A SYSTEM APPROACH TO THE DESIGN OF AN INTEGRATED MICROPROCESSOR-BASED SUBSTATION CONTROL AND PROTECTION SYSTEM

The major problem area discussed in this paper is related to the system design of an Integrated Microprocessor-Based Substation Control and Protection System. The overall research approach is discussed first. Relevant problems related to the power system apparatus are then outlined. An extensive discussion is given of the microprocessors, software and communications to be used. A detailed analysis of the digital protection algorithms and systems is presented. Some basic implementation requirements for a digital relaying algorithm are also discussed. Digital substation data acquisition, control, and protection systems are analyzed. Finally, design specifications for an Integrated Microprocessor-Based Substation Control and Protection System are defined. The discussions are completed by giving some concluding remarks and identifying possible areas of a future research.;The research approach used in the paper is the system approach. The methodology of the approach is outlined, as well as the theory as the used for the conceptual analysis. The proposed concept is based on the hierarchical, multi-level system theory.;The specific power apparatus problems identified and analyzed are related to the power transmission lines, instrument transformers, power transformers and the substation electrical environment. Transmission Line transients analysis is given first. Behavior of an iron core current and voltage transformer is also discussed and some other types of instrument transformers are introduced. Power transformer faults, monitoring and exciting and inrush currents characteristics are also studied. Sources of the electromagnetic interference are identified and discussed.;An extensive study of the microprocessor hardware and software is given. Microprocessor architectures are analyzed and multiprocessor and multicomputer systems are defined. High level languages for microprocessor applications are considered. Pascal programming language is proposed as an attractive solution. Communication protocols and fiber optic technology are also discussed.;Digital protection algorithms are classified and compared to the conventional relaying schemes. An overview of the digital algorithms for lines, transformers, buses and generators is also given. Digital implementations of some functions closely related to the digital relaying are discussed. An analysis of the design philosophies for the digital relaying systems is also presented.;A differential equation line protection algorithm is selected to demonstrate some implementation requirements. Input/output subsystem requirements, as well as the algorithm functional requirements are indicated. Overall protection system time delay is studied and the computer program implementations are discussed.;A detailed analysis of the various implementations of the individual data acquisition and control functions is presented. Integrated data acquisition systems and SCADA systems are studied. Several integrated control system prototypes are surveyed. Proposals for an Integrated Control and Protection system are compared and a prototype system is discussed. The functional specifications for an Integrated Control and Protection System are finally outlined.;Design specifications for the proposed Integrated Microprocessor-Based Substation Control and Protection System are defined by giving an analysis of the functional specifications. System architecture and algorithms are outlined and the hardware, software and communication requirements are given. System design evaluation is then performed.;Finally, the conclusions about system advantages and disadvantages are presented. Some areas of a future research are also indicated.;An extensive, classified bibliography for the general problem area is given at the end as an addition to the regular reference list.