Environmental Engineering Reference
In-Depth Information
converters. Permissible levels of harmonic currents are defined in IEC 61000-3-2.
Utilities have established own permissible levels. Permissible values of harmonic
currents are given in A/MVA, referred to short-circuit apparent power in the point
of common connection. Regulations as defined by utilities in Germany for privately
owned systems feeding into the grid, are given separately for low-voltage [VDW05],
for medium voltage [VDEW98] and for high voltage [VDN04].
Table 7.1 gives limiting values for harmonic currents for generating systems feed-
ing into LV, MV and HV grids, respectively.
Table 7.1
Permissible harmonic currents at connecting point
Order
number
Low voltage
[VDW05]
Medium voltage,
10 kV [VDEW98]
High voltage, 220 kV
[VDN04]
ν
,
μ
A/MVA
A/MVA
A/GVA
3
4
5/7
2,5/2
0,115/0,082
1,3/1,9
9
0,7
11/13
1,3/1
0,052/0,038
1,2/0,8
17/19
0,55/0,45
0,022/0,018
0,46/0,35
23/25
0,3/0,25
0,012/0,010
0,23/0,16
ν
>
25
0
,
25
·
25
/
ν
0
,
06
/
ν
2
,
6
/
ν
ν = even
1
,
5
/
ν
0
,
06
/
ν
2
,
6
/
ν
μ
<
40
1
,
5
/
μ
0
,
06
/
ν
2
,
6
/
ν
μ
>
40
∗
4
,
5
/
μ
0
,
18
/
ν
8
/
ν
∗
integer & non-integer, in bandwidth of 200 Hz
An integral quantity characterizing the total harmonic distortion value is the
THD. Regarding currents, harmonic components up to the order 40 are considered:
40
2
I
n
2
THD
=
where
I
1
= fundamental current
(7.5)
I
1
Electromagnetic compatibility (EMC) issues are addressed in an IEC standard
[IEC60100], where IEC 61000-4-7 is a guide on harmonics and interharmonics
measurement and instrumentation. For low voltage power systems IEC 61000-3-2
defines limits for harmonic current emissions.
7.4.2 Voltage Deviations and Flicker
Grid reactions generated by a WES must be limited in such a way that the ser-
vice of equipment of other costumers and of utility devices is not disturbed. This is
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