Published by Electrotek Concepts, Inc., PQSoft Case Study: IEEE 519 Compliance, Document ID: PQS0321, Date: October 10, 2003.
Abstract: IEEE Standard 519-1992 is a standard that addresses the need for limiting the harmonic current a customer injects onto the utility system. It also protects the customer by specifying maximum harmonic voltage distortion levels that utilities can supply.
The installation of a 3% choke on each drive and a 150kVAr harmonic filter on the bus reduced the harmonic currents to acceptable values.
This case presents the evaluation of IEEE 519 compliance for an industrial facility supplying adjustable-speed drives.
PROBLEM STATEMENT
A wastewater treatment plant is installing five (5) 100 HP pulse width modulation (PWM) adjustable-speed drives (ASDs). The utility has specified that IEEE 519 current limits must be met.
The combined drive load has the following characteristics:
Drive Rating: 500 HP
Bus Voltage: 480 V
Fundamental Current: 600 A
SYSTEM CONFIGUATION
Figure 1 illustrates the oneline diagram used for the analysis of IEEE 519 compliance.
Short circuit and load information:
ISC(short circuit) = 26750 Amps @ 480 Volts
IL(maximum average demand load current) = 1200 Amps
ISC/IL (low side PCC) = 22
IEEE 519 CURRENT LIMITS
IEEE Standard 519-1992 is a standard that addresses the need for limiting the harmonic current a customer injects onto the utility system. It also protects the customer by specifying maximum harmonic voltage distortion levels that utilities can supply. The standard should be used for guidance in the design of power systems with nonlinear loads. Table 1 summarizes the current requirements.
Table 1 – Current Limits for Individual Customers (120V – 69kV)
where:
SCR: ratio of the short circuit current at the point of common coupling to the maximum average demand load current (Isc/Iload)
TDD: Total Demand Distortion, current distortion in percent of the maximum average demand load current
IEEE 519 defines the point of common coupling (PCC) as: A point of metering or any point as long as both the utility and the customer can either access the point for direct measurement of the harmonic indices meaningful to both or estimate the harmonic indices at a point of interference (POI) through mutually agreeable methods.
LOAD CURRENT EVALUATION
Table 2 summarizes the current requirements for the initial case with no harmonic current reduction. This evaluation illustrates the need for harmonic current mitigation. As can be seen in the table, most of the individual harmonic currents and the total demand distortion are exceeded for this case. In addition, the bus voltage distortion of 9.8% is higher than the generally accepted limit of 5%.
The transformer impedance can be determined from:
Ztx(Ω) = (kV2 / MVA) * Ztx(%) = (0.4802 / 1.5) * 6% = 0.0092Ω
The harmonic voltages are determined by multiplying the current injection times the impedance at each harmonic. The maximum average demand load current is used to scale the individual harmonic currents for comparison with the specified limits.
Table 2 – Evaluation of Current Limits for Base Case
Note: Id is based on the average maximum demand load current
MITIGATION TECHNIQUES
Several techniques for reducing the harmonic current were evaluated:
1. Installation of a 3% choke on each drive (refer to Figure 1 for new current waveform)
2. Installation of a 3% choke and a 30kVAr, 5th harmonic filter on each drive
3. Installation of a 3% choke on each drive and a 150kVAr, 5th harmonic filter on the 480 volt bus
Table 3 summarizes the results from the computer simulations.
Table 3 – Evaluation of Current Limits for Various Solutions
SUMMARY
IEEE Standard 519-1992 is a standard that addresses the need for limiting the harmonic current a customer injects onto the utility system. It also protects the customer by specifying maximum harmonic voltage distortion levels that utilities can supply.
The installation of a 3% choke on each drive and a 150kVAr harmonic filter on the bus reduced the harmonic currents to acceptable values.
REFERENCES
IEEE Recommended Practice for Electric Power Distribution for Industrial Plants (IEEE Red Book, Std 141-1986), October 1986, IEEE, ISBN: 0471856878
IEEE Recommended Practice for Industrial and Commercial Power Systems Analysis (IEEE Brown Book, Std 399-1990), December 1990, IEEE, ISBN: 1559370440
RELATED STANDARDS
IEEE Standard 519-1992
GLOSSARY AND ACRONYMS
ASD: Adjustable-Speed Drive
DPF: Displacement Power Factor
PCC: Point of Common Coupling
PF: Power Factor
PWM: Pulse Width Modulation
POI: Point of Interference
SCR: Short Circuit Ration
TDD: Total Demand Distortion
THD: Total Harmonic Distortion
TPF: True Power Factor
For the updated IEEE Standard 519-2022: IEEE Standard 519-2022 Update and Changes From Prior Version (-2014)
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