Paper Presentations

Increasing System Reliability with the Series Tuned Harmonic Filter Banks in a Chemical Facility
Byung-Ju Park, PQ TECH INC.

The results involved in the application of series tuned harmonic filter banks to reduce voltage harmonic distortion in a large chemical industry are discussed in this paper. An effective harmonic filtering of the electric power system in the chemical industry is instructed in this paper. Using of harmonic field test data, harmonic analysis, and power flow analysis studies are discussed. The problems of the power quality on the system and design factors, estimation voltage distortion between simulation and installation of harmonic filter banks are also discussed. The paper discusses various aspects of the project starting with the harmonic field test and addresses issues such as the application of the harmonic filters at large rectifier loads.

Method to Measure Harmonics in EHV Systems
Dr Forooz Ghassemi, Qualitrol Hathaway Instruments Ltd.

Power quality assessment has become an important requirement in the modern management of electricity supply systems. One aspect of power quality assessment is compliance with the international and domestic standards for harmonic pollution. These standards recommend that the frequency range of 50/60 Hz to 2.5/3.0 kHz or 50th harmonic be considered. Until now there has not been a convenient method of measuring harmonic voltages in EHV and UHV systems without the use of special, costly, voltage dividers.

Capacitor coupled voltage transformers (CVT), are the main devices used for interfacing instrumentation equipments such as meters and protection devices with Extra and Ultra High Voltage (EHV and UHV) systems. The main reason for using CVTs is the reduced cost and size compared to the conventional electromagnetic transformers. It is well known that CVTs have inferior transient and frequency responses compared to other high voltage instrument transformers. The detrimental influence of CVTs on high speed relaying is well established and has been widely reported. The Scottish grid operator, Scottish Power Plc, was concerned about the harmonic pollution that the 500 MW, HVDC link between the Scottish grid and the Northern Ireland system might cause.

A comprehensive harmonic survey was planned. The measurements were to be done by the standard instruments connected to the CVTs at a number of substations in the system. It was decided to use the CVT transfer function to compensate for the CVT errors. A new technique had to be devised to determine the CVT transfer function. This was applied to CVTs with voltage ratings of 275 and 400 kV. Furthermore, a new technique was devised and tested for accurate measurements of harmonics from CVTs. This exciting development, makes it practical to conduct continuous, system wide harmonic surveys without the need for specialist VTs and/or extensive field tests to establish compensation factors.

The new technique is based on measuring currents in CVTs and involves minimal cost and time in retrofitting to installed CVTs or in modifications during the manufacture of new units. No change in the CVT design is required and the new accessory does not affect the normal operation of CVTs. This offers a cost effective alternative to using much more costly, dedicated voltage dividers or wound VT instrument transformers which are often proposed for fast transient monitoring. The new technique offers an alternative signal to the CVT output, which is a true reflection of the CVT terminal voltage.

The experience gained in the project will be presented in the seminar.

Using the AccuSine Active Harmonic Filter to Control Harmonic Propagation Inside a Plant and Also Meet the IEEE-519-1992 Harmonic Standard
Rémi Bolduc, Schneider Electric

One AccuSine was installed in a Waste Water Treatement Plant in order to meet the IEEE-519-1992 harmonic standard.

One AccuSine active harmonic filter was installed in parallel of three 200 HP 6 pulses variable frequency drives to mitigate the harmonic at the source and meet the IEEE-519-1992. With this arrangement we can exceed the 18 pulses variable frequency drive harmonic mitigation performance at a lower cost and a smaller foot print. The AccuSine cancel harmonic on three phases network from the 2nd to the 50th harmonic regardless of the harmonic current present in the network and will also correct the power factor in real time with the extra energy it has left.

The AccuSine adjust to the load change in harmonic and reactive current with a 40 micro second response time. This rapid response allows the AccuSine to maintain the harmonic level near 5% TDD at all time and achieve dynamic var injection for power factor correction during motor start up, which in turn support the voltage during the motor inrush current.