Power Quality during the late 90’s PQ was dominated by Fluke and LEM Power Utilities has just started talking

about standards to be followed National Power Corporation, Meralco -

main proponents in the utility companies involved in setting up the standards

A very few manufacturing companies are aware of the need of PQ for their facilities

Power Quality in the 2000’s

More players came in (RPM, Dranetz-DMI, Hioki, EIG, AEMC, Unipower, etc)

Philippine Grid Code was published and started to be implemented (2001)

Philippine Distribution Code was published and started to be implemented (2001)

TransCo was separated from the National Power Corporation (2003)

National Power Corporation, TransCo, Meralco - became models in the PQ standardization

Power Quality in the 2000’s (cont..)

Privatization of the government owned Power Plants

TransCo became the National Grid Corporation of the Philippines (NGCP)

Models for PQ originates from NGCP and Meralco using the PGC and PDC as basis for the standards

Manufacturing facilities engineers became aware of the need to implement PM involving PQ

Grid Code PQ Requirements

Power Quality Performance (Article 3.2) System Frequency Deviation Voltage Magnitudes Variations Voltage Fluctuations Harmonic Frequencies Voltage Unbalance Transient Voltage Variations

Grid Code PQ Requirements

Frequency Variations

Nominal Frequency – 60 Hz

Maintain Frequency during normal conditions

Limits: 59.4 Hz ≤ f ≤ 60.6 Hz

Grid Code PQ Requirements

Voltage Variations Long Duration Voltage Variation

Duration greater than 1 minuteUndervoltage (RMS value is less than or

equal to 90% of the nominal value)Overvoltage (RMS value is greater than or

equal to 110% of the nominal value)95% ≤ RMS nominal voltage ≤ 105%

Grid Code PQ Requirements

Voltage Variations Short Duration Voltage Variation

Duration greater than ½ cycle but not exceeding 1 minute

Voltage Swell (RMS value increases between 110% and 180% of the nominal value)

Voltage Sag (RMS value decreases between 10% and 90% of the nominal value)

Grid Code PQ Requirements

Voltage Fluctuation Random amplitude changes of RMS value

between 90% to 110% of the nominal voltage

Voltage fluctuation shall not exceed 1% of the nominal voltage for every step change, which may occur repetitively

Large voltage fluctuation other than a step change maybe allowed up to 3% provided will not put risk to the Grid or any User system

Grid Code PQ Requirements Flicker Severity

Short Term Flicker Severity (PST) – short duty cycle fluctuation,shall be computed over a 10-minute period

Short Term Flicker Severity (PLT) – long and variable duty cycle fluctuation, derived from PST levels

Grid Code PQ Requirements Harmonics

Total Harmonic Distortion (THD) – ratio of the RMS value of the harmonic content to the RMS value of the fundamental quantity in percent

Grid Code PQ Requirements Harmonics

Total Demand Distortion (TDD) – ratio of the RMS value of the harmonic content to the RMS value of the rated or maximum fundamental quantity in percent

Grid Code PQ Requirements Voltage Unbalance

Refers to negative sequence unbalance factor or zero unbalance factor

Negative Sequence Unbalance Factor = Negative Sequence Components of Voltages

Positive Sequence Components of Voltages

Zero Sequence Unbalance Factor = Zero Sequence Components of Voltages Positive Sequence Components

of Voltages

Compliance:Voltage Unbalance ≤ 1% for 115 kV and aboveVoltage Unbalance ≤ 2.5% for 69 kV and below

Grid Code PQ Requirements

Transient Voltage VariationsHigh frequency overvoltages shorter in

duration compared to short duration voltage variations

In-frequent short-duration may exceed levels of harmonics limits provided such increases do not compromise service to End-users or cause damage to Grid equipment

In-frequent short-duration with a maximum value of 2% maybe permitted for Voltage Unbalance subject to terms of Connection Agreement

END OF PRESENTATION

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