Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H1/00—Details of emergency protective circuit arrangements
  • H02H1/0061—Details of emergency protective circuit arrangements concerning transmission of signals
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/006—Calibration or setting of parameters
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
  • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations

Definitions

• the present invention generally relates to digital protective relays and protective control of electrical power distribution systems. More particularly, the present invention relates to digital protective relays having communications capabilities.
• Intelligent protective relays which incorporate a digital microprocessor for providing protective control of power distribution systems.
• digital protective relays that have communications capabilities.
• the communications capabilities are typically relatively limited, and might include, for example, an application layer protocol such as Modbus RTU or ASCII for communication over a Universal Asynchronous Receiver Transmitter (UART) data link layer with an RS485, RS232 or other fiber optic physical layer interface.
• UART Universal Asynchronous Receiver Transmitter
• Typical digital protective relays having a communications capability support only one application layer communications protocol, even where the relay includes multiple communications ports.
• U.S. Patent 5,680,324 discloses a communications processor for electric power substations.
• the communications processor includes an electronic network system with seventeen individual communications ports, four quadrature UART devices, each of which serves four of the ports, and a microprocessor which processes and control the flow of data under the control of stored control programs, command settings, and command logic. Relays, meters, or other intelligent electronic devices are connected to some of the ports, and remote terminal units, local computers, or a modem are connected to master ports.
• the communication processor has a capability of communicating with the various port devices through an ASCII communication format.
• the processor is capable of supporting simultaneous communication with multiple devices and users.
• the processor is a centralized communication device, which is separate and distinct from the protective relays, meters, and other port devices. Accordingly, the '324 patent does not focus on the communications capabilities of the relays or other port devices.
• a digital protective relay To further enhance the utility of a digital protective relay, and to provide more comprehensive protective control of power distribution systems, it would be desirable to improve the communications capabilities of digital protective relays. More particularly, it would be desirable for a protective relay to support multiple communications protocols and multiple communications network profiles. It would also be desirable for a protective relay to communicate concurrently over different types of communications networks, such as well-known local area networks (LANs), wide area networks (WANs), and the internet and to communicate sequentially in different protocols over the same communications port. It would further be desirable for a relay to allow user selection of the protocols and/or communications profiles. Known protective relays do not sufficiently address these needs.
• the present invention overcomes the problems described above, and achieves additional advantages, by providing for a protective relay which includes connections for operatively coupling the relay to an electrical distribution system, at least one communications port for communicating relay information over a communications network, and processing circuitry for monitoring the electrical distribution system via the connections, where the processing circuitry provides protective control for the electrical distribution system, generates relay information to be communicated over the communications network, and formats the relay information in one of a plurality of communication protocols.
• the communication network can be a LAN, WAN, the Internet, or other suitable network.
• the communications protocols can be selected by the user, and the relay can communicate using different communications protocols- simultaneously over separate communication ports, and serially over a single communications port.
• FIG. 1 is a diagram showing the communications protocols supported in some known industrial communications systems
• FIG. 2 is a diagram showing the communications protocols supported by some known Profibus-based communications systems
• FIG. 3 is a diagram showing the communications protocols supported by some known Ethernet-based communications systems
• FIG. 4 is a diagram showing the present invention's support of seven layers of communications protocols
• FIG. 5 is a block diagram of a relay according to one embodiment of the present invention which supports the communications profile of FIG. 4;
• FIG. 6 is a diagram showing an exemplary breakdown of communication classes and subclasses
• FIG. 7 is a diagram showing an exemplary protocol layering in a relay
• FIG. 8 is a diagram showing a top-level data flow in and out of the communication subsystem of the relay of FIG. 5;
• FIG. 9 is a detailed diagram of the internal processing components of the relay of FIG. 5. DETAILED DESCRIPTION Of THE INVENTION
• FIG. 1 a protocol stack or communications profile of known industrial communications systems is shown.
• Such known systems support an application layer protocol, such as Modbus or DNP 3.0, a data link protocol, such as UART (which uses 8 bits, 1 stop bit, and no parity bits), and a physical layer protocol, such as RS232, RS485, or fiber optic communications.
• an application layer protocol such as Modbus or DNP 3.0
• a data link protocol such as UART (which uses 8 bits, 1 stop bit, and no parity bits)
• a physical layer protocol such as RS232, RS485, or fiber optic communications.
• the remaining layers of the ISO 7-layer OSI model for generic communications systems presentation layer, session layer, transport layer, network layer
• FIG. 2 is a diagram showing the communications profile of a Profibus based communications system.
• This known system supports an application layer protocol in the form of FMS or DP, a data link layer protocol FDL, which is achieved by a chip set available from Siemens Corporation, and a physical layer protocol RS485.
• the Profibus system also supports the LLI protocol (for presentation and session layers) and the FMA protocol (for transport and network layers).
• the protocol stack of conventional Ethernet (i.e., according to the IEEE 802J standard) communications systems is shown in FIG. 3.
• the protocol stack includes an application layer protocol such as Modbus or DNP 3.0, a data link layer protocol according to the IEEE 802J standard so known as CSMA/CD), and a physical layer protocol according to the IEEE 802J standard (also known as 10BaseT/5/2/FL).
• the transport and network layers are supported by the TCP/IP or UDP protocols, and the presentation and session layers are not implemented or required in an Ethernet based system.
• the protocol stack includes an application layer format MMS, a presentation layer format RFC1006-Presentation, a session layer format RFC1006-Session, a transport layer format TP4, a network layer format CLNP, a data link layer format IEEE 802J, and a physical layer format IEEE 802J.
• the relay 10 includes connections 12 for operatively coupling the relay to an electrical distribution system 14.
• the relay 10 further includes one or more communications ports 16 for communicating relay information (e.g., monitored current and voltage parameters, or other power system data) over a communications network 18.
• relay information e.g., monitored current and voltage parameters, or other power system data
• the communications network 18 is preferably a peer-to-peer communications network, it will be appreciated that other suitable communications networks can be used.
• the relay 10 further includes a microprocessor 20 which is suitably programmed for monitoring various parameters derived from the electrical distribution system via the connections 12, for providing protective control of the electrical distribution system 14 (e.g., to operate a circuit breaker or perform some other protective action), and for generating and formatting relay information to be communicated over the communications network 18.
• the microprocessor formats the relay information in any one of the plurality of communication protocols identified in FIG. 4.
• the microprocessor is further suitably programmed to provide concurrent communications on the same or different communication channels; that is, the microprocessor 20 can: 1) format data for transmission over a single communication port in multiple data formats, which are selectable by the user; 2) receive data over a single communications port in multiple data formats by identifying and distinguishing between the format types of the received data; and transmit or receive data over multiple communications ports simultaneously in the same or multiple data formats.
• An additional advantage of the present invention is achieved by the microprocessor 20's support of the TCP/IP protocol.
• the support of the TCP/IP protocol in each relay allows any relay associated with the power distribution system to be accessed from any device capable of internet communication.
• power system data can be collected remotely from any or all of the protective relays associated with the power distribution system.
• the settings and operation of each relay can be adjusted remotely from any internet communication device. That is, the communication network 18 in FIG. 5 includes the internet.
• a security firewall e.g., password-protected authentication scheme, many of which are well-known
• the ports 16 of the relay of FIG. 5 are configurable, via processor 20, to support different communications protocols, stacks, and physical layer interfaces, such as Ethernet or RS485, independently and concurrently.
• the processor 20 manages the communications ports 16, and can also "virtualize" the various transport mechanisms on Ethernet (e.g., UDP datagram socket, TCP socket) so that they can be treated as physical ports, allowing asynchronous serial protocols to operate over
• relay communications can be implemented using subclasses of two base classes — COM_Port and COM Application. Together, one instance of each of these classes is selected via processor 20 to implement a protocol.
• COM_Port subclasses define physical layer requirements for specific serial hardware, or "virtual" serial ports (such as TCP or UDP host ports).
• the interface to the COM Port class generally corresponds to the standard known as RFC 1006, and is described in a document entitled "ISO Transport Service on Top of the TCP", the entirety of which is incorporated by reference.
• This document defines a standard connection-oriented interface to support the TCP/IP protocol. It also supports connectionless via a mode setting command from processor 20.
• protocol layers implemented in the COM Port (e.g. TCP/IP/Ethernet as in RFC 1006), these protocol layers are hidden, so that the object appears to its users to be a simple serial port.
• COM_Application subclasses define the higher levels of the specific protocols. There may be several operating system interface (OSI) layers defined in a COM_Application object, depending on the specific protocol to be implemented.
• OSI operating system interface
• the COM_Application and COM_Port classes are written in software in a manner that allows any application to be used on any port.
• certain protocol types can be provided as a separate communications library with its own protocol stack, which can thus be implemented as a COM_Application class that does not connect to a port.
• Each COM Port object attaches itself to a COM Application object whenever a protocol is designated (in the settings) for the port. In the process, it identifies itself to the COM_Application object so that there is a cross-reference between the two objects.
• the COM_Application object can therefore use functions in the COM_Port class, and vice-versa.
• the COM Port communication class includes the following subclasses:
• COM_ComlPort (which communicates on COM1 RS485); COM_Com2Port (communicates on COM2 RS485); COMJJdpPort (communications using UDP sockets); COM TcpPort (communications using TCP sockets, as described in RFC 1006); and COM_RS232Port (communicates on an RS232 serial port).
• COM_Application class includes the following subclasses: COM_Modbus Application (Modbus protocol); COM_Dnp Application (DNP protocol); and COM MmsApplication (MMS protocol).
• FIG. 7 is a diagram that illustrates the protocol layering in a relay; that is, the layers of the COM_Application class.
• the microprocessor 20 can configure the ports 16 as Ethernet ports or physical serial ports, and the microprocessor 20 can also configure the relay to communicate over the configured physical ports 16 according to MMS, Modbus, or DNP 3.0. It will of course be appreciated that the present invention is not limited to the implementation of the specific communications protocols shown in FIG. 7, and that the principles of the present invention can be applied to other communications protocols.
• FIG. 8 an illustration of the top-level data flow in and out of the communication subsystem of the relay (that is, within or under the control of the microprocessor 20) of FIG. 5 is shown.
• the processes in this diagram are further decomposed in the sections corresponding to the base classes (COM_Application and COM_Port), and further yet in the sections for the subclasses.
• the "event signals" flow can include the following specific signals: Rx Frame signal, Tx Done signal, timeout signal, and connection signal.
• the relay receives current transformer and voltage transformer samples (at, e.g., 64 samples per power system cycle) from current transformer and voltage transformer inputs 22.
• the samples are processed in digital signal processor 24, which performs fundamental calculations of power system parameters, such as phasors, frequency, RMS values, etc., and which performs current and voltage signal acquisition and calibration.
• the DSP 24 exchanges various data with the microprocessor 20 (which can be, in one implementation, a PowerPC 860 microprocessor), such as DSP firmware, configuration data, sample & hold data, oscillography samples, etc.
• the processor 20 provides protection and control of the associated power system, programmable logic, metering, event recording, oscillography, and other appropriate functions.
• the microprocessor 20 provides digital output data to digital outputs 26, and received digital input data from digital inputs 28.
• the microprocessor 20 further receives synchronization signals, such as those according to the well-known IRJG-B standard from a time code generator 30, can communicate with an external personal computer or a supervisory control and data acquisition (SCAD A) system 32 using the Modbus or DNP protocols via the RS485 or Ethernet communications ports 16, and can also communicate with remote input/output modules 34 via the RS485 port 16.
• the remote input/output modules can be other protective relays connected to a communications network.
• the relay 20 further includes a user interface panel processor 36 that receives user data via an input keypad 38, and provides the user data to the microprocessor 20.
• the user interface panel processor 36 also receives display and LED control data from the microprocessor 20 and displays this data to the user via LEDs 38 and alphanumeric display 40.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Emergency Protection Circuit Devices (AREA)
• Communication Control (AREA)
• Small-Scale Networks (AREA)
• Data Exchanges In Wide-Area Networks (AREA)

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• 2000
  • 2000-02-11 MX MXPA00009928A patent/MXPA00009928A/es active IP Right Grant
  • 2000-02-11 JP JP2000599109A patent/JP2002537746A/ja not_active Withdrawn
  • 2000-02-11 BR BR0004792-9A patent/BR0004792A/pt not_active IP Right Cessation
  • 2000-02-11 PL PL00343760A patent/PL343760A1/xx unknown
  • 2000-02-11 CN CNB008005621A patent/CN1311602C/zh not_active Expired - Fee Related
  • 2000-02-11 CA CA002326396A patent/CA2326396A1/en not_active Abandoned
  • 2000-02-11 KR KR1020007011163A patent/KR100716357B1/ko not_active Expired - Fee Related
  • 2000-02-11 EP EP00917624A patent/EP1072076A1/en not_active Withdrawn
  • 2000-02-11 WO PCT/US2000/003417 patent/WO2000048282A1/en not_active Ceased
  • 2000-02-11 AU AU38574/00A patent/AU773185B2/en not_active Ceased

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