RU2193812C2 - Device for on-line control of electrical energy supply and consumption in ac power mains - Google Patents

Abstract

FIELD: electrical engineering; electric measurements in ac circuits for metering power consumption and power supply in preset amount. SUBSTANCE: device has voltage and current measuring transducers connected to analog-to-digital converter, nonvolatile memory, radio control signal receiver, display unit, and controllable switch all connected to microprocessor unit. Device receives control commands incorporating address, command code, and data transmitted over broadcast radio channel, acquires limits on amount of electrical energy permitted for consumption, in definite time intervals reduces this limit by amount of electrical energy consumed within this period, and disconnects user's power circuit from supply mains as soon as preset limit is exhausted. EFFECT: enhanced efficiency of controlling power supply and consumption in municipal and district supply mains supplying each user with preset amount of electrical energy. 2 dwg

Description

 The invention relates to electrical engineering and can be used to measure the consumed electrical energy in two-wire AC circuits and for centralized monitoring of electricity consumption in a given amount.

 A known method of accounting for consumed electrical energy without limiting the quantity with measuring its value by a meter and subsequent payment according to accumulated readings (see. Minin V.P. Measurement of electricity. M .: Energy, 1974).

 The disadvantages of this method and devices that implement it are: the inability to supply electricity in a given amount; the impossibility of centralized remote shutdown and connection of the subscriber load circuit; the difficulty of monitoring the timing of payment of the cost of electricity consumed; low security of the result of measuring electrical energy in the event of intentional distortion.

 A known method of accounting for electric energy with advance or subsequent payment by recording information on the amount of electricity supplied to the carrier in the form of electronic cards, transferring information from the card to a meter that calculates the amount of electricity consumed and disconnects the subscriber load circuits or sets a power limit when consuming the released amount and devices for its implementation in the form of a counter containing voltage and current sensors connected to the multiplier a converter, the output of which is connected to the microprocessor, a random access memory device, a prepayment device and a directional button connected to the microprocessor, the output of which is connected to the display, and a switching device in the form of a vacuum switch, the control drive of which is connected to the microprocessor (RU, patent 2106644, cl. G 01 R 11/00, 1998; RU, patent 2098835, CL G 01 R 22/00, 1997).

 The disadvantages of this method of accounting for electricity and devices that implement it are: the impossibility of operational centralized control of the process of electricity consumption, disconnection and inclusion of load circuits of subscribers; the complexity of organizational and technical measures for entering information from cards; the requirement of certain skills and training from the subscriber when operating this device; low level of protection against unauthorized interference and forgery of cards.

 A known method of accounting for electricity with prepayment or subsequent payment and devices for its implementation, characterized in that the transmission of control signals and information on the consumed amount of electricity is carried out through a communication line, which is used as a telephone line or wires of an electric network (GB patent 2096370, cl. G 01 F 1/56, 1982; US Patent 5627759, CL G 01 R 19/165, 1997).

 The disadvantages of this method of electricity metering are: the high cost of the device and the infrastructure necessary for its implementation; low reliability of communication channels, the impossibility of broadcast control of a group of subscriber devices.

 The main task to which the invention is directed is to increase the efficiency of centralized remote control of the process of supplying and consuming electricity to subscribers of city and district electric networks, with the possibility of supplying electricity to each subscriber in a given quantity.

 In the proposed method, the problem is solved in that a broadcast radio channel is used as the operational control channel of the subscriber monitoring device, through which control commands are transmitted individually from the control center for each subscriber device and broadcast for groups or for all subscribers.

 System subscribers pre-purchase the required amount of electricity or order it on credit.

The minimum set required for control consists of the following commands:
- connecting the subscriber load circuit to the electric network;
- disconnection of the subscriber load circuit from the electric network;
- increase in the limit of electricity supplied.

 The command consists of the address of the subscriber unit, the command code and data on the amount of electricity supplied.

 Each subscriber unit in the system has one individual and several group addresses, receives commands transmitted over the air from the control center, recognizes the address, executes commands transmitted to its address, increases the limit of electricity supplied by the amount transmitted in the command, measures instantaneous voltage values and current in the load circuit, calculates the amount of electricity consumed for the time interval between measurements, subtracts it from the limit of electricity supplied. When reducing the remainder of the limit of electricity supplied to zero, the subscriber unit disconnects the load circuit from the electric network. Further inclusion of the load circuit is only possible upon receipt of a command to increase the limit of electricity supplied.

 Commands for disconnecting and turning on the load circuit are needed to solve the problems of network maintenance, for example, group disconnection of consumers in order to reduce the power consumption of the power system or to carry out repair and maintenance work.

 Due to the listed set of features, the proposed method provides greater efficiency, centralization, selectivity and flexibility of management, as well as more reliable and easy to implement than the known ones. In particular, since a radio channel is used as a control channel, it is possible to use both individual and group broadcast control without constructing special wired communication channels or data transmission channels superimposed on the electric network.

 The indicated advantages of the proposed method apply to the subscriber device for its implementation. In FIG. 1 shows a functional diagram of a subscriber device for monitoring the supply and consumption of electricity, shows its inclusion in the electric network.

 The device comprises a control command receiver 1, the output of which is connected to the input port of the microcontroller 6, a voltage measuring transducer 2, the input of which is connected in parallel to the load circuit 10, an output to an analog-to-digital converter 4, which is connected to the input port of the microcontroller 6, a load current measuring transducer 3, the output of which is connected to an analog-to-digital converter 5, which is connected to the input port of the microcontroller 6, a disconnecting device 9 of the load circuit, a control input cerned connected to an output port of the microcontroller 6, display unit 7 is controlled by the microcontroller 6 and the nonvolatile memory 8 connected to microcontroller 6.

 The receiver of control commands 1 through a magnetic or other antenna receives radio signals, filters them and converts them into digital signals suitable for processing by microcontroller 6.

 The voltage measuring transducer 2 contains a voltage sensor made in the form of a transformer connected by a primary winding parallel to the load circuit 9, and a secondary one to the input of a scaling amplifier that converts a signal proportional to the voltage in the load circuit to the measuring range of the analog-to-digital converter 4.

 The load current measuring transducer 3 contains a current sensor made in the form of a current transformer, the primary winding of which is one of the load circuit wires, and the secondary is connected to a scaling amplifier that converts a signal proportional to the load current to the measuring range of the analog-to-digital converter 5.

 Analog-to-digital converters 4, 5 can be separate or contained in the microcontroller 6 and convert analog signals proportional to voltage and current into a binary-digital code suitable for processing by the microcontroller 6.

 The display unit 7 contains an LED indicating the status of the device and a seven-segment liquid crystal ten-digit indicator showing the remaining limit of electricity supplied in kW • h with an accuracy of hundredths.

 Non-volatile memory 8 is necessary for storing data and tuning parameters during an emergency power outage, including the remainder of the limit of released electric power of the individual and group addresses of the device, the scaling factor and the interval between measurements.

 The disconnecting device 9 is made in the form of a high-current relay and is controlled by a signal from the microcontroller port 6. To reduce the dimensions, increase reliability and reduce the requirements for the electrical characteristics of the relay, disconnection occurs when the instantaneous value of the load current passes through zero, and when the instantaneous voltage value switches on through zero.

 The microcontroller 6 runs under the control of a special microprogram, cyclically, at fixed intervals, receives 4.5 digitized signals of instantaneous voltage and current from analog-to-digital converters, calculates the amount of electricity consumed for the time interval between measurements, subtracts this amount from the remaining limit of the released electricity, if the remainder of the limit has decreased to zero, it generates a shutdown signal, writes the remainder to the non-volatile memory 8 and displays it in digital form in Lok display 7, based on a command from the receiver control commands 1, recognizes the address, decodes and executes a command that increases the limit of supplied power to a value transmitted in a command, controls the disconnection device 9.

The block diagram of the microcontroller operation algorithm is shown in FIG. 2 and is as follows:
in block 1, the microcontroller is initialized and individual and group e-mail addresses are read from non-volatile memory, the remainder of the limit of electricity supplied, the time interval between measurements, the scaling factor for calculating the energy consumed over the time interval;
in block 2, the presence of the command received from the radio signal receiver is checked, if the address in the command matches one of its own addresses, block 10 is executed, otherwise block 3;
in block 3, the internal timer of the microcontroller is checked, if the time interval between measurements has passed, block 4 is executed, otherwise, return to block 2;
in block 4, digitized signals proportional to the instantaneous value of current and voltage measured in the load circuit are read from analog-to-digital converters;
in block 5, the remaining limit of supplied electricity is reduced by the amount consumed during the time interval between the measurements of electricity, calculated by multiplying the signals proportional to the instantaneous values of voltage and current, the value of the time interval between measurements and the scaling factor;
in block 6, the remainder of the limit of electricity supplied is recorded in non-volatile memory and displayed on the indicator;
in block 7, the balance of the limit of electricity supplied is checked, if it is greater than zero and the shutdown state is not set by command from the control center, block 8 is executed, otherwise block 9;
in block 8, at the control output of the disconnecting device, a load circuit enable signal is supported;
in block 9, at the control output of the disconnecting device, a load circuit trip signal is supported;
in block 10, the command code is checked, if it is a command to increase the limit of electricity supplied, block 11 is executed, otherwise block 12;
in block 11, the remainder of the limit of supplied electricity is increased by the amount transmitted in the team;
in block 12, the command code is checked, if it is a load circuit disconnection command, block 13 is executed, otherwise block 14;
in block 13, the shutdown state is set upon command from the control center;
in block 14, the command code is checked, if it is a load circuit switching command, block 15 is executed, otherwise block 2;
in block 15, the trip state is removed by command from the control center.

 The time interval between measurements of instantaneous values of current and load voltage is selected taking into account the performance of the microcontroller as small as possible, in order to reduce the total error in calculating the consumed electricity in order to provide 50-100 measurements for an alternating current period of 50 Hz.

 Due to the listed set of features, the proposed subscriber device for supplying and metering electricity provides greater efficiency, centralization and control flexibility than the known ones and can be used instead of an electricity meter in city and district electric networks. Using the proposed method and device will solve the problem of non-payments in the power supply systems of the civilian population and enterprises, as well as stop the practice of "blackouts", which, along with non-payers, conscientious subscribers suffer from.

Claims (1)

 A device for centralized operational control of the process of supply and consumption of electrical energy in AC networks, containing voltage and current transducers connected to analog converters, the outputs of which are connected to a microcontroller, non-volatile memory, an indication unit, a disconnecting device connected to a microcontroller, characterized in that control commands containing the address of the subscriber unit, command code and data on the amount of released energy transmitted received via the broadcast radio channel, they enter the control command receiver connected to the microcontroller, which recognizes the commands sent to it, reduces the limit of supplied energy by the amount of electricity consumed, calculated for the time interval between measurements of the instantaneous values of the load voltage and current, disconnects the load circuit when reducing the remaining limit of electricity supplied to zero, executes the accepted commands to increase the limit of electricity supplied, turning the heating circuit on and off zki.

Images