Development of a Shaft Generator System without Output Voltage Distortion

轴发电机系统通过使用主机产生的部分功率来向船舶中的电子设备提供足够的功率。传统类型的这种系统的缺点是在输出电压波形中涉及大量的谐波。介绍了一种新颖、简单、无输出电压失真的轴带发电机系统。该系统采用双电抗器来抵消同步补偿器的次暂态电感。在此基础上讨论了系统的稳态特性，结果表明，当采用双工电抗器时，为了获得较大的系统输出，应增大逆变器直流输入电压和同步补偿器端电压，以保持输出端电压恒定。文中还提出了一种抑制这些电压升高的简单方法。实验研究证实了该系统的有效性。建立了轴带发电机系统的动力学模型。基于系统的等效电路，首先推导出一组暂态方程，然后得到该方程的框图表示。结果表明，该动力学模型可以用5阶非线性系统来表示。仿真了系统在直流输入电压阶跃变化情况下的暂态响应，并与实验结果进行了比较。最后对无输出电压失真的轴带发电机系统恒频恒压控制系统的动态性能进行了分析。讨论并比较了两种闭环系统在负载变化时的暂态性能，阐明了双工电抗器以及系统中的控制器常数对暂态性能的影响。

A shaft generator system feeds sufficient power to the electric apparatus in a ship by using a part of the power produced by the main engine. Conventional type of such system has a drawback of involving a large amount of harmonics in the output voltage waveform. A novel and simple shaft generator system without output voltage distortion is introduced in this research. The proposed system is equipped with a duplex reactor to cancel out the subtransient inductance of the synchronous compensator. The steady-state characteristics of the system are then discussed, and it is shown that when the duplex reactor is used, the inverter dc input voltage and synchronous compensator terminal voltage should be increased for a larger system output to keep the output terminal voltage constant. A simple method of suppressing the increase in these voltages is also proposed. The effectiveness of the proposed system was confirmed with the experimental investigations. Dynamic model of the shaft generator system is also developed. Based on the equivalent circuit of the system a set of transient equations is derived first, and a block diagram representation of the equations is then obtained. It is shown that the dynamic model can be expressed by 5th order non-linear system. Transient responses of the system in the case of a step-up change in the dc input voltage are simulated and compared with experimental ones. Finally, dynamic performances of control systems for constant frequency and constant output voltage of the shaft generator system without output voltage distortion are analyzed. The transient performances when load is changed are discussed and compared for two types of closed-loop control systems, and the effects of the duplex reactor as well as the controller constants in the system on the transient performances are clarified.