Power Quality during the late 90sPQ was dominated by Fluke and LEMPower Utilities has just started talking about standards to be followedNational Power Corporation, Meralco - main proponents in the utility companies involved in setting up the standardsA very few manufacturing companies are aware of the need of PQ for their facilities

Power Quality in the 2000sMore 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 2000s (cont..)Privatization of the government owned Power PlantsTransCo 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 RequirementsPower Quality Performance (Article 3.2)System Frequency DeviationVoltage Magnitudes VariationsVoltage FluctuationsHarmonic FrequenciesVoltage UnbalanceTransient Voltage Variations

Grid Code PQ RequirementsFrequency Variations

Nominal Frequency 60 Hz

Maintain Frequency during normal conditions

Limits: 59.4 Hz f 60.6 Hz

Grid Code PQ RequirementsVoltage VariationsLong Duration Voltage VariationDuration 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 RequirementsVoltage VariationsShort Duration Voltage VariationDuration greater than cycle but not exceeding 1 minuteVoltage 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 RequirementsVoltage FluctuationRandom amplitude changes of RMS value between 90% to 110% of the nominal voltageVoltage fluctuation shall not exceed 1% of the nominal voltage for every step change, which may occur repetitivelyLarge 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 RequirementsFlicker SeverityShort Term Flicker Severity (PST) short duty cycle fluctuation,shall be computed over a 10-minute periodShort Term Flicker Severity (PLT) long and variable duty cycle fluctuation, derived from PST levels

Grid Code PQ RequirementsHarmonicsTotal 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 RequirementsHarmonicsTotal 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 RequirementsVoltage UnbalanceRefers 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 RequirementsTransient Voltage VariationsHigh frequency overvoltages shorter in duration compared to short duration voltage variationsIn-frequent short-duration may exceed levels of harmonics limits provided such increases do not compromise service to End-users or cause damage to Grid equipmentIn-frequent short-duration with a maximum value of 2% maybe permitted for Voltage Unbalance subject to terms of Connection Agreement

END OF PRESENTATION

THANK YOU

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