CAJ | 학술논문

为实现组合式三相逆变器输出电压的同步控制，该文以三台单相储能逆变器Y/△连接为例，对其离网模式及离并网预同步过程时的同步控制方法进行研究。该文在离网模式下采用基于CAN（controller area network）总线通信的基准时间同步与相位调整同步的主从同步控制方法；在此基础上，针对离并网预同步过程，该文提出了一种基于改进的二阶广义积分锁相环的频率调整同步控制方法，引入了逻辑判断控制器，实现了三相逆变器电压输出相位差时刻满足120°，保证了离网模式及离并网预同步过程时输出电压的同步，为离并网无冲击切换打下基础。最后，实际试验验证了该方法的可靠性和实用性。
위실현조합식삼상역변기수출전압적동보공제，해문이삼태단상저능역변기Y/△련접위례，대기리망모식급리병망예동보과정시적동보공제방법진행연구。해문재리망모식하채용기우CAN（controller area network）총선통신적기준시간동보여상위조정동보적주종동보공제방법；재차기출상，침대리병망예동보과정，해문제출료일충기우개진적이계엄의적분쇄상배적빈솔조정동보공제방법，인입료라집판단공제기，실현료삼상역변기전압수출상위차시각만족120°，보증료리망모식급리병망예동보과정시수출전압적동보，위리병망무충격절환타하기출。최후，실제시험험증료해방법적가고성화실용성。
The topology of three-phase inverters can divide into a three-phase bridge structure and a single-phase combined structure. Three-phase combined inverters have their own advantages compared to normal three-phase bridge inverters, such as enhanced functionality, more choices for power resources, and simple maintenance, and so on. Therefore, it is worthwhile to study the technology of three-phase combined inverters, especially the study of the synchronous control method for three-phase combined inverters. In this paper, the synchronous control method for three-phase combined inverters was studied in the island operation and the process of pre-synchronization between island and grid-connected operations based on theY/△ connection of three single-phase energy storage inverters. When in the island operation, a synchronous control method of master/slave mode through a time benchmark synchronization and a phase adjustment synchronization was proposed based on a CAN (controller area network) bus communication. With the help of a CAN bus, an automatic network was designed to determine the A, B, and C-phase for the three inverters. A synchronization frame was designed and sent every 20 ms by the A-phase inverter, which was taken as the reference phase and corrected the phase error of the sine signal, to make sure that the time benchmark synchronized and the phase adjustment synchronized .And on this basis, when in the process of pre-synchronization between island and grid-connected operations, a synchronous control method of improved PLL (phase-locked loop) through frequency adjustment synchronization and logic judgment controller was proposed based on a SOGI (second-order generalized integrator). The improved PLL added a virtual PLL compared to the traditional PLL for the calculation of the real gird voltage phase angle. And the logic judgment controller used the difference between the output voltage phase angle of the inverters and the real gird voltage phase angle as the input, which implemented the smooth handoff from the island mode to a grid-connection. The actual experiments of the three-phase combined inverters were finished to verify the proposed synchronous control methods. The controller of the inverters was developed on the popular digital processor, which is TMS320F28335 from Texas Instrument. The CAN bus baud rate was set to 125 kB/s. The reference voltage was set to 220 V, 50 Hz, and the capacity of each inverter was 8kVA. As the result, when in the island operation, the proposed method implemented the three-phase output voltages of three-phase combined inverters and always kept the phase difference for 120°, and the average of the unbalance of three phase voltage in 5 minutes was 0.4%, which is less than the specified value 1.3% and meets the standards. When in the process of pre-synchronization between island and grid-connected operations, the maximum of the unbalance of three phase voltage in 5 minutes was 2.1%, which is less than the specified value of 2.6% and meets the standards. Therefore, both in the island operation and the process of pre-synchronization between island and grid-connected operations, the results showed that the synchronous control method for three-phase combined inverters is reliable and useful.