A TELEMETRY TERMINAL

Abstract: A telemetry terminal for controlling and metering consumption of electricity, water etc., at a consumer's premises comprises a programmable processor (43) which has means (42) to receive instructions over the phone line to operate switching controls (48) and to transmit readings stored in the processor (43) from meters (46, 47) to a central control station over the phone line, and may include a switching control routine in the event of an interruption to the phone line.

Description: A Telemetry Terminal Technical Field This invention relates to remote monitoring or control of loads and will be described in terms of the control or monitoring of the users of an electricity utility but it may also be used in respect of other utilities such as gas and water. Background Act In an electricity supply grid it is known to switch off-peak hot water systems by "tone" signals transmitted by the utility over the supply lines. This requires the injection of large currents into the power grid at fre- quencies of about 400 Hz. In a known electronic meter reading system meters electronically store readings at the consumer's premises and the meter reader connects a portable meter reading device to the electronic meter and the reading is transferred to the portable device. Summary of the invention The system described herein makes it possible for the utility to transmit control signals over the telephone lines to the user's equipment to perform the switching operation. Alternatively the switching may be controlled by an electronic clock at the subscribers premises and the switching times may be varied by signals transmitted over the telephone line. Other embodiments disclose techniques for remotely reading the mete at the user's premises. Our provisional application No. PH 3553 (P. Naish 1) discloses a method of off-peak switching over the telephone line which has a back-up "clock" at the user's premises in case of failure of the telephone line. A further embodiment makes possible load shedding on a se lective basis where an Indication from a sub-station to the utility's con¬ trol system shows that the load on the sub-station has reached a maximum peraiissable level. Another embodiment allows load shedding at an individual user's prem¬ ises where the user's load exceeds a maximum peraiissable. This system may allow short term loads in excess of the maximum. A maximum peraiissable load per consumer may be stored in a memory and load shed when this load is exceeded for a specified time. A further embodiment which may be applicable e.g. where the tariff changes when use over a period exceeds a preset total e.g. excess water rate would enable the system to compare cumulative use with the average permitted use and to give an indication to the user when actual use ex¬ ceeded the permissible average. During periods of water restrictions out¬ side taps, routed through a remotely controllable valve, can be shut off for specified periods. Accordingly intelligent units, referred to as utility management ter¬ minals (UMT) are installed at the user's premises and these are capable of reading meters and switching loads. Brief Description of the Drawings Pig. 1 shows a block diagram of a system embodying the invention; Pig. 2 is a block diagram of a UMT; Fig. 3 shows a more detailed embodiment of the UMT of Fig. 2. Best Mode of Carrying out the Invention Pig. 1 shows the main elements of the system. In the first area 1 is the equipment at the utility's central control, while area 2 shows the equipment installed at the telephone exchange and area 3 shows the equip¬ ment at the consumer's premises. At each consumer's premises there may be installed meter reading equipment 4 or load control equipment 5 or both. There may be more than one of each device for each consumer. The subscriber is allocated a utility management terminal (UMT) 6 which is connected to the telephone line 7 in parallel with the telephone. At the telephone exchange the line 7 is connected to a scanner 8 which is capable of monitoring about 2000 such lines. This connexion is made on θthe subscriber line and no exchange switching equipment need be involved. The scanners act to concentrate the information and pass it to the host computer 9. The UMTs are linked through the host computer to the Central Control 10. This Computer 9 acts as a special purpose message switch which routes messages to the UMT's and checks acknowledgement. Should a IMP fall to acknowledge a message or should there be a failure affecting the system, a report is sent to the Central Control 10. Some of the features which may be provided by the system are set out below. The status of the UMT is available at the Central Control Equipment by an interrogation/response sequence and there may be an on-site status indi¬ cator. Should power be removed from the UMT for up to 60 seconds then, when power is restored the UMT will return the load to the state it was in before the interruption. A capacitor or battery may be used to sustain the status. Should power be removed from the UMT for more than 60 seconds then, when power is restored the UMT may be prograπmed to ensure that the load is switched off. Restoration to the previous state will be initiated by a command from the Central Control Equipment. Should a UMT be installed in an area where Telecom circuits are not yet available then it will be possible to set the time of day in that UMT. The UMT will then operate as a time clock and will turn the load on and off at pre-programmed times. Should a UMT lose communications with the the Scanner to which it is con¬ nected that UMT may be prograπmed so it will operate as a time clock. A UMT is individually addressable and is able to be switched on or off at an time frcm the Central Control Equipment. A UMT can be allocated to any op erating group frcm the Central Control site. On-site access will not be necessary to change any UMT's group. The group to which a UMT has been al located is known at the Central Control site. Loss of communications with a UMT is reported to the Central Control site. The Central Control Equipment 1 has sane or all of the following capa bilities. Control of the customer loads connected to the network. Load manage¬ ment to control UMT groups in a specified order of priority. System load data from the SCADA system is used as the control input. The objective here is for the integral of load over a fifteen minute period to approxi¬ mate a straight line frcm 0 to the maximum load for that period. The Con¬ trol Equipment can turn on or off an individual UMT load with a single conmand. The Control Equipment has the ability to turn on or off all UMT loads in a particular group with a single command and turn on or off all UMT loads with a different conmand. The Control Equipment may execute an entered prograπme to periodically turn groups on or off. There may be dif¬ ferent prograπmes for holidays and weekdays. It is possible to manually override the programme. Password protection may be used to prevent access to sensitive parts of the Central Control Equipment software. It provides the ability to read accumulated meter pulses frcm the UMT. All system er¬ ror messages may be logged on a printer with a time and date stamp. These messages will include reports of any UMT failures as well as any ccmmuxi- cations problems. Should there be a loss of comπunications to the UMT or should a tele¬ phone circuit be unavailable for a particular consumer when a UMT is in- stalled then the UMT will revert to an automatic fallback state. This is referred to as the Preset Automatic Operating Facility (PAOF) feature and will allow load control to be maintained through any temporary interruption to the network. PAOF functions will come into operation if conmunications are dis¬ rupted for more than a predetermined period such as 1 hour. The functions that are available are described below: The UMT will switch the connected load ON and OFF at preset times. These times may be set in all of the following ways: - In the factory before delivery. By the Authority before installation. By the Authority at the time of installation or By the Authority after installation. The UMI may be supplied with one preset ON time and one preset OFF time. These times can be programmed to meet the Authority's requirements and are contained in the UMT EPRCM. The Authority will be able to produce UMT EPROMs with alternative switching times, using a master EPROM and may set up the required switching times using an EPRCM programmer. These EPROMs may be Inserted in UMTs prior to installation or, should it be necessary they may be installed on site at any time. The program may be altered by a message transmitted over the telephone line. In addition, It is possible to change the default time at which the UMT switches, by making on site adjustments without changes to the EPROM. The time of day is progranmed into an internal clock in each UMT when it is installed. This is done by means of switches that are accessible when the cover of the UMT is removed, or by instruction over the phone line. The clock may be set, in increments of 30 minutes, to any time between 8 a.m. and 4 p.m. This time is maintained by a high precision crystal. The Optional PAOF Functions provide significant enhancements to the PAOF mode of UMT operation. The switching times may be progranmed into a UMT from the Central Control site provided that both power and communi¬ cations to an operating UMT are available. The UMT can store previous ON and OFF switching times. This enables a UMT to continue operating as it did previously. The UMT can maintain a time reference during extended power failure so that operation will recoπmence with the correct time of day after an extended loss of mains power. This capability can extend to cover loss of power for several days. The system may be configured to operate in either a digital or analog network. In Fig. 2 and Fig. 3 embodiments of an UMT are shown in block form. When a message is received by the EMT, it is fed into the processor 43 which recognizes the message as a request for meter reading, instruction to switch loads, routine tests etc. and is prograπmed to respond appropri¬ ately. The line interface 41 may serve the purpose of coupling signals to the phone line while isolating the UMT power supply frcm the line. It may com- prise e.g. an opto-coupler or a line transformer. The receiving circuit 42 detects the presence of a Utility Management System UMS message on the phone line and passes the message to the micro¬ processor 43. The receiver 42 is able to recognise a UMS code and prepare the signal for the processor. If the signal is digital the receiver may perform pulse shaping functions while if the signal is analog the receiver may convert it to a suitable digital format. In a present embodiment the signal Is an FSK signal which the receiver converts to a digital signal. The message is stored in a conmand buffer in processor 43, checked for validity and actioned. The message may be one which causes the microprocessor 43 to operate a relay such as 48 or 49 or latch 48a of Fig. 3 or to transmit a meter read¬ ing from meters 46 or 47 stored in the processor memory or in NOVRAM 122 of Fig. 3 via the transmit circuit 45 over the phone line to the scanner 8 at the telephone exchange 2 (See Fig. 1 ) where the information is processed by host computer 9 and relayed to the utility's central control 1. The transmitter 45 may be digital or analog depending on the network. In one embodiment involving an analog network the microprocessor 43 may generate digital signal which the transmitter converts to a suitable analog format, e.g. FSK. In a further embodiment the processor 43 may generate the analog signal which the transmitter 45 amplifies for transmission. Transmitter 45 and receiver 42 may be incorporated into a single IC modem. Supervisory tone may be applied to line via tone generator ciruitry 100a, 100b. For a digital network the processor generates a digital signal and the transmitter then becomes a digital line interface and may perform such functions as equalization. A system of acknowledgement messages (handshakes) may be used to con¬ firm receipt of messages at either end. This may be particularly important where the telephone is being used by the subscriber at the time a series of messages is being interchanged. The system may operate by transmitting bursts during conversation and this leaves the messages open to corruption by the speech signals. In this arrangement, therefore, it is necessary to transmit signals which confirm the successful receipt of a message. In the absence of such an acknowledgement the sender repeats the message. When the Central Control Equipment does not receive an acknowledgement, It will repeat the messge a predetermined number of times or until acknowledged earlier, and report a fault if unsuccessful. Also shown connected to the microprocessor is a clock 44 and a bank of switches 51. The switches can be used to set the time of day to operate the local clock. Tamper protection in the form, e.g. of one or more switches which are operated for instance when the cover is opened, are provided at 50. A large capacitor 52 may also be included to preserve the contents of the processors memory should there by a loss of power to the UMT. Using this capacitor the UMT can store the meter reading or pulse signal frαn the meter so the data is not lost. In another embodiment meter readings are stored in non-volatile RAM to provide a permanent record of the reading at the time of failure. The UMT includes a clock oscillator 44 which maintains a time of day clock in the microprocessor logic so that, in the event of an interruption to the telephone line, functions such as off-peak switching can be main¬ tained. The system offers the Authority the ability to control peak load con¬ ditions with more precision than was previously possible and the greater predictability of the peak is of great value to electricity generating au¬ thorities. Where the utility has Installed a Supervisory Control Automatic Data Acquisition system (SCADA), it has information showing the load trend. It is thus possible to predict reasonably accurately when the load will ap¬ proach a permitted maximum. Using this information it is possible to begin a load shedding program to avoid exceeding the permitted level. With a program incorporating a suitable hysteresis factor the load can be main¬ tained below this level. Fig. 3 is a more detailed functional diagram of an embodiment. The phone line connects to interface 41 and is bridged by protection circuitry 200. Incoming messages frcm the phone line are detected by 42a which would be an FSK input filter in the case of an FSK signalling system. Filter 42a feeds into demodulator 42b which transmits the demodulated signals to P16. The incoming message may be: a) a switching conmand b) a meter interrogation c) a reprogranming conmand d) a routine test In Fig. 3 address latch 120 and memories 121 and 122 are used to con¬ serve space in the microprocessor 43. In the case of a switching conmand the microprocessor 43 routes the ccπmand over data bus 110 to output latch 123 which initiates the switching operation and then causes an acknowledgement signal to be transmitted via terminal 10 to line. In the case of an FSK system this signal would be sent via FSK Buffer/Filter 45a, controlled by output energy level switch 45c, to FSK output switch 45b and to line through interface 41. In the case of a meter interrogation, either an absolute readout meter or a pulse generating meter may be used. Where the pulse meter is used a cumulative count is stored in the microprocessor or an associated memory. In the case of an absolute meter readout, the reading may be taken directly fr n the meter. The meter interrogation conmand causes the meter reading or the cumu¬ lative count to be fed to the line again via P10. Read/Write decode circuitry 140 can be used to modify the micro¬ processor data by altering NOVRAM 122. This may be used, for example, to update the load switching time, or alter other program features. Routine tests may be used to test the operation of the subscriber ter¬ minal unit. Such tests may comprise a memory test, check of transmit and receive circ'uitry or functional tests such as a brief operation of the load relays and receipt of an acknowledgement signal. Other functions may simi¬ larly be monitored. Other commands which may be implemented include: Enable load survey; this causes the UMT to transmit data on one or more meters to the central control equipment at fixed intervals of e.g. 15 minutes to allow load sur¬ veys to be made. A survey cancel command causes the survey to be discon- - tinued. Maximum Demand Interrogation; the UMT stores the maximum energy con¬ sumed during a fixed period (15 minutes) in a register and the time of day when this occurred, and this is transmitted by the UMT on interrogation. A further coτmand resets the register. Set load groups; defines which group commands will affect the UMT loads. The UMT also allows the meter readings to be charged at different rates during the day. This is achieved by having a number of registers each to store pulses generated during specific hours during the day. In this way peak usage period pulses are stored in one register and low usage period pulses are stored in a further register and there may be one or more intermediate registers. The time of day clock in the UMT is used to switch the meter pulses into the various registers depending on the time the pulses are generated. When the meters are read the meter register readings are read out over transmitter 45 in turn and the appropriate tarrif rates applied to the various readings at the central control equipment when ac¬ counts are prepared. Additional registers may be provided to allow differentiation between week day and weekend or holiday consumption. Where there are a plurality of meters attached they may be read in se¬ quence so their readings are applied to the appropriate registers by micro¬ processor 43. The meter outputs may be sampled at a higher rate than the maximum rate at which pulses are generated in the meter to allow for redun¬ dancy verification, e.g. a pulse not being recognized unless it is present on two successive samples. The UMT can be reprog aπmed frcm the Central Control Equipment by transmitting a reprogra ming message over the telephone line. The message is decoded stored in the microprocessor command buffer, verified and then applied to e.g. NOVRAM 122 over line 111 to rewrite the portions of the program it is desired to alter. For instance it may be desired to amend the time-of-day tarrif scales when daylight waving is introduced or re¬ moved, or otherwise make allowance for seasonal peaks. Industrial Applicability The Invention discloses equipment for remotely reading meters and con¬ trolling loads connected to utility supplies such as electricity, water and gas. The information and instructions are transferred between the sub¬ scriber's premises and a central control via the telephone network.

Claims: [received by the International Bureau on 26 May 1987 (26.05.87): original claims 1-16 replaced by amended claims 1-17 (3 pages)] 1. A utility management terminal comprising transmitter means con¬ nected to the consumer's telephone line to transmit information to the telephone line, the terminal comprising one or more metering means each adapted to produce a meter signal indicative of the consumption measured by its respective meter, storage means to store the meter signals, transponder means responsive to a first command signal received over the telephone line to cause one or more of the meter signals stored in the storage means to be transmitted to the telephone line, one or more utility control devices con¬ trolled by utility control logic means to execute a load shedding routine to switch the or at least one of the utility control devices either in re¬ sponse to a second command signal or under the control of a time of day program. 2. A utility management terminal comprising transmitter means con- neeted to the consumer's telephone line to transmit information to the telephone line, the terminal comprising one or more metering means each adapted to produce a meter signal indicative of the reading of its respec¬ tive meter, transponder means responsive to a first command signal received over the telephone line to cause one or more of the meter signals to be transmitted to the telephone line, one or more utility control devices con¬ trolled by utility control logic means to execute a load shedding routine to switch the or at least one of the utility control devices either in re¬ sponse to a second conmand signal or under the control of a time of day program. 3. A utility management terminal as claimed in claim 1 or 2, wherein the transponder means includes acknowledgement signal means to transmit an acknowledgement signal to the telephone line when a signal is received over the telephone line. 4. A utility management terminal as claimed in any one of claims 1 to 3, wherein the terminal is connected to the telephone line in parallel with the consumer's telephone. 5. A utility management terminal as claimed in any one of claims 1 to 4 wherein the transponder means includes receiver means connected to a con¬ sumer's telephone line to receive control signals transmitted over- the telephone line, ' the utility control logic means responsive to the receiver means output to control utility devices of one or more utility supplies or part thereof at the consumer's premises. β. A utility management terminal as claimed in claim 4, wherein the utility control logic means includes electronic clock means and an auton¬ omous power supply or store capable of maintaining clock and logic opera¬ tion in the event of a failure of the telephone line, the logic means including processing means to execute a predetermined control program to control the utility control devices in the event of a failure of the tele¬ phone line. 7. A utility management terminal as claimed in any one of claims 5 or 6 wherein the utility control logic means includes a microprocessor and wherein the storage means are part of, or controlled by the processor, the microprocessor being progranmed to execute instructions received via the receiver means. 8. A utility management terminal as claimed in claim J, wherein the microprocessor programming is stored in the microprocessor and for in aux¬ iliary storage means, and wherein means are provided to alter the program¬ ming in response to signals received via the receiver means. 9. A utility management terminal as claimed in any one of claims 1 to 8, wherein the storage means comprises, for the metering means, two or more storage registers and wherein logic means are provided to direct the meter signals to which ever of the storage registers is selected by a register selection signal produced by a register selection signal generator. 10. A utility management terminal as claimed in claim 9, wherein the register selection signal generator comprises a programmable time-of-day clock which generates the register selection signals in accordance with a selected program. 11. A utility management terminal as herein described with reference to the accompanying drawings. 12. A utility management terminal as claimed in any one of claims 1 to 11 including means responsive to a telephone line fault and wherein the utility control logic means is responsive to the detector means responsive to the line fault to Initiate the load shedding routine under the control of the time of day program. 13. A utility management system comprising central processing means ar¬ ranged to transmit control signals to and receive information from a plu¬ rality of utility management terminals as claimed in any one of claims 1 to 12. 14. A system as claimed in claim 13 including concentrator means inter¬ posed between the central processing means and the utility management ter¬ minals. 15. A system as claimed in claim 13 or claim 14 including utility de¬ mand metering equipment transmitting information on the demand on the util¬ ity to the central processing means and wherein the central processing means is prograπmed to transmit load shedding commands to one or more util¬ ity management terminals when the demand exceeds a first threshold, and to transmit a load restoring command to one or more of the utility management terminals which has been shed when the demand is below a second threshold. 16. A system as claimed in claim 15 wherein loads are shed on a cyclic basis between groups of consumers. 17. A utility management system as herein described with reference to the accompanying drawings.

Inventors: BELLIS GRAEME JOHN, HANSFORD ALAN EDWARD, NAISH PETER JACK, STANBURY EVAN JOHN, WATKINS GREGORY DOUGLAS, BELLIS, GRAEME, JOHN, HANSFORD, ALAN, EDWARD, NAISH, PETER, JACK, STANBURY, EVAN, JOHN, WATKINS, GREGORY, DOUGLAS
Applicants: STANDARD TELEPHONES CABLES LTD, STANDARD TELEPHONES AND CABLES PTY. LIMITED
Application year: 1986
Main classification: H04Q9
IPC codes: H04M11