a, b, c, X, Y, Z, x, y, z; It is possible to switch transformer winding connection schemes;

at the bottom of the stand there is a mimic diagram of the simulated electrical installation with LEDs signaling the position of the switches Q1, Q2, Q3, Q4 and asymmetry modeling points selected on lines W1 and W2;

=const; при ОЗЗ в точке 4 линии w1 (ϕ_0(м.ч)=0°, 10°, 20°, …, 90°) (векторная диаграмма (4, в); 3U₀=14,94+j1,307; 3I₀=0,0781+j0,443) и в точке 4 линии w2 модели (ϕ_0(м.ч)=-10°, -20°, …, -90°) (векторная диаграмма 4, б).in FIG. _Figure 4 shows the experimental dependences (4, a ) of the operation of the directional protection of the EPS from the OZZ modeled in the device, from the settings ϕ _{0 (m / h)} of the BMRZ-100 protection unit: P ₀ (S ₀ ) = f (ϕ _{0 (m / h)} ) at 3U ₀ , 3I ₀ ,

= const; with SCD at point 4 of the line w1 (ϕ _{0 (mph)} = 0 °, 10 °, 20 °, ..., 90 °) (vector diagram (4, c); 3U ₀ = 14.94 + j1.307; 3I ₀ = 0.0781 + j0.443) and at point 4 of the w2 line of the model (ϕ _{0 (mh)} = -10 °, -20 °, ..., -90 °) (vector diagram 4, b).

in FIG. Figure 5 shows the initial circuit - a) and equivalent circuitry of the forward (reverse) - b) and zero - c) sequences used in the computing element of the device. The circuit parameters in FIG. 5 are displayed in the following positions:

1, 2, 3, 4, 5 .. - numbers of elementary asymmetric sections modeled by equivalent circuits of lines W1 and W2;

1, c; 2, c; 3 in; 4, c; 5c; 6, 7, 8, .... 28, 29 - designation of passive longitudinal and transverse parameters of equivalent circuits of ES;

E _gl , E _g2 , E _m1 E _m2 , U _ij ^ns - EMF sources in equivalent circuits simulating the parameters of asymmetric modes;

in FIG. 6 shows the waveforms recorded by the oscilloscope of the protection unit in the preceding abnormal mode, and FIG. 6, and phase 3 (C) SCR mode at point 4 of line w1;

in FIG. 7 is a vector diagram of a protection unit corresponding to the waveform of FIG. 6, and for the time instant nT = 48 (t = 0.02);

in FIG. Fig. 8 shows the waveforms recorded by the oscilloscope of the protection unit in the preceding abnormal mode, and in Fig. 8a - to the phase 3 (C) SCR mode at point 2 of the w2 line;

in FIG. 9 is a vector diagram of a protection unit corresponding to the waveform of FIG. 8, and for the time instant nT = 48 (t = 0.02 s);

in FIG. 10 shows the predicted calculated values of the electrical quantities obtained by the computing element of the device and the corresponding vector diagrams, as well as the errors of the calculations based on the results of the simulation of the modes of OZZ performed in the example.

List of tables

Table 1, table 2, table 3, table 4 - numerical values of the equivalent circuit parameters; printouts of the results of calculations of the electrical quantities of the abnormal OZZ modes at switching point 4 on line w1 and on elements of the equivalent circuit at the installation site of the protection block at OZZ on lines w1 at point 4 and on line w2 at point 2, respectively.

Information sources

1. Rules for the installation of electrical installations. M. Energy Publishing. 2010.

2. Guidelines for the design of power supply systems up to 1 kV with isolated neutral at capital construction facilities of the Ministry of Defense. Approved 02/19/08. M.-SPb, 2008.

3. Schneerson E.M. Digital relay protection. M .: Energoatomizdat, 2007.

4. Digital block of relay protection type BMRZ-100. Manual. DIVG.648228.024 RE. 2013.

5. Losev S.B., Chernin A.B. Calculation of electrical quantities in asymmetric modes of electrical systems. M., Energoatomizdat, 1985.5.

6. Fedoseev A.M., Fedoseev M.A. Relay protection of electric power systems. M. Energoatomizdat. 1992.

7. Glukhov O.A., Mikhailov A.K., Fominich E.N. Insulation monitoring systems in power supply systems with insulated neutral. EMC technology. 2007. No3 (22).

8. Vladimirov Yu.F. Calculations of asymmetric modes as applied to the analysis of safety conditions in electrical installations. SPb .: VI (IT) VA MTO. 2014.

9. Vladimirov Yu.F., Fominich E.N. Mathematical modeling of the modes of electric networks with isolated neutral for predicting the behavior of digital protection and control devices. Military engineer. SPb. 2017, No 1 (3).

10. Report on research "Infinity." SPb .: VISI, 1996; No. 548904.

11. Vladimirov Yu.F. On the experimental determination of the parameters of the single-phase circuit mode on the physical model of the electric network line. SPb .: VITU, 1999, No. 559629.

Claims (1)

A device for modeling asymmetric modes and predicting the behavior of digital protections in electrical installations with isolated neutral, consisting of capacitive, resistive, inductive elements and switches that implement a complex three-phase electric circuit with concentrated parameters with two power sources in the form of transformers and a digital protection unit included in one from simulated lines, characterized in that the device includes a programmable element configured to calculate the electrical of the values of the modes of the virtual electric circuit with the topology and parameters adequate to the assembled physical model, the step of calculating the electrical values of the programmable element is chosen equal to the sampling period of the digital protection unit, the device is connected to the analog inputs of the digital protection unit, which is configured to switch to control and oscillograph parameters of the abnormal adjacent line mode; the device has an algorithm for comparing the values calculated in the programmable element, taking into account the switching moment, determined by the oscillogram of the tested digital protection unit, and the actual electrical values of the simulated abnormal mode, recorded by the oscilloscope of the digital protection unit, the device allows you to adjust the protection behavior by changing the response parameters according to the results of the comparison algorithm digital protection unit, as well as adjust the programmable element program, finishing Referring conditions for obtaining the required selectivity, sensitivity, and performance characteristics of protection.

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