In view of the backup protection delay of regional hub 220kV transformer external fault exists beyond the allowed thermal stability running time in rules of transformer external fault.The protection scheme of 220kV main transformer protection increasing according to the special configuration of impedance principle is reaearched and proposed,in order to shorten the transformer backup delay to meet the thermal stability limit demand.solve The problems of difficultly matching with line distance protection which applies the flow scheme of conventional increasing speed limit is solved.The setting strategy of transformer impedance protection is analyzed.The example shows that the expected effect of the scheme in practice has achieved the protection coordination with each other,to meet the thermal stability requirements for the main requipment protection.

The whole process calculation about medium and low voltage side bus parameters for 220kV step-down substation with manual calculation examples is completed,which tests all link integrity in the calculation process of 220 kV substation bus impedance parameters by using software.The effective manual calculation method is provided for verifying the reliability of software.This method can make technicians have the controllability in preliminarily applying setting calculation software and make new breakthroughs in theoretical calculation techniques of 220 kV voltage degree for region scheduling setting personnel.

In the lab report of zero-sequence impedance measuring parameters of the 220kV transformer,using the specific algorithm to achieve the whole process of its zero-sequence parameters of 220kV three-cell transformer with hand calculation example,to provide a new effective method.This method is suitable to actual parameters and replace the original experience algorithm,so the accuracy of zero-sequence impedance calculation of transformer is enhanced.

The application and running of advantages and disadvantages of switch protection under electromagnetic ring net mode are analyzed by quoting the calculation 110kV electromagnetic ring net swim distribution.The setting principle are also discussed.

In view of the practical application of microprocessor-based motor protection,the protection of functional description and the specific setting calculation are analyzed.The characteristics of induction anti-time limit of motor protection existing defects in the application are put forward that new PC should be equipped with a large motor protection to meet production demands.

The development of power system relay protection technology in our country is reviewd,and the achievement of relay protection technology is also demonstrated,The future of relay protection technology is presented such as computer,network,integration of protection,control,measurement,data communication and artificial intelligence.

The current microprocessor protection is discussed and the key processes of function maintenance are also set forth.Enhancing theory of microprocessor protection can exert superiority of microprocessor protection and protect power network really.

利用实时采集数据针对一起110 kV降压变压器短时严重过负荷后其高压侧复合电压闭锁过电流保护误动作事件,运用相量合成法、对称分量法定量计算过负荷状态中保护元件动作量,明确分析出高压后备保护误动原因,并提出技改建议.

接有并网小电源的主系统在主供电源消失时,并网小电源一定要迅速可靠地解列.但由于系统特殊的运行状态或小电源自身的一些不可预知因素,导致它不能够及时自行解列,影响电网的安全稳定运行.因此,全面考虑各种可能发生的情况,石嘴山供电局在接有并网小电源的主网终端变电站装设了故障解列装置,并详细介绍了该装置的保护性能.