the challenge to approve grid...
TRANSCRIPT
Grid Code requirements
• Power Quality requirements indicated in RPP Code Ver 2.9, Clause 9 and Annexure 13
• ≤ 5 MVA only require compliance certificates to prove compliance
• > 5 MVA must prove compliance as per code.
• Utility obligations as per the code
• To provide limits for the PQ parameters (apportionment)
• RPP obligations as per the code
• Prove compliance to limits via measurement and not simulation
• Prove that RPP is not exceeding the 3 x Zh ceiling
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RPP obligations
• Use a IEC 61000-4-30 class A compliant device to prove compliance.
• Compliance must be proven at the Point of Connection
• Measurement for minimum of 7 days
• Measure both voltage and current
• Power output of plant must be representative of expected output.
• Compliance must be under all network conditions
• Measure on the MV side in the case of voltage flicker and voltage unbalance.
• Compliance must be proven within 2 months of Commercial Operation date.
8 August 2017 4
RPP obligations continued
• Appendix 13 = Guideline on how to prove compliance – no deviations allowed
• Main compliance is proven via the current measurements.
• Pre and Post measurements not allowed for grid code compliance.
• No provision made for it in the guideline (Law).
• Conditions under which measurement are taken not consistent
• No or low power output is not considered to be pre measurement condition.
• CIGRE technical report 468 used for compliance methods
• Constraint =10 min aggregated rms value
• Difficult to prove direction of harmonic emission.
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Problem with Scalar values
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Vh
Eh0
Ehc
Eh0
Vh
Ehc
Harmonics being generated
Harmonics being absorbed
Problem, scalar values will is a magnitude only.
Without the angle it is difficult to say if it the emission is absorbed or generated.
Utility (NSP) expectation
• RPP to take into account PQ requirements at design stage
• Often taken into account only at the END.
• RPP are encouraged to engage with NSP regarding any potential problems that may be foreseen
• RPP’s are not taking advantage of this hence delays in the compliance process
• A detailed report to be sent to NSP
• Measurement (how, when, where, etc.)
• Assessment method employed as per Grid Code guideline
• Compliance to 3 x Zh (often left out of report)
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Utility (NSP) Challenges
• Proving that the RPP is “absorbing” or “emitting” the pollution
• Statistical method (CIGRE 468)
• Not always conclusive
• Corresponding change in voltage and current for harmonics
• Qualitative analysis
• Once direction is “proven”, tendency is to assume same behavior 24/7
• Compliance is proven at an instance in time
• Network configuration changes (taken into account by NSP)
• Impact of adjacent RPP’s
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Examples of scatter plots
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0 0.5 1 1.5 2 2.5
5th
ha
rm
on
ic v
olt
ag
e [
V]
5th harmonic current [A]
5th Voltage and Current scatter plot
5th scatter
Zh
Zhc
Utility (NSP) Challenges
• Inconsistent approaches by RPP consultants
• Report formats
• Assessment methods (some within and others outside of Grid Code)
• Turn around time of reports
• NSP not just focusing on RPP Grid Code compliance.
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