凡绍桂 段建东 孙力

Abstract：To solve the problem of synchronous generator uncontrollable voltage caused by the broken of voltage sampling PT， the high dynamic quality voltage measurement and excitation control technology was proposed. When the PT broken fault occurs， the measurement system will automatic switch from threephase measurement mode to singlephase measurement mode. To adapt to frequency fluctuation and voltage distortion， the RMS value of phase voltage was obtained by using the voltage square singlephase detection technique. However， the sampling delay caused by singlephase measurement will result in poor dynamic performance when the excitation controller has fixed PID parameters. To solve this problem， a sliding mode controller with the estimation of steady state voltage drop of generator winding was proposed. With the proposed control method， the system has high steadystate accuracy and fast dynamic performance and strong robustness to generator system model. The effectiveness of the proposed redundancy voltage sampling technique and the excitation control technique is proved by a 10 kW synchronous generator system.

Keywords：excitation controller; PT breaking fault; singlephase voltage measurement; sliding mode controller

0 引 言

中、小容量内燃发电机组如柴油发电机组，燃气轮机发电机组等被广泛用在石油钻井平台、船舶供电，海岛供电等远离市电供电场合。孤岛运行的发电机组，要求其发电机励磁控制器具有高可靠性，高稳态精度，以及较快的动態性能[1-2]。

励磁控制器的电压传感器（potential transformer，PT）断线故障会导致发电机无法正常工作，严重影响孤岛发电机组可靠性。本文提出发电机电压容错测量技术，正常情况下采用三相四线制测量模式，当发生PT断线故障时自动切换至单相容错测量模式。许多学者通过构造直角坐标系来实现单相电压测量，如积分延时T/4构造直角坐标系[3]、基于反Park构造直角坐标系[4]、采用微分构造直角坐标系[5]以及采用广义二阶积分器（secondorder generalized integrator，SOGI）构造直角坐标系[6-7]等，以上构造直角坐标系的方法需要稳定的频率信号，对于并网发电系统，电网频率基本恒定，可以采用以上方法[8-9]。而对于孤岛发电系统，发电机频率波动较大，电压畸变严重，不易采用以上单相电压测量方法。本文采用电压自平方单相检测方法，该方法对频率波动及电压畸变有较大适应性。由三相测量切换至单相测量后，单相测量带来的采样延时使经典PID调节器在不改变PID参数情况下，很难达到三相测量时的控制效果，使发电机动态性能受到较大影响。为提高励磁控制器性能，很多学者对励磁控制器进行了改进，如文献[10]设计了一种同时以机端电压、有功功率、无功……