System for utility demand monitoring and control using a distribution network
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is related to the following patents and pending applications of the present assignee: 
     U.S. Pat. No. 5,084,903, issued Jan. 28, 1992 for MODULATION AND DEMODULATION SYSTEM EMPLOYING AM-PSK AND QPSK COMMUNICATION SYSTEM USING DIGITAL SIGNALS; 
     U.S. Pat. No. 5,088,111, issued Feb. 11, 1992 for MODULATION AND DEMODULATION SYSTEM EMPLOYING AM-PSK AND FSK FOR COMMUNICATION SYSTEM USING DIGITAL SIGNALS; 
     U.S. patent application Ser. No. 07/345,490 filed Apr. 28, 1989 for DISTRIBUTED INTELLIGENCE NETWORK USING TIME AND FREQUENCY MILTIPLEXING, now abandoned; and 
     U.S. patent application Ser. No. 07/778,031, filed Oct. 17, 1991 for SPECTRALLY EFFICIENT BROADBAND TRANSMISSION SYSTEM, now U.S. Pat. No. 5,272,700. 
     BACKGROUND OF THE INVENTION 
     This invention relates to a system for monitoring and controlling customer power demand in a utility such as electric, gas, and water, and more particularly the invention relates to an information distribution network for use in such a system which allows the connection and disconnection of customers in the utility, the collection and transmission of user demand requirements, and the control of user demand for utility services. 
     Domestic residential demand for electric power is growing at approximately 2% annually. Although utility companies can maintain pace with this growth by constructing more peaking and power plants, this is not necessarily in the best interest of the utility companies and society at large. The factors of cost, fuel availability, and environmental concerns of both the utility company and the public in general have prompted a shift of emphasis from building additional generation capacity for satisfying the increasing demand to developing and employing a method and means of efficiency improvements, production facility optimization, and electrical conservation through demand side management. Implicit in this is the fact that not all electric power costs the same to generate. Power generated during peak times is more expensive than &#34;base-line&#34; power. For demand side management, utility companies will charge on a cost basis rather than an average use basis that has existed in the past. 
     Heretofore, systems have been proposed for communicating utility usage at a customer&#39;s home to a central office. For example, U.S. Pat. No. 4,086,434 discloses a remote condition reporting system including a microprocessor with memory and a firmware program, telephone dialing equipment, a clock, and a plurality of inputs from meter readings and the outputs of sensors. The system initiates telephone calls to the utility company central offices at predetermined intervals to report utility usage including time of day power usage metering. 
     Telephone line interface between users and a central control station has a number of limitations including slow transmission and low user saturation levels. Moreover, the centrally switched telephone system is not capable of providing simultaneous two-way communication with an entire service area population. Wireless radio systems have limited bandwidth and thus limited applications and flexibility. 
     The present invention is directed to a monitoring and control system in which communication occurs through a fully distributed digital telecommunications switch without a centralized routing and handling facility. The distribution network is deployable to large numbers of residential and commercial customers for bi-directional real-time communication. While initially designed for use with an electric power utility, the invention is applicable in monitoring and controlling demand for other utilities such as gas or water, as well as for data services. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the invention, a controlled load management and feedback system includes a power company central computer facility, a plurality of home monitoring and control networks, and one or more wide band distribution networks interconnecting home monitoring and control networks and the central computer facility. The distribution networks connect to one or more central computer systems through substation gateways via high-speed digital lines. 
     The home monitoring and control network is located and operated within the power utility customer&#39;s home and includes electrical control, monitoring, and measurement devices which allow the utility to monitor electrical consumption in real time, assist the customer in optimizing electrical power consumption, and communicate real-time consumption and changes in consumption to the power utility via the distribution network. Further, the home network permits automatic meter reading and remote service disconnect and reconnect. 
     The distribution network includes a wire-based (hybrid fiber/coaxial cable) distribution system and an intelligent utility unit (IUU) which interfaces with the home network. The IUU controls, communicates, and configures devices within the home network, and communicates information from the home network back to the utility central computer via the distribution system. The distribution network is configured in cells or small hubs which support 250-2,000 users at a time. 
     The utility central computer includes a T-based communication digital backbone network which communicates with a distribution network through gateways typically located within a power substation. The backbone network consolidates traffic from different substations and routes the traffic to the utility host computer, thus providing access to every user on the system. The host computer is able to forecast trends and predict when demand will exceed supply, thus allowing corrective action to be taken. The computer can also generate reports for utility management and consumers showing usage and savings through demand management. 
     The invention and objects and features thereof will be more fully understood from the following detailed description and the appended claims when taken with the drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration of an electric power demand monitoring and control system in accordance with one embodiment of the present invention. 
     FIG. 2 is a schematic illustration of the home monitoring and control network in the system of FIG. 1. 
     FIG. 3 functionally illustrates the intelligent utility unit (IUU) in the home network of FIG. 2. 
     FIG. 4 functionally illustrates bandwidth allocations for the home network in the distribution system. 
     FIG. 5 illustrates the bi-directional distribution network. 
     FIG. 6 is a functional block diagram of the digital backbone network which interconnects the utility company host computer and the distribution networks. 
    
    
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENT 
     Referring now the drawing, FIG. 1 is a functional diagram illustrating a power monitoring and control system in accordance with one embodiment of the invention. Communication in the system is between a mainframe host computer 10 at the power utility company central offices and the homes 12 of customers serviced by the utility. The home network for each customer includes electrical control, monitoring, and measurement devices. An intelligent utility unit (IUU) 22 located at each customer&#39;s home allows the host computer 10 to monitor electrical consumption in real time and help the customer optimize electrical power consumption. The IUU communicates with the host computer 10 through a bi-directional data distribution network 14 which is connected at a substation 16 through a bridge 18 to the digital backbone network of the utility company, which is in turn connected to a Bridged Gateway interface 20 of the host computer 10. The distribution network 14 comprises a coaxial or optical fiber cable in which there is a plurality of time and/or frequency division multiplexed channels. The digital backbone network may be a combination of copper and high volume fiber optic cables. The digital backbone network runs over high-speed digital lines. 
     FIG. 2 is an illustrative embodiment of the home network located at each customer&#39;s home. The IUU 22 is the interface between the home network and the distribution network 14. The home network includes electrical control, monitoring, and measurement devices located and operated within the customer&#39;s home. An electronic power meter 24 allows the reading of total power consumed to date, total power being consumed at present, and the change in power consumed from the last period monitored. Power disconnect and reconnect of the electronic power meter is controlled at the power utility company central office through the host computer 10. The IUU is further connected to sensors and switches connected to the home heating, air conditioning, lighting, water heater, thermostat, and other internal circuits, as illustrated. Further, an optional user interface is provided with a readout provided by the television set or LCD panel, for example. FIG. 3 is a functional diagram of the IUU in interfacing with the home network and the distribution network 14. 
     The distribution network allows a wide variety of digital information processing devices plus simultaneous switched voice (telephone), data, and full motion NTSC video services to communicate simultaneously over a single wiring system as illustrated by the bandwidth allocation of FIG. 4. The distribution network comprises a single high-speed digital bus with the channel bandwidth allocated into time slots, signalling bandwidth, and overhead functions. A plurality of 5.018 MBPS data streams are provided with each data stream organized to include 28 full duplex time slots utilizing 3.584 MBPS bandwidth and which can be allocated for voice or data traffic. An out-of-band signalling channel operating at approximately 640 KBPS is shared by all units on the network for configuration and call processing information exchange. Further, bandwidth set aside for overhead functions such as relative system timing, time slot preambles, and time slot and signal bandwidth synchronization is included in each 5.018 MBPS stream. For data applications, a fixed number of time slots, typically between 1 and 8 and up to a maximum of 24 are permanently allocated and configured for data services on the distribution portion of the network. These time slots are shared between all IUUs on the network. In essence, a portion of the network bandwidth is allocated for data LAN services. When a time slot is allocated for data services, either or both the forward and reverse time slots, i.e., both ends of the full duplex time slot, can be allocated and used for data transmission. Under this convention allocation of additional time slots for data services increases the LAN speed by 64 KBPS per time slot. 
     Since the distribution network is structured like a bus oriented LAN, random access or control contention is required to manage access to the IUUs. Either a carrier sense multiple access (CSMA) or a carrier sense multiple access with collision detection (CSMA/CD) access mechanism is employed. In CSMA, a node listens for network traffic and if nothing is heard, packets are sent to the host computer. Problems can occur when multiple nodes send before activity can be detected. In CSMA/CD, senders listen while transmitting, and back off and retransmit when collisions are detected. Throughput is high, ranging between 80% and 90%. The selection between CSMA and CSMA/CD is based on the tradeoff between enhancement and performance achieved by using a CSMA/CD mechanisms versus the issues of cost and implementation as compared with CSMA. The important consideration for a network access method is that it should be stable under heavy loads, i.e., it should back off for longer periods of time during peak operation. The longer backup times should not affect network operation since time access of most applications are near real time even under heavy load conditions. 
     FIG. 5 illustrates the bi-directional full duplex organization of the distribution network. The radio frequency spectrum is typically divided into outbound or downstream from the host computer head end of the cable towards the end user devices and inbound or upstream from the end user devices towards the head end. The RF spectrum on the cable can be organized in one of three ways: sub-split, mid-split, or high-split. These terms refer to the particular segments of the RF spectrum used. 
     In a sub-split system, the frequencies from 5 to 30 MHz (4 channels) are used to carry signals in the inbound directions and the frequencies from 50 MHz to 1 GHz (80+channels) are used to carry signals in the outbound direction. This is illustrated in Table 1. 
     In a mid-split system, the frequencies from 5 to 108 MHz (17 channels) are used to carry signal in the inbound direction, and the frequencies from 162 MHz to 1 GHz (50+channels) are used to carry signals in the outbound direction. See Table 2 for a representative mid-split cable spectrum. 
     In a high-split system, the frequencies from 5 to 175 MHz (30 channels) are used to carry signals in the inbound direction, and the frequencies from 220 MHz to 1 GHz (35+channels) are used to carry signals in the outbound direction. See Table 3 for a representative high-split cable spectrum. 
     A multi-tiered addressing scheme is employed in the network. Each IUU contains the following address structure: 
     Physical unit address-six-byte address unique to every unit. The address is written in HEX and coded into each IUU. 
     Group address-allows addressing of assigned group less than all users. 
     Broadcast address allows addressing of all system users. 
     This addressing structure allows the network manager to directly communicate with each individual IUU, a group of IUUs, and all IUUs. 
     The gateway between the distribution network and the digital backbone interfaced to the host computer is located in the utility company substations. A Power View bridge (PVB) provides the routing function between the distribution network and the backbone network. The bridge processor keeps track of IUU addresses and the network processor address and performs the routing function for all packets between the networks. The bridge also performs a filtering function in passing data only to valid known addresses. 
     FIG. 6 is a functional block diagram of the digital backbone network which interfaces the host computer with the plurality of distribution networks. The backbone network includes a Frame Relay T1 interface for providing the interface between the gateway and the backbone network. A PowerView Network Processor (PNP) which provides an interface between T1 data streams and the utility host computer which provides the management of the overall network. The backbone network can be organized as a star, ring or bus. The actual topology is not important since circuits will be dedicated from the utility substations to the host computer. The digital circuits terminate at a PNP near the utility company&#39;s host computer. The backbone network can operate from T-1 rates upwards and exceeding T-3 rates, depending upon network and utility size. The T1 network distribution media is twisted wire, optical fiber, coaxial cable, or microwave. The T3 networks are either fiber or microwave. Minimum network speed is T-1. Network addressing is a function of the circuits dedicated to the distribution network and a lower level addressing between the IUUs and the utility company&#39;s host computer. Alternatively, an ATM interface could provide the interface between the gateway and the backbone network. An ATM interface router would then interface between the backbone network and the host computer. 
     The application package within the host computer includes the ability to collect information about time of day power consumption, the ability to remotely configure the home network through the IUU, the ability to change the price tier in real time either up or down as a function of power generation and consumption, and the ability to collect and process the customer&#39;s utility bill which breaks down power consumption by device, time of day, override conditions, and the like in order to provide an itemized billing statement to the customer. 
     There has been described a system for utility demand monitoring and control and including a distribution network which facilitates demand side management of utility consumption. While the system has been described with reference to an illustrative electric power utility embodiment, the description is illustrative of the invention and is not to be construed as limiting the invention. The system can be used with other utilities such as gas and water as well as with telephone and cable television networks. Other functions are readily incorporated such as security systems. Thus, various modifications and applications will occur to those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims. 
     
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SUB-SPLIT BROADBAND                                                       
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MID-SPLIT BROADBAND                                                       
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HIGH-SPLIT BROADBAND                                                      
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