power quality and safety -...

Stronger transmission for a stronger nation.

POWER QUALITY AND SAFETY

Date : November 27, 2015

Venue : 40th IIEE Annual National

Convention and 3E XPO 2015


PRESENTATION OUTLINE

Power Quality

I. INTRODUCTION

II. GRID CODE REQUIREMENTS

III. ERC RESOLUTION No. 9 Series of 2012

IV. POWER QUALITY MONITORING ISSUES


Stronger transmission for a stronger nation. 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.



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).



I. INTRODUCTION

Ultimate reason for interest in power quality

is Economic Value



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.



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.




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




Frequency Variation

a) Normal Frequency - 60Hz

b) Maintain Frequency during Normal Conditions

c) Limits: 59.4Hz ≤ f ≤ 60.4Hz




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




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.




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.




Voltage Fluctuation

a) Flicker Severity

b) Short Term Flicker Severity (PST) – short duty cycle

fluctuation computed over a 10-minutes period.

c) Long Term Flicker Severity (PLT) – long and varaible duty

cycle and is derived for the PST levels.

d) Limits for 115kV rated systems and above: PST ≤ 0.8 units

& PLT ≤ 0.6 units.

e) Limits for below 115kV rated systems: PST ≤ 1.0 units & PLT

≤ 0.8 units.



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 115-230kV 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%.




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 115-230kV rated systems: TDD ≤ 2.5% with


• Limits for 69kV rated systems: TDD ≤ 5.0% with






Voltage Unbalance

a) Refers to negative sequence unbalance factor and zero

sequence unbalance factor.

b) Limits is set to Unb (-/0) ≤ 1.0%.

negative sequence components of voltagesNegative Sequence Unbalance Factor

positive sequence components of voltages

zero sequence components of voltagesZero Sequence Unbalance Factor

positive sequence components of voltages



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.



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.




What to monitor?

Where to monitor?

When to monitor?

How long to monitor?

What device to use for monitoring?

Acceptability Criterion?




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.



PRESENTATION OUTLINE

Safety

I. INTRODUCTION

II. INTER-RELATIONSHIP OF SAFETY AND POWER QUALITY

III. BEST GROUNDING PRACTICES FOR SAFETY AND POWER QUALITY



I. INTRODUCTION

“SAFETY IS EVERYBODY’S

RESPONSIBILITY”



I. INTRODUCTION

COMPLIANCE TO REGULATION

• Occupational Safety and Health Standards

•Fire Code of the Philippines

•Philippine Electrical Code

•Philippine Grid Code



I. INTRODUCTION

GENERAL REQUIREMENT FOR GROUNDING AND

BONDING

• Electrical Systems

•Electrical Equipment

•Bonding of Electrically Conductive Materials and other

Equipment

•Fault Current Pat Performance




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)




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



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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