RU2456623C1 - Device for active energy electric metres verification - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: proposed is a device for verification of inductive active energy electric metres which contains an operating capacitor charged from the electric mains via a HF commutator and discharged immediately back into the mains; the capacitor capacity is selected based on power consumed as unaccounted. One of the operating capacitor poles is connected to the electric mains phase and neutral conductors via alternatively controlled power transistors, the other pole connected via alternatively commutating bidirectional thyristors parallel whereto filtering capacitors are joined up. Two additional commutating bidirectional thyristors are used in the operating capacitor discharge circuits, alternating activation of all the power transistors and bidirectional thyristors is performed by the control unit connected to them, such control unit operation synchronised by the electric mains signal.

EFFECT: evaluation of active energy electric metre protection against eventual uncontrolled electric energy stealing.

2 dwg

Description

 The invention relates to electrical engineering and can be used in the development of electric meters of active energy.

The total electricity consumption in 2010 was about one trillion kWh. Statistical analysis showed that at least 10 percent of the energy generated and supplied to users is stolen by them, which amounts to commercial losses. There are various ways to combat the theft of electricity by household consumers [1-2] in rural areas, suburban homes and horticulture by transferring phase and zero input conductors connected to the branch from the OHL - 0.4 kV, and using a hidden grounding device. These methods create savings of at least 30 billion rubles annually. The industry has developed new electric meters with two current measuring circuits (for example, type CE-200), the use of which is insensitive to the indicated transfer of input conductors. Such electricity meters are installed in cities and in new buildings. However, the operation of such electric meters can be disrupted by the use of simple electrical circuits [3-4], designed to test the current sensitivity of electric meters, using a hidden grounding device. This will further increase the theft of electricity, especially in connection with the constant increase in tariffs for it.

The measures taken to counter theft of electricity taken by the Gostekhnadzor and local energy sales departments are insufficient, and the growth trend of theft of electricity requires, in addition to strengthening the control functions of creating electricity metering devices of a fundamentally different design [5], which leads, in particular, to the abandonment of the use of induction current meters in them , since electronic circuits have been developed for stopping or slowing down the operation of induction metering devices that do not require the use of hidden emlyayuschego device, wherein filling of permanently attached and the meter integrity element is not broken by consumers. Such devices are completely self-contained and simply plug into an electrical outlet.

To check the operation of a new type of electric meters, including induction type electric meters, which are equipped with 100% of domestic consumers in the country, it is necessary to develop a simulator device. The claimed technical solution is devoted to the solution of this problem. By varying the parameters of it, one can determine the degree of vulnerability of existing and newly developed electricity meters.

The aim of the invention is to assess the security of active energy meters from the possibility of uncontrolled theft.

This goal is achieved in the inventive device for checking electric meters of active energy of an induction type, containing a working capacitor charged from the electric network through a high-frequency switch and discharged back to the network directly, the capacity of which is selected based on unaccounted-for power consumption, characterized in that the working capacitor is one of its poles connected to the phase and neutral conductors of the electrical network through alternately controlled power transistors, and to others through commuting transistors enno triacs, which are incorporated in parallel filtering capacitors, in addition, the bit circuits operating capacitor used two complementary switching of the triac, and alternately switch all power transistors and triacs effected connected thereto a control unit whose operation is synchronized electrical network signal.

The achievement of the objective of the invention is explained by the reduction of electricity metering by an induction meter in odd quarters of the mains voltage periods with the appropriate selection of the frequency in the high-frequency pulse generator, quickly interrupting the charging current in the working capacitor, and by returning the stored electric power from it without modulating the discharge current, which either stops the operation meter, or reduces its readings depending on the magnitude of the connected load and on the value of the capacitance of the working capacitor.

The invention is clear from the presented drawings.

Figure 1 shows the electrical circuit of the charge-discharge circuit of the working capacitor under control from the control unit, consisting of:

BU - control unit,

T ₁ and T ₂ - the first and second power transistors of the charge circuits,

With ₁ - working capacitor that determines the energy of the device,

D ₁ ... D ₄ - triacs of charging and discharge circuits of the working capacitor C ₁ ,

C ₂ and C ₃ - filtering capacitors installed parallel to the triacs of the charging circuits of the working capacitor.

The conclusions of the control unit connected to the network, and the associated conclusions of the control circuits of power transistors and triacs are indicated by numbers from 1 to 8.

Fig. 2 shows the functional diagram of the control unit BU (Fig. 1), containing a phase-shifting circuit of two capacitors C and resistors R, one of which is adjustable, providing a phase shift of the input AC voltage by π / 2, two limiting amplifiers, two inverter, six coincidence circuits, a high-frequency pulse generator (VIM) with an adjustable pulse repetition rate, six isolation capacitors and six current switches used to alternately open-lock power transistors and ditch in the diagram in Fig. 1. This diagram does not show separate power supplies of current keys with their common output points 4 and 5, as well as the power supply of TIGs, limiting amplifiers made on operational amplifiers, and logic elements - inverters and matching circuits, for example, on TTL logic . These power supplies are connected to mains voltage. Each of a pair of series-connected RC circuits creates a phase shift of the input voltage by 45 °. Adjusting the resistor in one of them allows you to specify the complete phase shift by 90 °. In this case, the signal u (t) ₁ = ηU ₀ sin2πFt acts on the input of the first amplifier-limiter, and the signal u (t) ₂ = ηU ₀ cos2πFt, where U ₀ and F is the amplitude and frequency of the mains voltage, η <<1 - division coefficient of the mains voltage (the active divider of the mains voltage is not shown in the diagram). A micropower step-down transformer can be used as a divider.

Consider the action of the claimed device.

It operates in four cyclically repeating stages, the total duration of which is equal to the period of the mains voltage T.

At the first stage, 0≤t≤T / 4, the working capacitor C ₁ is charged through the circuit "first power transistor T ₁ - triac D ₄ ". In this case, the triac D _{4 is} opened by a signal from terminal 8 from the output of the control unit, and the power transistor T ₁ interrupts the charge circuit with a high-frequency signal of a particular frequency f coming from terminal 1 of the control unit. Modulation of the charge current leads to a reduced metering of the energy consumed by the working capacitor due to the properties of the induction measuring current circuit of the active energy meter. On operating the capacitor formed by the charge with the energy W = C U ₀ ² _1/2 where U ₀ - amplitude value of the supply voltage equal 310B at an effective voltage of 220 V. The analysis shows that by using a high-frequency modulation of the charging current signal energy electricity meter accounting W makes up only 20 ... 30% of this value depending on the selected value of the frequency of interruptions of the charging current, determined by the operation of the high-frequency pulse generator 9 (Fig. 2). Note that the parallel connection of the filter capacitor C ₃ to the triac D ₄ leads to the maintenance of this triac open at the stage of charging the working capacitor C ₁ .

In the second stage, T / 4≤t≤T / 2, the working capacitor C _{1 is} discharged along the circuit "triac D ₁ - triac D ₄ ". At the same time, the previously opened first power transistor T ₁ is closed. In this case, the control signal from terminal 8 of the control unit, the duration of which is T / 2, continues to act on the triac D ₄ , and the control signal from terminal 2 of the control unit of T / 4 duration continues to operate on the triac D ₁ . The charge energy W is transferred back to the network, and at the same time, the induction meter for electricity metering is working properly, at 100%, since the discharge current is not modulated by high-frequency pulses with TIG.

At the third stage T / 2≤t≤3T / 4, the working capacitor C _{1 is} again charged through the circuit "second power transistor T ₂ - triac D ₂ " in the second half-wave of the mains voltage period. The charge current is also interrupted due to its modulation by a TIG signal, which leads to incorrect metering of the energy W by the electric meter. The control signal to the power transistor T ₂ comes from terminal 6 of the control unit. Triac D ₂ acts on the control signal from pin 3 of the control unit. The filter capacitor C ₂ , connected in parallel with the triac D ₂ , performs the same functions as the filter capacitor C ₃ .

In the fourth stage, 3T / 4≤t≤T, the working capacitor C _{1 is} discharged through fully open triacs D ₂ and D ₃ . The control inputs of these triacs are affected by control signals, respectively, from pins 3 and 7 of the control unit. In this case, the second power transistor T _{2 is} closed.

Separating capacitors Cp transfer from the logic circuits for generating control signals a variable component of logical zeros and ones, but they separate the current keys from the logic circuit by constant components, since the low-voltage power supplies of the device logic circuit are grounded, and two separate ungrounded power supplies of six current keys are “suspended” relative to grounding (neutral conductor network). In this case, the current switches forming the terminals 1, 2, 6 and 7 of the control unit have a common point of their power source with terminal 4 of the control unit, and the current switches with terminals 2 and 7 have a common point of their other power source with terminal 5 of the control unit.

Current switches generate control signals for switching on power transistors and triacs (Fig. 1) of the required power, depending on the types of power transistors T ₁ and T ₂ and triac D ₁ ... D ₄ , as well as depending on the power switched by them, determined by the working capacity capacitor C ₁ .

A high-frequency pulse generator (TIG) contains a frequency-tunable RC generator and a TTL-pulse generator in the form of a “meander”, which are modulated by TTL-pulses of duration T / 4, corresponding to the first and third quarters in each period, for example, in the frequency range 1 ... 20 kHz mains voltage.

In subsequent periods, the processes of charge and discharge of the working capacitor C _{1 are} repeated with a frequency of 2F, where F is the frequency of the mains voltage (F = 50 Hz).

If the frequency of interruptions of the charge f >> F is chosen so that the energy accounting for the charge is, for example, 0.25 W, and the retroactive accounting is equal to W, then the power of the electricity back-counting by such an accounting device will be P = 0.75 W F.

Consider an example. Let C ₁ = 500 μF, F = 50 Hz, U ₀ = 310 V. Then the power of the electricity back-counting will be P = 0.75 * 5 * 10 ^-4 * 310 ² * 50 = 1802 W. The working capacitor C ₁ must be designed for an operating voltage of 400 V and allow operation in the frequency mode of the charge. The frequency f of the high-frequency pulse generator 9 is of the order of 1 kHz to 20 kHz and is selected depending on the design of the induction current measuring circuit of the electric meter according to the maximum power P. The filter capacitors C ₂ and C ₃ are selected to be less than the capacitance C _{1 by} a factor of k times ratio f / F. If f = 10 kHz, k = 3, then C ₂ = C ₃ = 3 * 500 * 50/10000 = 7.5 μF. These capacitors also count on an operating voltage of 400 V, and they must allow operation in the frequency mode (at f = 10 ... 20 kHz).

The implementation of this device only on controlled triacs is undesirable, since high-current triacs operate reliably only in the low-frequency range. Therefore, it was decided to use npn type transistors with a reverse voltage on the collector of at least 800 V as the high-frequency pulses controlled by the charging circuit commutators. Since the power transistors and triacs operate in the key mode, the power dissipation on them is small even at high power values P [ 6-8]. Given that the charge of the working capacitor C _{1 is} unipolar (without overcharging), small-sized electrolytic (tantalum) capacitors can be used. This significantly reduces the weight and dimensions of the device.

It is advisable to dispense with induction meters of active energy in the future and use total energy meters (active and reactive).

Literature

1. Smaller O.F. The method of combating theft of electricity, RF patent No. 2208795, publ. in bull. No. 20 dated 07/20/2003.

2. Smaller O.F. The way to combat the theft of electricity (Lesser method), RF patent No. 2308726, publ. in bull. No. 29 dated 10/20/2007.

3. Smaller O.F. A device for checking the sensitivity of an electronic electric meter with two current circuits with active load and reactive compensation № publ. in bull. No. 31 dated November 10, 2008.

4. Smaller O.F. A method of verifying the operability of an electronic electricity meter with two current measuring circuits and a scheme for its implementation, RF patent No. 2344428, publ. in bull. No. 02 dated January 20, 2009.

5. Zhezhelenko I.V. Electricity quality indicators and their control at industrial enterprises, - 2nd ed., M., Energoatomizdat, 1986.

6. Blikher A. Physics of thyristors, trans. from English., L., 1981;

7. Evseev Yu.A., Dermenzhi P.G. Power semiconductor devices, M., 1981.

8. Tuchkevich V.M., Grekhov I.V. New principles for switching high power semiconductor devices. L., 1988.

Claims (1)

A device for checking electric meters of active energy of an induction type, containing a working capacitor charged from the electric network through a high-frequency switch and discharged directly into the network, the capacity of which is selected based on the powerless consumption, characterized in that the working capacitor is connected to the phase and zero poles by one of its poles electrical conductors through alternately controlled power transistors, and others through alternating switching transistors, parallel to which on cheny filter capacitors, in addition, the bit circuits operating capacitor used two complementary switching of the triac, and alternately switch all power transistors and triacs effected connected thereto a control unit whose operation is synchronized electrical network signal.

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