| Calculating settings of relay for main equipment is an important part of applying protection in power plants. Appropriate settings are necessary for relay devices to operate normally, no matter the type of relay is electromagnetic, rectification, transistor, integrated circuit and microprocessor or digital based. Even though the principles of protection, arithmetic of software and hardware design are excellent, the stability of power system and security of main equipment will be affected by improper settings when the fault occurs. Some glide of calculating settings for main equipment has been put forward in the past several decades of years. With the application of new principles and arithmetic of protection, available methods of calculating settings need to be supplemented. On the other hand, correct operating rate of relays cm not meet the requirement of power system. So it is of theoretic and practical significance to make research on calculating settings of relay for main equipment.Relay devices of main equipment protection have no uniform criterion and the style of each corporation is distinctive. Because various types of relay devices for main equipment are applied in the field and the work of calculation is so heavy that calculating in a common method is difficult to meet the requirements. With the development of computer science and communication technology, it is possible to develop a universal setting system for main equipment protection. However, there is not a universal calculating setting system in our county, so it is practically important to develop the calculating setting system of relay for main equipment.This thesis introduces calculating settings and application of relay for main equipment. It mainly includes the following parts.1) The analysis on the calculating settings of differential protection for main equipment is made from various aspects. All differential protection for main equipment can be considered as differential protection for a component with N in ports. The effect on the restraint coefficient and the least tip restraint current by adopting different restraint current is discussed. Latter, it is analyzed how to calculate the least trip differential current settings of differential protection for transformer and generator-transformer unit and how to choose the basic side of multi-side differential protection.2) This thesis analyzes the methods of calculating settings of ground protection, loss of field and out-of-step protection and over-current or overload protection etc. for generator and transformer and the difference among them is also discussed. It is pointed out how to realize the formulae of relay settings in practice, which are used universally and have advanced principles.3) Connection and setting for directional element in main equipment protection is in confusions. So one study is made on connection and interior angle setting of power directional element in main equipment protection. Connection selecting another side voltage and interior angle setting of power directional relay are analyzed when the protection is taken as the back-up protection of both line and transformer. Various constructive conclusions on the best connection and interior angle setting areachieved especially for power directional element at high and middle voltage side and they cm meet the requirements of the power system. A better connection for digital protection is also proposed, which make interior angle setting easy and can be regarded as references for field application.4) As calculating setting lags behind, on the basis of the analysis of calculating setting for main equipment protection, universal calculation setting system for main equipment protection has been designed, and development is finished partially. The system construct, technical features and development environment etc are introduced, and a method of combining emulator with setting is brought forth, which makes the sensitivity checking better. Examples using the calculation system are given in the end. |
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