SE515272C2 - System for controlling electrical power fed to outlet connected to mains - Google Patents

Abstract

A load monitor (14) monitors the current in the phases in a group central unit (16) connected to the mains and coupled to the control unit (10) in order to regulate the electrical power supplied to the outlet dependent on the actual load on the group phases, so that overload of the group central unit phase fuses is avoided. In the receiver unit (12) is a phase monitor connected with the mains (13). The phase monitor, by means of a grid component arranged on its outlets, synchronises an identification signal with the mains voltage phase position, so that a positive phase in the mains voltage permits control of a first electrical outlet and a negative phase in the mains voltage permits control of another electrical outlet. Information is transmitted from the control unit to the receiver units by means of frequency shift-keyed (FSK) modulated signals superimposed on the mains voltage.

Description

515 272 Furthermore, electrical outlets are generally secured with a fuse that is dimensioned against the phase fuse of a group center. To protect against overload on the phase fuse, the fuse of the electrical outlet is dimensioned lower than necessary, which is a disadvantage, as the system cannot be fully utilized.

An object of the present invention is to provide a system for controlling electrical power, which prevents overloading of the mains, while optimizing the performance of the system.

Another object is to provide a control system which is simpler and cheaper than known systems.

§MMNEAllNlN§ The above object is achieved by a system for controlling electrical power supplied to electrical outlets connected to an electrical network, which system comprises a central control unit, means for transmitting information between the control unit and the electrical outlets and a plurality between the electrical network and socket-connected receiver units, and a load monitor arranged to sense the current in resp. phase of a group control panel connected to the network and connected to the control unit to regulate it to resp. electrical outlets supplied with electrical power in dependence on the current load on resp. group phase, so that overloading of the group control panel phase fuses is avoided, which is characterized by a phase sensor arranged in the receiver and connected to the network, which phase sensor by means of gate means arranged on the phase sensor outputs synchronizes an identification signal with the mains voltage positive position control of a first electrical outlet and a negative phase of the mains voltage results in control of a second electrical outlet. 515 272 With this new control system, the investment cost will be significantly lower, as you can supplement existing electrical outlets with the system, and it will be much more difficult to "steal" electricity. There are also a number of additional functions, such as billing systems and control of the system via the telephone network.

In addition, the load monitors sense the load and control resp. electrical outlet as needed. In this way, you can increase the power output from each electrical outlet.

The system can be used in places where you have a number of electrical outlets for "rental", such as parking lots with engine heater outlets, campsites, caravan sites, etc.

Information is preferably transmitted from the control unit to the receiver units by means of FSK-modulated signals superimposed on the mains voltage.

The invention will be described in more detail by way of example, with reference to the accompanying drawing, in which: Fig. 1 is a block diagram of the control system according to the invention, Fig. 2 is a block diagram of a control unit included in the control system of Fig. 1; Fig. 3 is a block diagram of a receiver unit included in the control system of Fig. 1, and Fig. 4 is a block diagram of a load monitoring unit included in the control system of Fig. 1, the connection of a current transformer being shown in Fig. 4A. 515 272 Eög fi pßggug UTFQmugsEoRr / IER Hereinafter described preferred embodiments of the invention in the form of a system for controlling electrical power which is supplied to users of engine heater outlets in a parking space.

Fig. 1 shows the system according to the invention comprising a control unit 10, which via a cable 11 is connected to a meter exchange 18 between an input cable 19 and subsequent cables 13 in a 230V network. Furthermore, the system comprises a plurality of receiver units 12, which are also connected to the 230V network after group exchanges 16 of the network 13 and which control electrical outlets on the various network phases. Finally, the system comprises a load monitor 14, which is connected via lines 15 to the phase lines of the group exchanges 16. The control unit and the load monitor can be interconnected via a line 17, but information can also be transmitted via the 230V network 13, which will be described in more detail below.

The control unit 10, which is shown in more detail in Fig. 2, comprises a microprocessor 20 of conventional type, such as a processor from the family 8051. A number of conventional memory circuits 34, 36, 38 are connected to the processor, which contain programs, parameters, etc. for administering the signal transmission, and electronic circuits - an RF generator 80 and a power amplifier 82 - for generating a high-frequency, frequency-shift modulated (FSK-modulated) control signal, which is transmitted on the 230V network 13 via the connection 11. The processor can also be connected to the load monitor 14 via the line 17.

The control unit 10 also comprises a keypad 22, a number display 24 and indicators 26 for operating the system. In addition, there is a serial port 28 for connection to a parent control computer, e.g. a PC 30. 515 272 The control unit also comprises a power supply unit 39 connected to the 230V mains 13 for 5- and 35-volt supply.

The control unit 10 can either be used independently for control or controlled as a slave unit for the parent PC 30, which is used in cases where additional functions are to be connected to the system, e.g. telephone operation. With the parent PC, which can have a modem 32 connected, the system can be operated directly or remotely operated via the modem from a keypad telephone (not shown). Other peripheral devices, such as credit or debit card readers, etc., can also be connected to the PC.

The receiver units 12, one of which is shown in more detail in Fig. 3, are located in electrical outlet boxes in the parking lot. They comprise an FSK demodulator 56 connected to the input, which receives an FSK-modulated signal superimposed on one of the phases of the mains, demodulates this signal and supplies this demodulated signal to a pulse decoder 58. The output of this pulse decoder is via gate logic 62A, 62B of AND type connected to two time circuits 50A, 50B, which control a resp. relays 52A, 52B. The other inputs of the gate logic are connected to the output of a phase sensor 60, the input of which is connected to the 230V mains.

The receiver unit also has a code selection switch 64 connected to the pulse decoder for setting the current ID code and a power supply circuit 65 for supplying the electronics to 5V.

The system according to the invention utilizes digital signal transmission, in that it transmits digital information via ordinary mains voltage lines by means of a FSK-modulated high-frequency signal superimposed on the mains voltage. This control signal is suitably in the frequency range 125-140 kHz. 515 272 The signal transmission from the control unit 10 to the receiver units 12 takes place in such a way that for each electrical outlet 54A, 54B which is to be switched on, a number (5-7) of pulse trains are sent out from the control unit, which consist of an identification code (ID code ) for a resp. receiver unit 12. The time extension for such a pulse train is about 8 ms.

When the pulse decoding circuit 58 in a receiver unit 12 detects the correct ID code, which requires identification of at least 4 pulse trains, it emits a trigger pulse to resp. time circuit 50A, 5OB, which thereby controls its resp. relays 52A, 52B. This in turn turns on the voltage at a corresponding electrical outlet 54A, 54B. The timing circuit keeps the relay switched on for about 15 s, which is the system's normal cycle time, within which time period a new ID code must be received to keep the voltage to the electrical outlet continuously switched on. Although only a limited number of receiver units are shown in Fig. 1, up to approx. 100 pcs can be connected with the cycle time specified for the system in the following, 15 s. By extending the cycle time, the number can be further increased.

By synchronizing the control signals (pulse trains) with the phase sensor 60 by means of the phase position of the mains voltage, a demodulator and decoding circuit can be made to control two electricity consumers, in this case relays 52A, 52B, which control the measurement of electrical power from the mains to two electrical outlets 54A resp. 54B.

This is advantageous as each outlet box in a car park usually has just two electrical outlets.

To control (turn on) the first electrical outlet, 54A, the control signal is transmitted during the positive half period of the mains voltage and to control the second electrical outlet, 54B, transmission takes place during the negative half period. By means of the phase sensing device 60 for the phase of the mains voltage, by means of the gate elements 62A, 62B the trigger pulse is gated from the pulse decoding circuit 58 either to the timing circuit of the first 515 272 socket 54A or to the timing circuit of the second electrical socket 54B.

In order to achieve the above-mentioned synchronization, information must be stored in the system as to which phase in a 3-phase system resp. receiver is connected. This information, together with some other data regarding the structure of the system, is stored during installation of the system in the EEPROM memory 36 in the microprocessor part of the control unit (see Fig. 2). Alternatively, the electronics of all receiver units can be switched on at a certain specific phase.

In the system, as shown in Fig. 1, a load monitor 14 is connected between the control panels 16 and the control unit 10. In, for example, a parking space with electrical outlets, the power supply is usually divided into a number of groups, where each phase is generally secured with a fuse of 25-40 Ampere. Each such phase fuse (group) supplies a number of electrical outlets 54.

A load monitor 14, which is shown in block diagram form in Fig. 4, is supplied with information about resp. phase by means of a load sensor 70 in the form of a current transformer, which is connected to a resp. phase for each phase fuse as above, see Fig. 4A. The load monitor 14 itself comprises a measuring point selector (measuring selector) 72, which cyclically senses the various connected phases and supplies information about the load on these to an A / D converter 75 via an amplifier 73 and a detector 74. Measuring logic comprising A / The D-converter 75 for converting the measured values into digital signals and a micro-controller 76 connected to the A / D converter 76 for administration and control of the measuring sequence processes this information and transmits it to the control unit 10.

The load monitor 14 is normally connected directly via cable 17 to the control unit 10, if this is located in connection with the group exchanges, whereby measured values are transmitted serially to the control unit. The information can also be transmitted via the 230V network 13 by using a superimposed, high-frequency signal in the same way as in the information transmission from the control unit 10 to the receiver units 12. In this case, the load monitor 14 must be connected to the 230V network 13 via an HF generator. 90 and a power amplifier 92 for transmission and an FSK demodulator 94 and a pulse decoder 96 for reception. The load monitor, like the receiver units 12, has its own, preferably fixed ID code, with which it is ordered to send the next measured value.

The measured values are sent cyclically together with the current measuring point number as a pulse train.

Finally, the load monitor also includes a power supply unit 78 for 5- and 35-volt supply to the circuit.

The load monitor 14 continuously measures and checks all measured values cyclically against a programmed limit value. When sending measured values back to the control unit 10, priority is preferably given to those measured values that exceed the limit value.

Using the above measured values, the control unit 10, which must also have stored information regarding the group to which each socket is connected, can with a suitable program algorithm control the on / off status of consumers connected to the sockets in such a way that overloading of the phase fuse is avoided . The principle of this control is as follows: the various users connected to the sockets have a usage diagram, which is stored in the memory circuits of the control unit. These schedules can be determined in advance or can be changed by means of, for example, the above-mentioned button telephones.

The preferred algorithm is to first switch off such users who have a later service life programmed and secondly distribute the power cyclically, so that each electrical outlet may be switched on for a certain time and that the maximum number of switched on users is limited so that the fuse does not overloaded.

In an alternative preferred embodiment, order signals are sent from the control unit 10 to the receiver units 12, which order on or off of resp. power outlet.

This differs from the embodiment described above, where only the order for switching on is sent and the receiver units 12 switch off the electrical outlets in the absence of this order signal. This latter embodiment has the advantage that less information needs to be sent, which enables the connection of more electrical outlets without extending the cycle time of the system.

In a further embodiment, the receiving units 12 also comprise means for sensing the current load and means for transmitting information relating thereto to the load monitor, which, based on the sum of all loads on a phase, can determine whether overloading of this phase risked. This provides a more expensive, but more flexible system than those mentioned above. Although preferred embodiments of the invention have been described in the above examples, the system of the invention may be varied within the scope of the appended claims.

For example, the system can be used in industry and the home to monitor power consumption in a number of groups of electricity consumers, so that overloading of main fuses is avoided.

Claims (8)

515 272 10 Patent claims A system for controlling electrical power supplied to electrical outlets (54A, 54B) connected to an electrical network, the system comprising a central control unit (10), means (11, 16) for transmitting information between the control unit and the electrical outlets and a a plurality of receiver units (12) connected between the electrical network and the sockets, and a load monitor (14) arranged to sense the current in resp. phase of a group control panel (16) connected to the network and connected to the control unit (10) to regulate it to resp. electrical outlets (54A, 54B) applied electrical power depending on the current load on resp. group phase, so that overloading of the group centre's phase fuses is avoided, characterized by a phase sensor (60) arranged in the receiver unit (12) connected to the network (13), which phase sensor synchronizes with a gate signal by means of gate gates (62) phase position, so that a positive phase of the mains voltage results in control of a first electrical outlet (54A) and a negative phase of the mains voltage results in control of a second electrical outlet (54B). 2. A system according to claim 1, characterized in that information is transmitted from the control unit (10) to the receiver units by means of FSK-modulated signals superimposed on the mains voltage. 3. A system according to claim 2, characterized in that said modulated signals are modulated with a frequency of 125-140 kHz. 4. A system according to any one of claims 1-3, characterized in that information is transmitted cyclically from the control unit (10) with a cycle time of 15 s. 515 272 ll System according to one of Claims 1 to 4, characterized in that when sending measured values back to the control unit (10), priority is given to the measured values that exceed a predetermined limit value. System according to one of Claims 1 to 5, characterized in that it primarily switches off users who have a later service life programmed in and secondly distributes the power cyclically, so that each electrical outlet (54A, 54B) receives be switched on for a certain predetermined time and that the maximum number of switched on users is limited so that the fuse is not overloaded. System according to any one of claims 1-6, characterized in that means (70) arranged in connection with said group center (16) for sensing the load on phases connected to the group center, which means (70) are connected to the load monitor (14). . System according to one of Claims 1 to 6, characterized in that the means for sensing the current load and means for transmitting information relating thereto to a receiver arranged in the load monitor (14) arranged to, outgoing from the sum of all loads on a phase, determine whether overloading of this phase is at risk.