Monitoring Software Design of Passive Dynamic Filter

Abstract

The objective of this work is to design the passive dynamic filter monitoring software. Recently, more and more non-linear loads are connected to the power grid, the distortion of the voltage or current waveform is caused by the serious harmonic pollution. The power harmonic not only does harm to the power electronic devices but also increases the power loss. Therefore, the passive dynamic filter has been developed by the author. Based on the hardware structure of the passive dynamic filter, the monitoring software of the passive dynamic filter is designed. The following works have been done in the study: control requirements of the monitoring system, component diagram of the passive dynamic filter monitoring software, program design of the monitoring software. This monitoring software has been used in the DCS of the passive dynamic filter. Introduction In recent years, with the development of electronic technology and the expansion of the industrial application, more and more non-linear loads are connected to the power grid. The content of harmonic is increasing and the power quality has fallen dramatically. In public power system, the harmonic can cause the overheating of electrical devices, the increase of power lose, and affects their operations. To eliminate the harmonic in the power grid, the passive dynamic filter has been developed by authors [1]. Compared to the active power filter, passive dynamic filters have a lot of advantages, such as simple structure, low investment of equipment, higher reliability, easily maintain and widely used [2]. This filter is mainly consisted of variable reactor (KL), IGBT of trigger circuit and filter capacitor [3][4]. According to the control requirements of the passive dynamic filter, the passive dynamic filter monitoring software (PDFMS for short) is designed by the author. The following works have been done in the study: control requirements of the monitoring system, component diagram of the MSPDF, program design of the monitoring software. Control Requirements of Monitoring System The passive dynamic filter monitoring software is designed by the modularized programming design method. The DCS of the passive dynamic filter (DCSPDF for short) is designed [1]. Its structure diagram is shown in Fig.1. The DCSPDF includes smart sensor 1~n, intelligent module 1~n, main controller, host computer, analog quantity outputs 1~n, digital output 1~n, passive dynamic filter 1~n and so on. The smart sensors are connected to the main controller by RS485. The working principles of the DCSPDF are given in [1]. Based on the working principle, basic structure and working characteristic of the passive dynamic filter, the control requirements of monitoring system are as follows: Running on/off of the DCSPDF. Running on-off control of the DCSPDF mainly includes running on-off of the passive dynamic filter 1~n and the main controller. When the passive dynamic filter generates an error signal, the DCSPDF stop working. International Power, Electronics and Materials Engineering Conference (IPEMEC 2015) © 2015. The authors Published by Atlantis Press 179 Filtering the specific harmonic. A specific harmonic, such as 5th harmonic, is selected in the monitoring interface. The PDFMS generates a signal and sends it to the main controller. The compensation capacitance is calculated by the control algorithm. And then the main controller switches on the appropriate passive dynamic filters. Monitoring the current and voltage. The values and real-time graphs of three-phase voltage and current are displayed to ensure the stability and safety of the DCSPDF. Fault monitoring. The faults in the DCSPDF are detected by the PDFMS. It ensures the safety of the DCSPDF and workers. Component Diagram of the Passive Dynamic Filter Monitoring Software The PDFMS mainly consists of the program of sending and receiving data, program of passive dynamic filters monitoring, program of data displaying, program of parameters setting, program of fault analysis, program of real-time monitoring and database. Its structure is shown in Fig.2. The data of harmonics are collected by the program of sending and receiving data. The data are stored in the database. Also these data are called by the subprograms. Database systems have wide application prospects in the distributed control system. Its high throughput, high reliability, standard interfaces and rich application software make the database achieve obvious advantages in the distributed control system [5]. The database is designed by SQL. Fig.1. DCS of the passive dynamic filter Passive dynamic filter 1 Analog quantity outputs 1