RU1780022C - Method for monitoring electric energy consumption - Google Patents

Abstract

Usage: in electrical engineering, in systems for controlling the consumption of electricity and control modes of power consumption of the enterprise. SUMMARY OF THE INVENTION: when monitoring energy consumption, the energy consumption is periodically measured from the beginning of the monitoring time interval, the time between pulses is measured and the current power is determined, then the average power is determined from the beginning of the monitoring period until the next pulse arrives from the pulse meter of the electric meter , determine the predicted value of electricity consumption for the control time interval, in excess of its predetermined allowable value of energy consumption and detuning from peak short-term loads, a control pulse is generated to turn off the consumers of electricity. 2 ill.

Description

The invention relates to electrical measurement technology and can be used in systems for monitoring the consumption of electricity and controlling the power consumption of the enterprise.

The aim of the invention is to increase the accuracy of monitoring by determining the current power in time between pulses from the meter-sensors of electricity consumption, taking into account the rate of change of load and timely decision to limit the load.

In FIG. 1 shows a structural diagram of a device that implements the proposed method, FIG. 2 are graphs illustrating the method.

The goal is achieved in that during periodic measurement of the parameter

iti -1 -t-Pi -i (Ti -ti -i) -b

cpi

Pcpi-power consumption measure the time between pulses from a meter-sensor of electricity and determine the current power by the formula

Xj

(1)

Atr

00

where KI is the transformation coefficient of the current transformer;

K2 - transformation ratio

voltage transformer;

C is the price of the output pulse of the pulse meter of the electric meter, kWh / imp;

Ati ti-ti-i - the length of time between the i-M and (i-1) -M pulses of the sensor.

From the beginning of the monitoring period T (min) for each i-ro measurement, the average power is calculated

i-Pi-i) (ti-ti-i)

Pcpi - itl - 1 + PI - 1 (ti tl - l) + (tl - ti - I / tg (p

 2 Pcpi - 1 + PI - 1 (tl - tl - i) + (tl - ti - 1) 2, g y

2ti

where Pcpi - 1 average power for ti-i time, for Pcpi -

Pi, Pi-1 - current power, respectively, for the i-th and (1-1) -th measurements;

ti, ti-i - time from the beginning of the control interval, respectively, to i-ro and (i-l) -ro measurements:

Pi-Pi-1 ,,

Щ 10 V - measuring speed ti - 1

no current power.

Then, the predicted value of power consumption for a reference time interval is calculated.

 Pcpi - iti - 1 -f Pi - 1 (T - ti - l) +

W

prog |

ti-i) (Pi-Pi-l)

Pcpi - lti - 1 + 2 (ti -ti -1), 2

, (T -,: .-, - U-i: fjfi2i

(3)

in the particular case when, i.e. ,

WnporHi Pcpiti-KT-tl) Pi. (4)

The predicted value of electricity for any i-ro metering is formed under the assumption that the rate of change of the current power for the last metering period (ti-ti-i) remains constant until the time T,

Further, WnporH is compared with a predetermined allowable value of power consumption for a control time interval (Ws)

(5)

 P ,.

where Rmax is the value of the maximum power consumption specified by the power supply organization.

When the condition

(6

 Wa

Wi

prog |

And checking the limit on the limiting value of the rate of change of the current power (Forerunner). if U Prev. fulfills (2)

with power outages.

Limitations on the limiting value of the rate of change of the current power are fulfilled in connection with the detuning from short-term peak loads arising from the startup of large power consumers, the operation of power consumers with short-term rapidly changing loads. In these

In cases under the condition WnporH W3, there is a delay in disconnecting the load for a time sufficient to reduce the rate of change of the current power to acceptable values. When the acceptable rate of change of the current power is reached and the condition WnporH Ws is maintained, the load is limited.

A device that implements the proposed method for controlling energy consumption comprises a microcomputer unit 1, a pairing unit 2, a timer 3, a control panel 4, an indication unit 5, an output unit 6, a power consumption counter 7.

The values entered in the RAM of the microcomputer

time intervals for the passage of the maximum active power in the power system, the maximum power value specified by the energy supplying organization, transformation coefficients Ki, K2, price

the output pulse of the counter-sensor, the parameter Prev, the duration of the control time interval T.

The device operates as follows.

At the time to, determined by the beginning of the passage time of the maximum, the pulses from the electric meter-sensor 7 through the pairing unit 2 enter the microcomputer using timer 3 according to the formula (1)

the current power and average power are calculated by the formula (2). Then, using the formula (3), the predicted energy consumption value is calculated, which is compared with the predetermined value Wa. The set value of power consumption is calculated by the formula (5). Under the condition of Wnpoi-H W3 and Y Prev, time for decision unit 5 or for automatic control by load reduction (T-ti) is displayed on the ind / 1 cation block. The output unit b receives a signal from disconnecting the first load stage.

Under the condition of V Uprd and WnporH W3, there is a delay in disconnecting the load for a time during which the rate of change of the current power becomes lower than Prev. Using the control panel 4, the parameters are entered into the microcomputer and the program is controlled.

The proposed method allows controlling the energy consumption taking into account the rate of change of load, provides timely decision making on load control with sufficient accuracy of current power measurement.

The calculation of the current power in the traditional way by counting the number of pulses from the counter-sensor for time intervals equal to 2. 5, 10 min according to the formula

nt c

(7)

Pi

where g is the duration of the measurement, taken equal to 2, 5, 10 min:

nt is the number of pulses received from the counter-sensor during time t;

C is the price of one pulse, kWh / imp. has an error D P, the value of which is determined by the price of the pulse, and this error is greater, the greater the price of the pulse. This is because the moments of pulse formation and Pi power measurements during load averaging over 2.5.10 minutes do not coincide in time. With large values of the transformation coefficient of measuring current transformers Kt and the voltage coefficient of Kn, the error can reach significant values.

For example, it is necessary to take into account the electricity consumption for commissioning 10 kV (Kt 2000/5 400, KN 10000/100 100). The maximum value of the error of the measurement channel corresponding to this input, as is known, is equal to the price of one pulse

400 100

 40 kWh / imp.

From 1000

where 1000 is the number of revolutions of the counter disk per 1 kWh of secondary energy in the measurement circuits.

In addition, when normalizing the pulse coefficient and reducing the error to half an hour or hour power m.

 2Jfc, P (1) ti - 1 -f Pi - 1 (tj - tij-jj + (ti -ti - l) Tgy

-cpi

the value of the error in determining the power increases significantly. (Trubnikov E.V. On undertaking current load monitoring using the IISE1-48 information-measuring system.

Industrial Energy, 1986, M 5. S. 26-27). Thus, with an averaging time of 2 minutes and bringing to hourly power, the error will be 40 60 / 2-1200 kW, which prevents the ability to provide the necessary level of regulation of power consumption. The current power measurement using the proposed method according to formula (1) does not have such a factor causing an error (in the book by V. Gordeeva. Regulation of the maximum load of industrial electric networks, - M .: Energoatomizdat, 1986, 184 pp. Shows the dependence of the error of load regulation on averaging period).

With regard to the accuracy of measuring current power at small intervals, especially in the field of high power, it should be noted that the accuracy of the primary measurement depends on the physical implementation of the electricity meter counter (induction or electronic meters with sensors) and the choice of measuring current transformers and

voltage, so that the method is implemented for a linear dependence in the range of small At values (up to 1 min).

Claims (1)

SUMMARY OF THE INVENTION A method for monitoring energy consumption, which consists in periodically measuring an electric power consumption from the beginning of a monitoring time interval, characterized in that, in order to increase the accuracy of monitoring, the time between pulses and determine the current power by the formula R.K1K,, where KI is the transformation coefficient of the current transformer; K2 is the transformation ratio of the voltage transformer; C is the price of the output pulse of the pulse meter of the electric meter, kWh / imp; At ti-ti-i is the length of time between the i-M and (i-l) -M pulses of the sensor, then the average power is determined from the beginning of the monitoring period T to the moment the next pulse arrives where Pcpi, Pcpi - 1 - average power, respectively, for ti and ti-i time; PI, PM - current power, respectively, for the i-th and (1-1) -th measurements of the pulse arrival time; ti, ti-1 - time from the beginning of the control interval, respectively, to i-ro and (j-l) -ro measurements; Pi-Pi-i tg rate of change tj ti - 1 current capacity; and determine the predicted value of electricity consumption for the control time interval T for 1st measurement WnporH Pcpi - iti - 1 + PI - l (T - ti - 1) +  (T -ti -ifigt a when the condition WnporH W3, where Ws is the specified allowable value of power consumption for the control time interval, and detuning from peak short-term loads, a control pulse is generated to turn off the consumers of electricity. Figs ti-l ti