Design Of On-Load-Tap-Changer Controller Based On PLC

In the modern industrial production, the requirement for system voltage quality is higher and higher, and the stable continuous power supply is one of the most basic requirements. But, due to the change of the system load, the system power supply often fluctuates. Seriously, it can even affect the normal operation of electric equipment and the enterprise production. Transformer voltage regulation is a traditional method of voltage regulation. On-load tap changer (OLTC) is the important component of on-load tap changing transformers. It can maintain the stability of voltage by adjusting the tap position without interrupting the load current. The controller of OLTC is the most important component of the on-load tap changing transformers system. Its reliability and security can decide the quality of output voltage of transformer, and then directly influence the reliable operation of on-load tap changing transformers system.Programmable Logic Controller (PLC) is used as the on-load tap-changer controller in this paper for its powerful functions. With and the communication interface, PLC has the very good ability of extension and communication. To make control more convenient and flexible, PLC is connected with TD400C text display. It can visualize the status of control system, and realize accurate parameters setting. First, the system structure diagram is introduced in this paper. The PLC and extension module is selected, and text display is configured. On this basis, the detection circuit of voltage zero point was designed, in order to achieve the requirements of synchronous control.In software design, the realization of each module function is introduced. To meet the requirements of the synchronous control, the static and dynamic simulations of permanent magnet actuator (PMA) are carried out in this paper. The experimental results of permanent magnetic actuator show that the dynamic characteristics of PMA are stable for the OLTC action. The capacity and the switching reliability of the vacuum OLTC are remarkably enhanced.Through debugging of prototype, it shows that the system meet the design requirements well, and it can realize automatic and synchronous control of on-load tap-changer.