With The Grid Line Speed Cut Protection

As we all know, the rapid movement of relay protection device and the rapid removal of electrical equipment failures can improve power system transient stability and reduce the damage to equipment and the loss effectively. So, in the power system of 220kV voltage level and above, such relay protection device with the function of full Line High Speed as the high-frequency protection, microwave transmission line protection or differential protection are generally used as the main protection. In the power network of 110kV voltage level and below, especially in the low voltage distribution system of 35kV voltage level and below, traditional three-stepor two-step current relay protection, the current and voltage interlock protection and distance protection have beenusually used during the past years because of the technology,investment and the traditional factors. In this way, only part of failure segment could be removed quickly, others part would be removed after 0.5 seconds or longer delay. With the development of electric power industry, the configuration of low voltage distribution network, the nature of load and the demand to the power quality of users, have changed much. So traditional three-step current protection encounters some practical problems. This paper will analyze these problems, bring forward the necessary of quick-trip protection and discuss the feasible technology scheme.This article will contrast different kinds of protections, such as the non-communication protection, adaptive current protection and pilot differential relay protection, find their virtue and disadvantage, through which we will find that the non-communication protection and the adaptive current protection have no good effect in practice, so in this article the pilot differential relay protection will be put into use.We will study the arithmetic of pilot differential relay protection and use it in low voltage distribution lines, then the protection criterion will be presented, based on which, the paper will bring forward the structure and the configuration of both hardware and software. At the same time, we must meet the requirements of the project, so the paper presents a simplified, economical and reliable program scheme. Then we make the reliability experiment and get the desired results.At last, under the premise of meeting the experiment request, to satisfy the request of the practical project, the paper puts forward a new communication scheme via wireless channel. This paper designs a broadcasting station communication interface circuit using the SCM technology, does much work in the hardware configuration and software design, which makes the device satisfy the practical demand and achieves good results in practice.