说明：  自己利用PSCAD搭建的２种PPL锁相环，能够自己调节ＰＩ参数，并与自带的ＰＬＬ进行了测试比较。
(PSCAD build their own use two kinds of PPL phase-locked loop to adjust the PI parameters of their own, and with the built-in PLL more)