zlx电力工程标幺值.ppt

zlx电力工程标幺值.ppt标幺值标幺值Per-Unit ValuePer-Unit Value内容提要内容提要?标幺值的定义?基值的选取?标幺值的优点?标幺值的缺点基本概念基本概念定义:基值的选取:取各物理量的额定值。基值实际值标幺值=相对值基值的选取基值的选取I2b=I2NI1b=I1N电流U2b=U2NU1b=U1N电压二次侧一次测基值NNNNIIIUUUIIIUUU22*222*211*111*1,,????阻抗的基值阻抗的基值NNbNNbIUZIUZ222111??二次侧:一次侧:NNbNNbUIZZZZUIZZZZ22222*211111*1????NNbNNbUIRZRRUIRZRR22222*211111*1????NNbNNbUIXZXXUIXZXX22222*211111*1??????????功率的基值功率的基值NbSS?2*22*2*22*12*1*12*22*22*21*11*11*1,,,,,QPSQPSSQQSPPSSSSQQSPPSSSNNNNNN??????????标幺值的优点标幺值的优点11▲▲*0*~~??IZk1*2*2*1*1????NNNNUIUI各物理量额定值的标么值为1与变压器容量大小无关标幺值的优点标幺值的优点22▲▲简化计算简化计算????sinsincoscos**??????NNNNNNNNNNSSSQQSSSPPkxkkrkkNNkbkkuXuRuUIZZZZ?????**111*,同理:**2*******1*1kkkkkkkkNkPIPRUIUZII??????如果加额定电流:短路实验时,标幺值的优点标幺值的优点33▲▲无需归算无需归算*22222121211*121/1UUUUUkUUUkUUUUUUbNNNb???????:例??*2222222222221112112211*121/2RZRUIRUIURkUIURUIRkZRRRRbNNNNNNNNNNb????????:例同一物理量,归算前后标幺值相等。标幺值的优点标幺值的优点44▲▲三相系统的线、相标幺值相三相系统的线、相标幺值相等等*1*331??????UUUUUUUUUUYNNNlll?????接,:例**332??????IIIIIIIIIINNNlll??????接,:例**cos3cos333??????????????PSPIUIUIUIUSPPPPNNNNNN??????:三相对称系统,例