IN
V N
N
PGN
E
V N
N
ห้องสมุดไป่ตู้
C
jX d IN
A
I N
QGN
P-Q极限
Q
QGN SGN sin N PGN tg N
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其它无功电源(Other sources of reactive power)
同步调相机 Synchronous condenser
QL QT Ql QB
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4.无功平衡与电压水平的关系
Voltage levels and reactive power balance
The control of voltage levels is accomplished
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0 ~16 时
B负荷点
VOB VB VB (0.95 ~ 1.05)VN 0.01VN (0.96 ~ 1.06)VN
16~24 时
VOB VB VB (0.95 ~ 1.05)VN 0.03VN (0.98 ~ 1.08)VN
by controlling the production,absorption and
flow of reactive power .
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4.无功平衡与电压水平的关系
Voltage levels and reactive power balance
E V I jX
overexcited----supply reactive power
underexcited-----absorb reactive power
静电电容器 Capacitors
静止补偿器 SVC---Static var compensators
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Q
0.8
jX m I V 0
I
s
I
R s
0.6
0.3
0 0.7 0.8 0.91.0
V
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无功损耗 (1) 变压器的无功损耗 Reactive power absorbed by transformers
QLT Q0 QT S 2 2 V BT ( ) X T V 与电压 I0 % VS % S 2 VN 2 SN ( ) 成正比 100 100S N V
Absorption of reactive power
2.无功电源 Production of reactive power 3.无功平衡
The reactive power balance
4.无功平衡与电压水平的关系
Voltage levels and reactive power balance
(5-16)
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调压措施 Methods of voltage control
PR QX Vb (VG k1 V ) / k2 (VG k1 ) / k2 VN
(1)发电机调压 调节励磁VG
The generating units provide the bassic means of voltage control;the automatic voltage regulators
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5.3 电力系统的电压调整
voltage control of power systems
1. 电力系统允许的电压偏移voltage deviation
3.无功平衡 The reactive power balance
QGC QLD QL Qres Qres>0 无功可以平衡,且
有备用 无 功 电 源 无 功 负 荷 无 功 损 耗 无 功 备 用 Qres<0 无功不足,应加补 偿装置
QGC QG QC QG QC1 QC 2 QC 3
与电压 成反比
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(2) 线路的无功损耗 Reactive power loss of transmission lines Production and absorption of reactive power On transmission lines
±5%
±7% +5%~ -10% +7.5%~ -10%
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2.中枢点的电压管理 中枢点key junction bus
（1）大型发电厂的高压母线(多回出线）
（2）枢纽变电所的二次母线；
（3）有大量地方性负荷的发电厂母线。
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E
V jX I
P+jQ
PLD+jQLD
Q
1' 1
2'
c
a
2
2 EV 2 V Q ( ) P2 X X
V'a Va
‘
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2.中枢点的电压管理
acceptable limints of the voltage at the key juncation terminals
中枢电压允许变化的范围
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2.中枢点的电压管理
第五章 无功功率和电压调整
Reactive power and voltage control
1.电压调整的必要性 Essentiality of voltage control/regulation 2. 无功平衡与电压水平的关系 Voltage levels and reactive power balance 3.电压调整的范围及方法
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1.无功负荷和无功损耗
无功负荷
Reactive power
jX
与电压 成正比
Reactive power absorbed by equipments
与电压 成反比
V2 QM Qm Q I 2 X Xm
V
2R(1－s)/s=常数 P = I Absorbed by loads M
4. 发电机和变压器调压 Controlling voltage levels by generating units or transformers 5. 无功功率补偿 Reactive power compensation 6. 电力系统无功功率的最优分配 Optimal allocation of reactive power
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2. 无功电源
发电机
Synchronous generators can generate or absorb reactive power depending on the excitation
过励磁 overexcited---supply reactive power
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Vo 1.025VN
小负荷时允许中枢点电压高些
Vo 1.075VN
常调压：任何负荷下，中枢点电压基本
保持恒定， (1.02-1.05)VN
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3.电压调整的基本原理
Fundamentals of voltage control
PR QX Vb (VG k1 V ) / k2 (VG k1 ) / k2 VN
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(b)向多个负荷点供电的中枢点 以两种极端情况确定： （1）地区负荷最大时，电压最低的负荷点
max Vo min V j min Voj
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