POWER QUALITY IMPROVEMENT IN A HARMONIC ENVIRONMENT
G. N. C. Ferguson
B.Tech., LM & SS, LM.IEEE
Abstract – The effect of single-phase, nonlinear loads, as sources of positive-, negative- and third-order, zero-sequence harmonic currents in low voltage electrical distribution systems, is discussed. Various traditional methods for dealing with these harmonic currents are outlined and their shortcomings identified. Alternative methods, which provide harmonic current reduction, and power quality improvement, are presented. Results of the application of alternative devices in typical environments are given.
A paper reprint from the InterNational Electrical Testing Association (NETA) Annual Technical Conference, March 19, 1997, St. Louis, MO.
MISSION-CRITICAL SYSTEM & LOAD EFFICIENCY
G. N. C. Ferguson , B.Tech., LM & SS, LM.IEEE
Aleksandar Damnjanovic , PhD, EE
Abstract – It is understood that data centers’ mission-critical loads require absolute continuity of electrical supply and a high degree of electrical distribution system-load compatibility. However, based on a review of typical system configurations and their component and load technologies, it becomes clear that there is an opportunity for significant energy efficiency improvement.
With an ever-increasing demand for electrical energy and the prospect of ever-increasing power costs, facility stakeholders, and government regulators, are now focusing on energy efficiency improvement. The application of ultra-efficient transformers, which improve system-load compatibility, can significantly reduce the ‘penalty losses’ associated with conventional system designs.
In addition, the selection of power factor corrected switch-mode power supplies, which do not depend on the application of input capacitors to reduce harmonic current injection into the distribution system, would reduce their internal ‘penalty losses’, increase their efficiency and eliminate the leading power factor problems associated with their application.
This paper will discuss the high costs associated with conventional non-mitigating designs, alternate mitigating designs, the measurement of system losses and efficiencies under normal operating conditions, and the financial benefits resulting from harmonic current reduction and/or voltage optimization.
The Measurement and Evaluation of Distribution Transformer Losses under Non-Linear Load
Gregory Ferguson, B.Tech., LM & SS, LM.IEEE
Aleksandar Damnjanovic, PhD, EE
Abstract – Harmonic currents, generated by non-linear electronic loads, produce ‘penalty losses’ in every element of an electrical distribution system. These harmonic-related losses reduce system efficiency, cause apparatus overheating, and increase power and air conditioning costs. Harmonic currents effectively de-rate existing systems and, when accommodated, add substantially to the capital cost of new distribution systems. The measurement of transformer losses under linear and non-linear load conditions will be discussed. In addition, typical financial benefits that result from the application of harmonic mitigating distribution transformers, under non-linear loading, will be calculated.
A paper reprint from the IEEE Power Engineering Society General Meeting, Denver CO, June 9, 2004 / PESGM 2004-000721
The Costs and Benefits of Harmonic Current Reduction in Low Voltage Distribution Systems
G. N. C. Ferguson, B.Tech., LM & SS, LM.IEEE
Abstract – Harmonic currents, generated by non-linear electronic loads, produce ‘penalty losses’ in every element of an electrical distribution system. These harmonic-related losses reduce system efficiency, cause apparatus overheating, and increase power and air conditioning costs. Harmonic currents effectively de-rate existing systems and, when accommodated, add substantially to the capital cost of new systems which must be de-rated or K-Rated. The magnitude of typical ‘penalty losses’ and increased operating costs will be evaluated. The capital cost of conventional and harmonic mitigating system designs will be discussed, and the financial benefits will be calculated.
Power Quality & Energy Efficiency Improvement at the Wynn Macau, China Hotel & Casino
Gregory Ferguson, B.Tech., LM & SS, LM.IEEE
Abstract – Single-phase electronically controlled nonlinear lighting loads, connected phase-to-neutral in a three-phase, four-wire electrical distribution system, generate extremely high levels of positive-, negative- and third-order, zero-sequence harmonic currents.
Without harmonic mitigation, single voltage distribution systems, which exclude low voltage distribution transformers, are inherently unsuited as a power source for these troublesome nonlinear electronic loads. Single voltage distribution systems are common in Asia and Europe where the distribution and utilization voltage is 400/230-volts or higher.
Our technical prowess is revolutionizing the power system optimization market.
FES International fixes problems and finds energy savings that provide attractive financial returns and significantly improved operations.
What Is the Problem?
All nonlinear electronic loads generate positive- and negative-sequence harmonic currents. Single-phase nonlinear electronic loads, connected phase-neutral in a three-phase, four-wire distribution system, also generate zero-sequence harmonic currents.
Three-phase motor drives and single-phase lighting loads often account for a significant portion of a 480V system’s loads. Single-phase nonlinear electronic office loads typically account for more than 95% of a 208/120V power panel’s loads. At these levels, unacceptable levels of Total Harmonic Distortion of Current are not uncommon.
In industrial settings, the problems are further compounded by the application of variable frequency drives and induction motors. Total Harmonic Distortion of Current produces ‘penalty losses’ in every element of the electrical distribution system while Total Harmonic Distortion of Voltage produces ‘penalty losses’ in its loads. These losses reduce their energy efficiencies, increase power consumption, accelerate asset failure and impact facility productivity and profitability.
Here is an in-depth breakdown of the challenges experienced:
System Performance Issues
The injection of harmonic currents into an electrical distribution system, which is based on a non-mitigating ‘conventional design’, will normally produce the following unacceptable outcomes:
- High Total Harmonic Distortion of Current [THDI]
- High Neutral Currents
- High Harmonic Current Injection into the utility’s Point of Common Coupling (meter)
- Increased Voltage Drop in feeder circuits, bus duct risers, and branch circuits
The impact of harmonic currents on a distribution system can be quite significant. From energy unnecessarily consumed to horsepower lost within a motor, numerous issues can arise which impact system performance. When current losses are reduced, system losses are reduced as well. The net effect is financially beneficial.
To define and limit harmonic problems, IEEE published ANSI/IEEE Std 519-1992, Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems.
Power Quality Issues
In an Ohms Law relationship, harmonic currents generate harmonic voltages. These voltages normally produce the following unacceptable power quality problems:
- High Total Harmonic Distortion of Voltage [THDV] at the loads (ref. IEEE Std 519-1992)
- High Neutral-to-Ground Voltage at the loads (ref. ITIC, formerly CBEMA)
- Large Neutral-to-Ground Voltage Differentials between computers and data processing equipment, which are connected into a communications “network” (ref. EPRI)
The presence of power quality issues within the facility, while increasing energy costs, has an even greater effect on operational performance. When distorted voltage is present, significant performance degradation occurs in the loads utilized within the facility. The impact stretches from computers to large motors, HVAC, lighting, and almost all other connected devices interacting with the distribution system.
A detailed analysis of a ‘conventional design’ will normally uncover many of the following undesirable financial outcomes:
- High power costs
- High capital cost
- High ‘penalty losses’ in transformers and motors
- Low power factor
- Loss of productivity, quality, and revenue
- Shorter asset life/earlier failure
- Presence of power system issues that are challenging to define
FES International’s Process Provides Success:
FES International follows a rigorous approach to provide fully customized solutions that guarantee power quality and efficiency. Our goal is to provide highly predictable service and a positive customer experience, with a guaranteed financial benefit for every project in which we engage.
We first determine that the facility is a good candidate for power system optimization:
Technical Data Collection
The power system optimization process begins when you provide us with your facility’s single-line diagrams and 12 months of energy bills.
Initial Engineering Review
We begin by conducting a review of the single-line diagrams and analyzing utility bills, using proprietary diagnostic tools to estimate the potential savings for the facility. This review allows us to predict a potential financial benefit. There is no cost to you for the initial engineering review.
We then prepare a proposal including the costs associated with a facility audit. Based on our experience, we determine appropriate measurement sites throughout your electrical system. On receipt of your purchase order, we coordinate a site visit with your designated facility contact.
Our team then performs a comprehensive electrical audit to provide our engineers with the data they need to confirm the energy and cost savings an FES solution will provide.
Solution Pricing and Contract
Based on our audit, we evaluate the opportunity and present a power system optimization proposal. Our proposal includes a system performance and may include a financial outcome guarantee.
Engineering the Solution
After our proposal is accepted, we engineer a solution that improves power quality and energy efficiency throughout the facility.
We provide detailed specifications and installation instructions for implementation of the solution. We also provide supervision of the installation and commissioning services.
Measurement and Verification
Post-installation, we perform the necessary calculations to verify the savings. The net result: The power system itself is optimized, energy savings are immediately realized, the longevity of electrical devices is improved system-wide and operational expenses are reduced.