POWER QUALITY AND SAFETY

Transcription

1 POWER QUALITY AND SAFETY Date : November 27, 2015 Venue : 40 th IIEE Annual National Convention and 3E XPO 2015

2 PRESENTATION OUTLINE Power Quality I. INTRODUCTION II. GRID CODE REQUIREMENTS III. ERC RESOLUTION No. 9 Series of 2012 IV. POWER QUALITY MONITORING ISSUES

3 I. INTRODUCTION What is Power Quality? Describes the product which is Voltage that is present at the Point of Common Coupling (PCC) or at the customer s Connection Point (CP). It describes the magnitude, frequency and waveform of the voltage that is expected at the delivery point (PCC/CP). It is important because it affects both the Suppliers and Customers.

4 I. INTRODUCTION What is Power Quality? Any power problem manifested in voltage, current or frequency deviation that results in failure or misoperation of customer equipment (R. C. Dugan et al). The concept of powering and grounding sensitive electronic equipment in a manner suitable for th equipment (IEEE Std. 1100). Set of electrical boundaries that allows a piece of equipment to function in its intended manner without significant loss of performance and life expectancy (C. Sankaran).

5 I. INTRODUCTION Ultimate reason for interest in power quality is Economic Value

6 I. INTRODUCTION Impact to Suppliers (GENCOs, TRANSCOs & DISCOs) Failure of power capacitors because of resonance condition. Increase losses in cables, transformers and transmission lines. Interference with ripple control and power line carrier system used for remote switching, load control, etc.

7 POWER QUALITY AND SAFETY I. INTRODUCTION Impact to Customers (Industrial, Commercial and Residential) Computers and communication equipment are prone to failure from power system disturbances. Automated manufacturing processes can shutdown. Induction and synchronous motors can experience abnormal heating and increase losses. Home electronic equipment are vulnerable to power quality problems.

8 II. GRID CODE REQUIREMENTS Power Quality Performance (Philippine Grid Code Article 3.2) a) System Frequency Deviation b) Voltage Magnitude Deviation c) Voltage Fluctuation d) Harmonic Frequencies e) Voltage Unbalance f) Transient Voltage Variations

9 II. GRID CODE REQUIREMENTS Frequency Variation a) Normal Frequency - 60Hz b) Maintain Frequency during Normal Conditions c) Limits: 59.4Hz f 60.4Hz

10 II. GRID CODE REQUIREMENTS Voltage Variation a) Long Duration Voltage Variation Duration greater than 1 minute. Undervoltage 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. Limits: 95% RMS Value 105% of nominal value

11 II. GRID CODE REQUIREMENTS Voltage Variation b) Short Duration Voltage Variation Duration greater than ½ cycle but not exceeding one minute. Voltage Swell RMS value increases between 110% and 180% of nominal value. Voltage Sag RMS value decreases between 10% and 90% of the nominal value.

12 II. GRID CODE REQUIREMENTS Voltage Fluctuation a) Random amplitude changes of of RMS value between 90% to 110% nominal value. b) Voltage fluctuation shall not exceed 1% of the nominal voltage for every step change, which may occur repetitively. c) Large voltage fluctuation other than a step change maybe allowed up to 3% provided it will not put to risk the Grid or any User system.

13 II. GRID CODE REQUIREMENTS Voltage Fluctuation a) Flicker Severity b) Short Term Flicker Severity (P ST ) short duty cycle fluctuation computed over a 10-minutes period. c) Long Term Flicker Severity (P LT ) long and varaible duty cycle and is derived for the P ST levels. d) Limits for 115kV rated systems and above: P ST 0.8 units & P LT 0.6 units. e) Limits for below 115kV rated systems: P ST 1.0 units & P LT 0.8 units.

14 II. GRID CODE REQUIREMENTS Harmonic Frequencies a) Total Harmonic Distortion (THD) ratio of the RMS value of the harmonic content to the RMS value of the fundamental quantity in percent. Limits for 500kV rated systems: THD 1.5% with individual harmonics Vh# odd 1.0% and Vh# even 0.5%. Limits for kV rated systems: THD 2.5% with individual harmonics Vh# odd 1.5% and Vh# even 1.0%. Limits for 69kV rated systems: THD 3.0% with individual harmonics Vh# odd 2.0% and Vh# even 1.0%.

15 II. GRID CODE REQUIREMENTS Harmonic Frequencies b) 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. Limits for 500kV rated systems: TDD 1.5% with individual harmonics Ih# odd 1.0% and h# even 0.5%. Limits for kV rated systems: TDD 2.5% with individual harmonics Ih# odd 2.0% and h# even 0.5%. Limits for 69kV rated systems: TDD 5.0% with individual harmonics Ih# odd 4.0% and h# even 1.0%.

16 II. GRID CODE REQUIREMENTS Voltage Unbalance a) Refers to negative sequence unbalance factor and zero sequence unbalance factor. Negative Sequence Unbalance Factor Zero Sequence Unbalance Factor b) Limits is set to Unb (-/0) 1.0%. negative sequence components of voltages positive sequence components of voltages zero sequence components of voltages positive sequence components of voltages

17 II. GRID CODE REQUIREMENTS Transient Voltage Variation a) High frequency overvoltages shorter in duration compared to short duration voltage variations. b) In-frequent short-duration may exceed levels of harmonic limits provided such increases do not compromise service to end-users or cause damage to Grid equipment. c) In-frequent short-duration with a maximum value of 2% maybe permitted for Voltage Unbalance subject to the terms of the Connection Agreement.

18 III. ERC RESOLUTION No. 9 Series of 2012 Requires Grid Users to monitor and submit Power Quality (PQ) Data and Report to comply with the Philippine Grid Code (PGC) requirement on Power Quality.

19 IV. POWER QUALITY MONITORING ISSUES What to monitor? Where to monitor? When to monitor? How long to monitor? What device to use for monitoring? Acceptability Criterion?

20 IV. POWER QUALITY MONITORING ISSUES Compliance with the Philippine Grid Code Compare Power Quality recorded information to limits given in the Philippine Grid Code. Apply EN50160 Acceptability Criteria Power Quality recorded indices should be within the limits given in the Philippine Grid Code for 95% of the recording duration.

21 PRESENTATION OUTLINE Safety I. INTRODUCTION II. INTER-RELATIONSHIP OF SAFETY AND POWER QUALITY III. BEST GROUNDING PRACTICES FOR SAFETY AND POWER QUALITY

22 I. INTRODUCTION SAFETY IS EVERYBODY S RESPONSIBILITY

23 I. INTRODUCTION COMPLIANCE TO REGULATION Occupational Safety and Health Standards Fire Code of the Philippines Philippine Electrical Code Philippine Grid Code

24 I. INTRODUCTION GENERAL REQUIREMENT FOR GROUNDING AND BONDING Electrical Systems Electrical Equipment Bonding of Electrically Conductive Materials and other Equipment Fault Current Pat Performance

25 II. INTER-RELATIONSHIP OF SAFETY AND POWER QUALITY Insulation faults can be traced to a) Over voltages b) Over/under frequency c) Harmonics Fault and its impact to Power Quality a) Frequency b) Voltage (Under/Over Voltage, Sag/Swell, Unbalance and Transient Variation)

26 II. INTER-RELATIONSHIP OF SAFETY AND POWER QUALITY Power Quality, which also impacts Safety, occurs as a result of inadequate or poor wiring. a) Check wiring and grounding b) Move your equipment to a dedicated circuit c) Install surge protectors d) Application of new protection technologies

27 III. BEST GROUNDING PRACTICE FOR SAFETY AND POWER QUALITY Grounding is the most important factor that governs the safety and the quality of a power system. a) Ground equipment via conductor b) Use of isolated grounding system c) Branch Circuit should also be grounded. d) Good level of ground resistance e) Use of ground rod f) Use of ground ring g) Use of an alternate grounding electrode system h) Installation of lightning protection system i) Application of surge protection device

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