Title of Invention

SEPARATION OF PROTECTIVE AND AUTOMATION FUNCTIONS IN A PROTECTIVE RELAY FOR POWER SYSTEMS

Abstract

The invention relates to a system for maintaining separation of protection and automation functions in a single apparatus for an electric power system, comprising an apparatus for carrying out both protection and automation functions for the system} a first section (20) having a first calculating means (12) configured within the apparatus, accessible by a first password (16), for defining and performing selected protection determinations for the power system, wherein the first calculating means (12) in said first section (20) may be modified by a user having the first password (16); a second section (23) having a second calculating means (14) configured within the apparatus, accessible by a second password (18) which is different than the first password (16), for defining and performing selected automation actions for the power system, wherein the second calculating means (14) in the second section (28) may be modified by a user having the second password (18); a shared database (22) within the apparatus containing the results of operations of the first and the second calculating means (12, 14); and an area for output logic settings in the apparatus responsive to the results of the first and second calculating means (12, 14) to set outputs of the apparatus.

Full Text

Technical Field The invention relates generally to protection and automation control functions for power systems, and more particularly concerns a system for providing separation between the protection and automation functions in a single apparatus. Background of the Invention Power system substations typically include both protection and automation and control equipment and capability. Protection functions, typically implemented by various protective relays, identify and respond to faults on the power line by using voltage and current quantities obtained from the power line and processing those quantities with selected algorithms, involving the use of logic equations, to provide output control signals which, if necessary, interrupt the power by means of tripping signals. It is important to very quickly and accurately identify fault conditions, to distinguish true fault conditions from load or other system conditions, and to respond approximately, providing a tripping signal for a circuit breaker if necessary . Such action is time-critical for proper operation of a power system. Automation control functions, on the other hand, are concerned with proper functioning (operation) of a substation, including integration of its operation with the overall power system. Automation often involves exchange of information with supervisory devices but is not as critical time-wise as protection functions. Automation, in one example, involves the configuration of a substation bus. Substations include motor- operated switches, as well as circuit breakers, which may be opened or closed to achieve particular system configurations for delivery of power to the various feeders leaving the substatation. System automation includes interlocking functions which prevent the power system from using operator—initiated settings which would result in improper or dangerous bus configurations. Another example of automation is in the control (switching in/out) of various combinations of elements in the system, including for example, capacitor banks. Automation thus concerns generally substation configuration and arrangements, as well as communication with the other portions of the power system. Proper automation control requires information from more than one location within the overall power system. The automation functions and control are typically implemented with a programmable logic controller (PLC) which has a programming ability but also some significant limitations. These lmitations include lack of complete access to the status of protection elements. To include a complete access coaabillity would require a large number of contact inputs «nrt "outputs in both the protection device and the PLC. In many cases, the protection and automation functions are, accomplished by two separate, autonomous devices. Historically, this autonomy has been deemed to be desirable, because the protection and automation functions and the engineers/technicans who deal with them deal with quite different system issues and requirements. Automation efforts typically require more complex and customized logic equations to accomplish its tasks than protection efforts, while protection efforts are more focused on obtaining the required protection for the power line, with appropriate settings, and are hence more autonomous than automation efforts. Accurate protection is typically more critical to the overall system, because of the ncessity of monitoring system safety and the need for fast response to system conditions. However, increased cost is incurred with two completely separate systems, as well as system inefficiency because some system data, such as voltage and current quantities obtained from the power line, are used by both protection and automation systems. Accordingly, it would be desirable to have a single system for both protection and automation control, while maintaining the autonomy and separation between the specific control portions (logic equations) of the protection and automation functions, as well as separate output contact control in some cases. Disclosure of the Invention Accordingly, the present inventon is a system for maintaining separation of protection and automation functions present in a single apparatus such as a protective relay, used for an electric power system, comprising s a single apparatus which carries out protection and automation functions for a power system; a first section of logic equations within the apparatus, accessible by a first password, for defining and performing selected protection determinations for the power system, wherein the logic equations present in the first section may be modified by a user having the frst password, a second section of logic equations within the apparatus, accessible by a second password which is different than the first password, for defining and performing selected automation actions for the power system, wherein the logic equations in the second section may be modified by a user having the second password; a shared database within the apparatus which contains the results of the operation of the protection and automation logic equations and output logic equations in the apparatus responsive to the results of the protection and automation logic equations to set outputs of the apparatus. Brief Descripton of the Accompanying Drawing The figure shows a block diagram showing the arrangement of the combined system of the present invention. Best Mode for Carrying Out the Invention The figure s a block diagram of the system of the present invention, generally referred to at 10. System 10 forms a portion of a protective relay, which is typically located in a substation and is used to protect the operation of the power system. Protective relays vary widely in their specific purpose and capability within the power system. The system of the present invention permits the protection functions of the relay, which are controlled by logic equations, to be modified, i.e. customized, by certain users of the relay as well as permitting other users of the relay to customize the automation functionality of the substation and its system. Both protection and automation function, are accomplished by logic control equations and those functions can be modified to fit a user's particular requirement by modification of the appropriate protection and/or automation logic control equations. While the term "logic equations" is used throughout the description, it should be understood that algorithms may be used instead of logic equations, depending on the particular protective relay and its capability and other system considerations. Hence, the term "logic equations" herein should be considered to include algorithms and equivalent mathematical operations. With respect to protection, a logic equation will be used, to define and control the review of the condition of particular elements (such as circuit breaker status) as well as processing voltage and current values from the power line. These equations will be carried out on a regular periodic basis (e.g. 16 times per power system cycle) and will produce particular results. If the results fall within certain ranges, output contacts may be set and signals generated to, for instance, trip a circuit breaker. Logic equations are also used to carry out automation functions and requirements, including system configuration requirements, such as discussed above. In the embodiment shown, the protection logic equations and algorithms 12 are stored in one area in the relay, while the automation logic equations and algorithms 14 are stored in a separate area. Both sets of logic equations may be modified by trained engineers/technicans, including modifications carried out at the substation or at remote locations by means of a communication network. However, access to the protection logic equations 12 and the automation logic equations 14 are by separate, different passwords. The use of separate storage areas for the two sets of logic equations and/or algorithms, accessible by separate passwords, provides the desired autonomy for the two systems. Protection engineers will have the correct passwords to access the protection logic equations, while the automation engineers will have the correct password to access the automation logic equations. This separate accessing capability is shown by user password lines 16 and 18. Those personnel who wish to access both sets of logic equations must have both passwords. The results of the protection logic equations are stored in a first area 2O within a system database referred to at 22. Two- way access (line 24) is provided between the protection logic equations and the stored results in area 20 of database 22. This means that the logic equations can write results to area 2O, and can also obtain information from that area. The protection rogic equations 12 can change the information in area 20. The automation logic equations can obtain the information in area 2O via a read capability, shown by line 26, but cannot change or provide information to that area. Similarly, the results of the automation logic equations are provided to an automation area 28 in the system database 22. This again involves two-way communication between the automation logic equations 14 and database area 28, via communication line 29. The protection logic equations 12 can obtain information from database area 28 via line 31, but does not have the capability to write any information to that area or change any information, in that area. The protection and automation database areas, while functionally separate, are part of the single, common system database 22, thus promoting efficiency and speed of operation. Both the protection and automation logic equations do have access to system information area 30, also in database 22. System information area 30 includes analog information, such as voltages and currents which are periodically obtained from the power line, as well as other system control bits, etc., which may be applicable to both the automation and protection logic equations. As indicated in Figure 1, all three information areas 20, 28 and 3O are contained within the system database 22. It is important that both protection and automation logic equations have access to system information mica 3O. For instance, both protection and automation functions can use reactive power information. Protection uses reactive power information for various purposes, including breaker failure determination, while automation uses the same information to control the configuration of capacitor banks in the system. In another example, protection uses current values from the power line for over-current protection , while automation uses the same information for the interlockig function described above. The system of the present invention further include, an output logic equations/settings area, which responds to the information in data areas 20, 28 and 30 to configure the relay output contacts. The output contacts provide control signals which results in certain actions, such as tripping a circuit breaker etc. The output logic equations/settings, which process the results from the protection and automation logic equations, are programmable and hence can be altered by either protection, engineers or automation engineers. These output contacts can be completely separate, if desired, or the respective engineers can collaborate/consult to use a single set of output contacts. Accordingly, a system has been disclosed by which protection and automation functions can be set and controlled by separate sets of logic equations stored in different areas of a single apparatus, such as a protective relay, which thus improves overall operational efficiency, while maintaining separate, autonomous access for the two sets of logic: equations. Although a preferred embodiment of the invention has been disclosed here for purposes of illustration, it should be understood that various changes, modifications and substitutions may be incorporated without departing from the spirit of the invention, which is defined by the claims which follows. WE CLAIM 1. A system for maintaining separation of protection and automation functions in a single apparatus in communication with an electric power system, comprising: a single apparatus for carrying out both protection and automation functions for the electric power system; a first section (20) configured within the single apparatus having a first calculating means (12) accessible by a first password (16), for defining and performing selected protection determinations for the electric power system, wherein the first calculating means (12) in said first section (20) may be modified by a user having the first password (16);and the a second section (28) configured within the single apparatus having a second calculating means (14) accessible by a second password (18) which is different than the first password (16), for defining and performing selected automation actions for the electric power system, wherein the second calculating means (14) in the second section (28) may be modified by a user having the second password (18); a shared database (22) within the single apparatus containing the results of operations of the first and the second calculating means (12,14); and an area for output logic settings in the single apparatus responsive to the results of the first and the second calculating means (12, 14) to set outputs of the single apparatus. A system for maintaining separation of protection and automation functions as claimed in claim 1, comprising separate sets of outputs for protection and automation results. A system for maintaining separation of protection and automation functions as claimed in claim 1, comprising a shared set of outputs for protection and automation results. A system for maintaining separation of protection and automation functions as claimed in claim 1, wherein the shared database (22) comprises selected electric power system information area (30) which is available to both the first and the second calculating means (12,14). A system for maintaining separation of protection and automation functions as claimed in claim 4, wherein the selected electric power system information area (30) comprises power signal currents and voltages. A system for maintaining separation of protection and automation functions as claimed in claim 1, wherein the results of the first calculating means (12) are accessible by the second calculating means (14), but cannot be changed by the second calculating means (14), and wherein the results of the second calculating means (14) are accessible to the first calculating means (12), but cannot be changed by the first calculating means (12). 7. A system for maintaining separation of protection and automation functions as claimed in claim 1, wherein the output setting are carried out within the first section (20). Dated this 12th day of October, 2001 The invention relates to a system for maintaining separation of protection and automation functions in a single apparatus for an electric power system, comprising an apparatus for carrying out both protection and automation functions for the system} a first section (20) having a first calculating means (12) configured within the apparatus, accessible by a first password (16), for defining and performing selected protection determinations for the power system, wherein the first calculating means (12) in said first section (20) may be modified by a user having the first password (16); a second section (23) having a second calculating means (14) configured within the apparatus, accessible by a second password (18) which is different than the first password (16), for defining and performing selected automation actions for the power system, wherein the second calculating means (14) in the second section (28) may be modified by a user having the second password (18); a shared database (22) within the apparatus containing the results of operations of the first and the second calculating means (12, 14); and an area for output logic settings in the apparatus responsive to the results of the first and second calculating means (12, 14) to set outputs of the apparatus.

Documents:

584-cal-2001-granted-abstract.pdf

584-cal-2001-granted-claims.pdf

584-cal-2001-granted-correspondence.pdf

584-cal-2001-granted-description (complete).pdf

584-cal-2001-granted-drawings.pdf

584-cal-2001-granted-examination report.pdf

584-cal-2001-granted-form 1.pdf

584-cal-2001-granted-form 18.pdf

584-cal-2001-granted-form 2.pdf

584-cal-2001-granted-form 26.pdf

584-cal-2001-granted-form 3.pdf

584-cal-2001-granted-form 5.pdf

584-cal-2001-granted-reply to examination report.pdf

584-cal-2001-granted-specification.pdf

584-cal-2001-granted-translated copy of priority document.pdf