Cheng-Ting Hsu
Department of Electrical Engineering
Southern Taiwan University of Technology
Tainan, Taiwan

Introduction
Description of Distribution Feeder
Harmonic Analysis for the
Distribution System without PVGS
Description of PVGS
Harmonic Analysis for the
Distribution System with PVGS
Conclusion

由於台灣自產能源不足及環保意識的抬頭，使
得在尖峰用電時刻電力不足。此外，為因應我
國之電業自由化，將來勢必會出現許多再生能
源發電系統及以天然氣為燃料的小型套裝氣渦
輪機。
這些分散式電源系統 (DGS) 因容量較小，故會
與電力公司之配電系統並聯運轉，對現有配電
系統之運轉與規劃會產生重大影響。
本計劃欲探討之內容包括配電系統之電壓控制
與電容器規劃、諧波、短路故障及保護協調、
孤島偵測與運轉可行性及電壓驟降等議題。
本年度之研究內容主要在分析 DGS 對配電系統
之電壓與諧波影響。

7
8
5
6
Bus P(kW) Q(kvar)
2 0 0
3
4
427
684
140
224.82
534
534
1048
406
400.5
544.79
786
196.63
9
10
11
972 857.22
408 416.24
1487 921.56

Harmonic
Order
13
14
16
17
7
8
10
11
19
20
22
23
2
4
5
25
3
1.80
1.50
3.11
2.19
0.64
0.62
1.15
1.04
0.39
0.26
0.82
0.81
0.41
0.43
0.35
0.48
4
2.14
1.39
3.16
2.23
0.61
0.53
1.15
1.04
0.34
0.24
0.82
0.79
0.36
0.39
0.39
0.50
Harmonic current generated at each bus(%)
5
1.61
1.02
3.50
2.46
0.52
0.34
1.28
1.09
0.17
0.18
0.87
0.80
0.20
0.26
0.55
0.60
6
1.33
0.82
3.40
2.38
0.48
0.21
1.19
0.98
0.06
0.15
0.80
0.71
0.10
0.18
0.57
0.60
7
1.46
0.94
1.44
2.90
0.48
0.32
1.60
1.36
0.16
0.16
1.08
0.98
0.19
0.24
0.70
0.72
8
2.18
1.42
2.96
2.08
0.63
0.56
1.05
0.95
0.34
0.24
0.75
0.72
0.36
0.39
0.34
0.46
9
1.25
0.80
4.36
3.08
0.43
0.25
1.72
1.44
0.11
0.14
1.14
1.03
0.13
0.19
0.78
0.77
10
1.88
1.22
3.61
2.55
0.56
0.47
1.37
1.20
0.28
0.21
0.95
0.89
0.30
0.33
0.53
0.60
11
1.87
1.17
4.01
2.84
0.53
0.46
1.59
1.38
0.27
0.20
1.09
1.01
0.29
0.32
0.62
0.68

利用表 2 配合日負載曲線與
自行研發撰寫之諧波潮流
程式，可算出各匯流排一
日 24 小時各級諧波失真與
等效阻抗。
執行右表中四種不同之事
例分析，由於諧波失真大
小與負載量成正比關係，
故僅列出最重載 ( 早上 11 點 )
與最輕載 ( 凌晨 4 點 ) 時各匯
流排之總諧波失真。
事
例
電
容
器
1
2
3
4
√
√
濾
波
器
√
調整 OLTC
變壓器
√
√

Case 1
0.81
4.8%
In this case study, no capacitor and filter is installed on the distribution feeder and the voltage at Bus 1 is set by 1.0p.u. without adjusting the tap changer of the transformer. The voltage drop and total voltage harmonic distortion of each bus with the heavy and light load have been simulated as shown in the above figures. It is found that the bus voltage is dropped to the minimum value of 0.81p.u. and the total harmonic voltage distortion is increased to the maximum value of 4.8% at
Bus 11 by serving the heavy load.

Case 2
A capacitor bank with a total capacity of 1500kvar is installed at Bus
10 to provide the reactive power compensation for the feeder.
However, the voltage drop are still serious for many buses by serving the heavy load. The minimum voltage at Bus 11 has been increased from 0.81 to 0.87p.u. as compared to Case 1.
0.87

Case 2
Furthermore, the harmonic voltage will be amplified due to the resonant phenomenon, which occurs at frequency of 280Hz for the heavy load. The total voltage harmonic distortion at many buses are unacceptable. It reaches the maximum value of 11.6% at bus 10.
11.6
280Hz

Case 3
Both the capacitors and OLTC transformer have been used to provide the voltage regulation of the feeder . The voltage level of all buses along the feeder can be regulated within 4% around the base voltage of 1.0p.u as shown in the below figure. The total harmonic voltage distortion will be reduced slightly during the heavy load time period because the fundamental bus voltage along the feeder has been adjusted to be higher than 0.96p.u.
8.38%
0.96

Case 4
To improve the harmonic distortion, two passive filters with turning frequency at 282Hz and 408Hz have replaced the capacitor banks to bypass the 5th and
7th orders harmonic currents. The resonant frequencies have been shifted to the values of 210Hz and 370Hz. By this manner, the total voltage harmonic distortion of each bus will be suppressed to be smaller than 1.5% as shown in the figure.
1.5%
210 370
282 408

(a) Heavy Load (9kW)
(b) Middle Load (4.5kW)
(c) Light Load (2kW)

Harmonic
Order
2
3
4
5
6
7
8
9
10
11
12
13
Heavy
Load
(%)
0.288
0.328
0.106
0.384
0.053
1.141
0.327
0.043
0.057
0.108
0.021
0.073
Middle
Load
(%)
0.341
0.309
0.109
0.338
0.033
1.153
0.071
0.046
0.043
0.118
0.053
0.037
Light
Load
(%)
0.328
0.245
0.113
0.354
0.070
1.095
0.044
0.051
0.042
0.074
0.042
0.074
Harmonic
Order
14
15
16
17
18
19
20
21
22
23
24
25
Heavy
Load
(%)
0.040
0.031
0.031
0.054
0.033
0.047
0.022
0.040
0.028
0.036
0.021
0.018
Middle
Load
(%)
0.038
0.025
0.036
0.049
0.043
0.045
0.046
0.042
0.034
0.052
0.026
0.027
Light
Load
(%)
0.051
0.047
0.041
0.058
0.052
0.067
0.032
0.028
0.056
0.036
0.016
0.044

5
6
7
8
事例 電容器 濾波器
√
√
√
√
9
√
10
√
調整 OLTC
變壓器分接頭
√
√
√
√
√
√
PVGS 容量與
發電模式
2MVA/1MW 定功率
10MVA/5MW 定功率
2MVA/1MW 定功率
10MVA/5MW 定功率
10MVA/ 功率隨
日照度變化
10MVA/ 功率隨
日照度變化

0.964
 0.978
Case 5
8.38
 8.13 %

事例 6
8.94%

Case 7
1.49
 1.46 %
0.75

0.76 %

Case 8
1.01
%
1.6
%

經本年度之計劃研究可知含交直流轉換器之分散
式電源所產生的諧波電流並不大，如經濾波器的
改善，對配電系統所造成的諧波污染亦不嚴重。
此外，分散式電源執行電壓控制可讓饋線各匯流
排的電壓獲得更佳的補償。
配電系統在離峰時發生電壓驟降較尖峰時嚴重。
配電系統裝置較大容量之分散式電源可改善電壓
驟降的現象。
未來本計劃將繼續研究分散式電源對配電系統運
轉與規劃所造成的影響，例如：短路故障及保護
協調 、 孤島偵測與運轉可行性 、 最佳電容器規劃
等議題。