RU2605043C2 - Ermakov-gorobets data recorder for energy audit performance - Google Patents

Abstract

FIELD: computer engineering.

SUBSTANCE: invention relates to information-measurement and computer equipment and intended for calculation and indication of power loss averaged values, mains voltage and load current, and also can be used as recorder of these values for long period. Recorder comprises current sensor (CS) 1, mains voltage sensor (VS) 2, first 3 and second 4 input converters (IC), microcontroller (MC) 5, ambient temperature sensor 6 (ATS), conductor temperature sensor 7 (CTS), rectangular pulses generator 8 (RPG), third 9, first 10 and second 11 transceivers, digital indicator 12, read-only memory (ROM) 13, computer 14.

EFFECT: technical result is enabling possibility of continuous monitoring and recording of power loss, mains voltage and load current averaged values.

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Description

The present invention relates to the field of information-measuring and computer technology, is intended to calculate and display the average values of power losses, mains voltage and load current, and may also find application as a recorder of these values over a long period.

An analogue of the proposed recorder is an electricity loss counter [1], containing a computer, current sensor, analog-to-digital converter, functional converter, indicator, square-wave pulse generator, timer, timer-clock, accumulating adder, division unit, read-only memory, transceiver, first and second counters, first and second single vibrators.

The disadvantages of the analogue are the low accuracy due to the neglect of the dependence of the active resistance of current-carrying elements of electrical equipment on the heating temperature (the error for this reason can reach 40% [2]), as well as narrow functionality.

The closest technical solution to the proposed registrar is a power loss meter with indication of power losses (options) [3], containing a current sensor, a microcontroller, a register, a digital indicator, sensors of ambient temperature and electrical equipment, a rectangular pulse generator, the first and second transceivers, constant storage device, computer.

The disadvantage of the prototype is the narrow functionality.

The technical problem solved by the invention is the expansion of the registrar's functionality due to the possibility of continuous monitoring and recording of average values of power losses, network voltage and load current.

The specified technical problem is solved due to the fact that the energy loss counter with an indication of power losses (options) contains a current sensor, an ambient temperature sensor, a temperature sensor for a conductor, a rectangular pulse generator, a digital indicator, the first and second transceivers, read-only memory, a computer , a microcontroller, port C is connected to the output of the ambient temperature sensor, port D is connected to the output of the conductor temperature sensor, and the clock input is connected to the output to the square-wave generator, the outputs of the ports of the microcontroller are connected respectively F - through the first transceiver with the input of the read-only memory device, G - through the second transceiver with the input of the computer, an additional voltage sensor, the first and second input converters, the third transceiver through which the output of port E the microcontroller is connected to the input of a digital indicator so that the third transceiver is configured to record from the output of port E of the microcontroller and a digital indicator to display them per minute averaged value of the load current I _{1min, 1min} voltage U and power loss ΔP _1min, current sensors and voltage outputs are respectively connected via first and second input transducers with ports A and B of the microcontroller; the first and second input converters are identical, in particular, the first input converter contains a half-wave precision amplifier and a buffer scale amplifier, the input of which is connected to the input of the first input converter, and the output through a half-wave precision amplifier is connected to the output of the first input converter.

Significant differences of the proposed registrar are the introduction of additional elements (network voltage sensor, first and second input converters, third transceiver), as well as the organization of its new structure and the introduction of new connections between the elements. The combination of elements and the relationships between them provide a positive effect - expanding the functionality of the device due to the possibility of continuous monitoring and recording the average values of power losses, network voltage and load current.

The recorder circuit is shown in figure 1; figure 2 presents one of the possible options for implementing the input converter circuit.

The recorder circuit (Fig. 1) contains a current sensor (DT) 1, a network voltage sensor (DN) 2, the first 3 and second 4 input converters (VP), a microcontroller (MK) 5, an ambient temperature sensor (DTOS) 6, a sensor 7 conductor temperature (DTP), 8 rectangular pulse generator (GUI), third 9, first 10 and second 11 transceivers, digital indicator 12, read-only memory (ROM) 13, computer 14. The outputs of the current sensors 1 and 2 are connected respectively through first 3 and second 4 input converters with ports A and B of the microcontroller 5, port C of which is connected to the output of the ambient temperature sensor 6, port D is connected to the output of the conductor temperature sensor 7, and the clock input is connected to the output of the generator 8 of rectangular pulses, the outputs of the ports of the microcontroller are connected respectively E - through the third transceiver 9 with the input of a digital indicator 12, F through the first transceiver 10 with the input of the read-only memory 13, G through the second transceiver 11 with the input of the computer 14.

The first 3 and second 4 input converters have identical circuits, in particular, the first input converter 3 (Fig. 2) contains a half-wave precision amplifier (DNU) 15 and a buffer scale amplifier (BMU) 16, the input of which is connected to the input of input converter 3, and the output through a half-wave precision amplifier 15 is connected to the output of the input Converter 4.

The schemes of the buffer scale amplifier 16 and the half-wave precision amplifier 15 are well known, in particular, the circuits described in [4, 5] and shown in Figures 1.3 and 2.49 [4], 13.7, and 52.15 [5] can be used as their implementations.

The registrar (figure 1) works as follows.

The output voltage of DT 1, proportional to the load current I (t), is fed through the first input converter 3 to the input of port A of the microcontroller 5.

The current sensor 1 may, in particular, be made on a measuring shunt included in the secondary circuit of the measuring current transformer; it provides a low level output signal (nominal value 75 mV). To match the signal level of DT 1 with the operating range of the analog-to-digital converter (ADC) built into MK 5, the VP 3 uses a buffer scale amplifier 16 (Fig. 2), which has a large input impedance and a large gain of 15-80 (selectable depending on modifications used MK 5). VP 3 also employs a half-wave precision amplifier 15 to convert the bipolar sinusoidal signal DT 1 to unipolar.

The voltage sensor 2 can, in particular, be made on a measuring low-voltage step-down transformer (whose rated primary voltage is 100-220 V), connected to the secondary winding of a high-voltage measuring transformer (whose rated primary voltage is 6-220 kV) or connected directly to 220 V network (when monitoring parameters in a low-voltage network); it provides an output signal of a level of several volts (the signal level depends on the standard parameters of the used low-voltage step-down transformer and the voltage level of the controlled network). To match the signal level DN 2 with the operating range of the built-in ADC in the MK 5 ADC in VP 4 is used BMU 16 (figure 2), having a large input impedance and a small gain of 0.5-5.

The control program with a sufficiently high speed alternately connects the output signals of the sensors 1-2 to the input of the ADC MK 5 in such a way as to obtain digital codes of the load current and network voltage 50-100 times per period. These codes are squared, and the sum of the squares accumulate in two cells for 1 min.

As you know, power losses in current-carrying elements (FC) are determined by the formula

ΔP = I ₂ R, (1)

where I (t) - time-varying load current flowing along the FC;

R is the resistance of the fuel cell.

In simplified calculations, the resistance R is assumed to be constant over time and equal to the resistance R ₀ at an ambient temperature of Θ ₀ = 20 ° C or resistance at another fixed temperature.

The exact value of the resistance R as a function of temperature Θ _TE FC is determined by the formula

R = R ₀ + αR ₀ (Θ _FC - ₀ ), (2)

where α is the temperature coefficient of resistance of TE; it matters for copper α _m = 0.0041 ° C ^-1 , aluminum α _a = 0.0044 ° C ^-1 , steel α _article = 0.006 ° C ^-1 .

If there is access to the fuel cell, its temperature Θ is determined using the temperature sensor 7 of the connection conductor, the resistance R of the conductor is calculated in MK 5 by the formula (2), and the loss value ΔР is determined by the formula (1).

Management of the registrar is as follows.

At the same time intervals ΔТ = 1 min, the transceiver 9 from the output of port E MK 5 in DI 12 records the load current averaged per minute I _1min , mains voltage U _1min and power losses ΔP _1min , which are subsequently displayed on digital indicator 12, continuously updated every minute.

The transceiver 10 once per hour places in the next cells of the ROM 13: date; hour; load current values I _{1 hour} , network voltage U _{1 hour} , power loss ΔP _{1 hour} (numerically coinciding with the loss of electricity for this hour), etc.

In the event that there is no access to the connection conductor (for example, to the cable conductors on which the accident was not installed when laying the cable), sensor 6 measures the ambient temperature Θ _okr once a minute, and the temperature of the conductor Θ is determined from the differential heating equation according to the following formula [6]:

$$\tau \cdot \frac{d\Theta }{dt}+\Theta =K_R\cdot \left({\Theta }_{n\mathrm{about}mi}-{\Theta }_0\right)\cdot \left[\frac{I_i^2}{I_{n\mathrm{about}mi}^2}\right]+{\Theta }_{\mathrm{about}\mathrm{to}R},\text{(3)}$$

- коэффициент изменения сопротивления проводника в функции от температуры;Where $$K_R\left(\Theta \right)=\frac{\mathrm{one}}{\mathrm{one}+\alpha \left({\Theta }_{n\mathrm{about}m}-{\Theta }_0\right)}\left[\mathrm{one}+\alpha \left(\Theta -{\Theta }_0\right)\right]$$

- coefficient of variation of the resistance of the conductor as a function of temperature;

Θ _nom - nominal long-term permissible temperature of the conductor;

I _nom - rated current of the conductor;

I is the rms value of the load current.

The advantage of the invention in comparison with the known analogues are wider functionality. The recorder circuit is focused on the use of a modern microelectronic basis - microcontrollers.

Information sources

1. RF patent 2380715, IPC G06F 17/18, 2008.

2. Osipov D.S. Accounting for heating of live parts in the calculations of power and electricity losses in non-sinusoidal modes of power supply systems: Abstract. dis. ... cand. tech. sciences. - Omsk, 2005.

3. RF patent 2449356, IPC G06F 17/18, 2012, 5 independent claim (prototype).

4. Application of integrated circuits: a practical guide. In 2 book Per. from English / P. Bradshaw, S. Ghosh, X. Aldridge and others; Ed. A. Williams. - M .: Mir, 1987. Book. 1 .-- 432 s.

5. Count R. Electronic circuits: 1300 examples. Per. from English - M .: Mir, 1989 .-- 688 p.

6. Gudzovskaya V.A., Ermakov V.F., Balykin E.S., Zaitseva I.V. A mathematical model of the process of changing the heating temperature of a conductor // Izv. universities. Electromechanics. - 2012. - No. 2. - S. 42-43.

Claims (2)

1. A data logger for conducting an energy audit, comprising a current sensor, an ambient temperature sensor, a conductor temperature sensor, a rectangular pulse generator, a digital indicator, the first and second transceivers, read-only memory, a computer, a microcontroller, the port of which is connected to the output of the ambient temperature sensor environment, port D is connected to the output of the temperature sensor of the conductor, and the clock input is connected to the output of the rectangular pulse generator, the outputs of the ports of the microcontroller are connected respectively, F - through the first transceiver with the input of the read-only memory device, G - through the second transceiver with the input of the computer, characterized in that it additionally includes a voltage sensor, the first and second input converters, the third transceiver, through which the output of port E of the microcontroller is connected with the input of a digital indicator so that the third transceiver is configured to record from the output of port E of the microcontroller in a digital indicator to display them averaged e per minute value of the load current I _{1min, 1min} voltage U and power loss ΔP _1min, current sensors and voltage outputs are respectively connected via first and second input transducers with ports A and B of the microcontroller. 2. The registrar according to claim 1, characterized in that the first and second input converters are identical, the first input converter comprising a half-wave precision amplifier and a buffer scale amplifier, the input of which is connected to the input of the first input converter, and the output is connected to the output through a half-wave precision amplifier first input converter.

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