Renewable Energy Integration: Power Quality Issue IV - Power Quality issues... · •Without quality power, electrical device ... Issues and their impact 25. ... •Railways has sought

Renewable Energy Integration:Power Quality IssuePower Quality IssuePower Quality IssuePower Quality IssuePower Quality IssuePower Quality IssuePower Quality IssuePower Quality Issue

Energy Integration:Power Quality IssuePower Quality IssuePower Quality IssuePower Quality IssuePower Quality IssuePower Quality IssuePower Quality IssuePower Quality Issue

Vikram Singh

Director( Grid Management)

Central Electricity Authority

Power quality

• Term ‘Power quality’ not defined in EA 2003, CEA regulations or IEGC.

• Power quality is a measure of the fitness of electrical power devices.

• “The characteristics of the electricity at a given point on an electrical system, • “The characteristics of the electricity at a given point on an electrical system, evaluated against a set of reference technical parameters

• Without quality power, electrical device (or load) may malfunction, fail prematurely. Poor quality device may pollute Grid power.

• PQ is a critical concern, inefficiency, & damages to production quality.

• success of ‘Make in India” needs high PQ standards

Power quality

’ not defined in EA 2003, CEA regulations or IEGC.

fitness of electrical power fed into the consumer

The characteristics of the electricity at a given point on an electrical system, The characteristics of the electricity at a given point on an electrical system, evaluated against a set of reference technical parameters”.

electrical device (or load) may malfunction, fail prematurely. Poor quality device may pollute Grid power.

damages to equipment, high losses, poor

needs high PQ standards

2

Power quality parameters

1. Supply : Interruptions

2. Magnitude: Sag, Swell, under and over deviation, transients

3. Frequency: Over and under frequency

4. Waveform: Harmonics, and sub harmonics4. Waveform: Harmonics, and sub harmonics

5. Phase: Unbalance

parameters

Sag, Swell, under and over deviation, transients

: Over and under frequency

: Harmonics, and sub harmonics

3

: Harmonics, and sub harmonics

Power quality Parameters considered in CEA technical Standards

Regulation 3 (a) of CEA (Grid Standards) Regulations 2010

Frequency:

close to 50 Hz and shall not allow it to go beyond the range

narrower frequency band specified in the Grid Code, except during the transient

period following tripping.

(Grid Code specifies range: 49.90 to 50.05 Hz)

Parameters considered in CEA technical Standards

Regulation 3 (a) of CEA (Grid Standards) Regulations 2010

4

to 50 Hz and shall not allow it to go beyond the range 49.2 to 50.3 Hz or a

narrower frequency band specified in the Grid Code, except during the transient

(Grid Code specifies range: 49.90 to 50.05 Hz)

Frequency ProfileFrequency ProfileFrequency ProfileFrequency ProfileSource: POSOCO



Grid Standards

S. No. Nominal System Voltage (kV

rms)

Maximum (kV

1 765

3 (1) (b) maintain the steady state voltage within the limits specified below

1 765

2 400

3 220

4 132

5 110

6 66

7 33

Grid Standards

Maximum (kV

rms)

Minimum (kV

rms)

800 728

within the limits specified below

800 728

420 380

245 198

145 122

121 99

72 60

36 30

Voltage over voltage and unbalance

S. No. Nominal System Voltage (kV rms

3 (1) ( c) ensure that the temporary over voltage

remains within the limits specified

1 765

2 400

3 220

4 132

Below 132 kV, respective SERC to decide in the respective Grid Code

Voltage over voltage and unbalance

rms) Phase to Neutral (kV peak)

temporary over voltage due to sudden load rejection

914

514

283

170

decide in the respective Grid Code

Voltage unbalance


3 (1) (d) ensure that the maximum permissible values of voltage unbalance

shall be as specified in Table below:-


rms)

1 765 and 400

2 220

3 132 to 33

Provided that Bulk consumers shall avoid unbalanced load during operation:

Provided further that the distribution licensees shall ensure that their loads are not

Nominal System Voltage (kV Voltage unbalance

) ensure that the maximum permissible values of voltage unbalance

Nominal System Voltage (kV Voltage unbalance

(%)

1.5

2

3

Provided that Bulk consumers shall avoid unbalanced load during operation:

shall ensure that their loads are not unbalanced.

Load crash of NR on 11Load crash of NR on 11Load crash of NR on 11Load crash of NR on 11

�Load crash of around 6500 MW due to rain and thunderstorm on

12.12.2017

� Punjab, Haryana, Uttar Pradesh, J&K,

�High frequency and high voltage condition prevailed.

Frequency touched 50.18Hz at 06:01hrs/12.12.2017.�Frequency touched 50.18Hz at 06:01hrs/12.12.2017.

�22 no. of 400kV lines and ICTs tripped during the period.

�54 no. of 400kV and 5 ICTs opened manually.

Load crash of NR on 11Load crash of NR on 11Load crash of NR on 11Load crash of NR on 11---- 12.12.201712.12.201712.12.201712.12.2017

Load crash of around 6500 MW due to rain and thunderstorm on

Punjab, Haryana, Uttar Pradesh, J&K, Himachal Pradesh & Uttarakhand.

frequency and high voltage condition prevailed.

at 06:01hrs/12.12.2017.at 06:01hrs/12.12.2017.

tripped during the period.

opened manually.

Source: POSOCO

Source: POSOCO

Tripping due to over voltage

On 12.12.2017 around

Tripping due to over voltage

Grid Standards: Voltage Harmonics

S.No.System Voltage (kV

rms)

Total Harmonic

Distortion (%)

3 (2) The transmission licensee shall ensure that the

maintained at all points in the Grid by observing the limits given in Table

S.No.rms) Distortion (%)

1 765 1.5

2 400 2

3 220 2.5

4 33 to 132 5

Grid Standards: Voltage Harmonics

Total Harmonic

Distortion (%)

Individual Harmonic of any

particular Frequency

) The transmission licensee shall ensure that the voltage wave-form quality is

maintained at all points in the Grid by observing the limits given in Table below,-

Distortion (%)particular Frequency

(%)

1

1.5

2

3

15

CEA(Technical CEA(Technical CEA(Technical CEA(Technical Standard for Grid Connectivity) Standard for Grid Connectivity) Standard for Grid Connectivity) Standard for Grid Connectivity) Regulations, 2007Regulations, 2007Regulations, 2007Regulations, 2007

Part-IV : Grid Connectivity Standards applicable to the Distribution Systems and Bulk Consumers

3. Voltage and Current Harmonics3. Voltage and Current Harmonics

1) The total harmonic distortion for voltage at the connection point shall not exceed 5% with no individual harmonic higher than 3%.

2) The total harmonic distortion for current drawn from the transmission system at the connection point shall not exceed 8%.

Standard for Grid Connectivity) Standard for Grid Connectivity) Standard for Grid Connectivity) Standard for Grid Connectivity)

Connectivity Standards applicable to the Distribution Systems and Bulk

The total harmonic distortion for voltage at the connection point shall not exceed 5% with no individual harmonic higher than 3%.

The total harmonic distortion for current drawn from the transmission system at the

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4. Voltage Unbalance

The Voltage Unbalance at 33kV and above shall not exceed 3.0%.

5. Voltage Fluctuations

CEA(Technical Standard for Grid CEA(Technical Standard for Grid CEA(Technical Standard for Grid CEA(Technical Standard for Grid Connectivity) Regulations, 2007Connectivity) Regulations, 2007Connectivity) Regulations, 2007Connectivity) Regulations, 2007

5. Voltage Fluctuations

1) The permissible limit for step changes which may occur repetitively

is 1.5%.

2) For occasional fluctuations other than step changes the maximum

permissible limit is 3%.

The Voltage Unbalance at 33kV and above shall not exceed 3.0%.

CEA(Technical Standard for Grid CEA(Technical Standard for Grid CEA(Technical Standard for Grid CEA(Technical Standard for Grid Connectivity) Regulations, 2007Connectivity) Regulations, 2007Connectivity) Regulations, 2007Connectivity) Regulations, 2007

17

The permissible limit for step changes which may occur repetitively

For occasional fluctuations other than step changes the maximum

CEA(Technical Standard for Grid Connectivity) Regulations, 2007: Part-II :

5) The project of the requester shall not cause voltage and current harmonics limits specified in IEEE Standard 519

B. For wind and generating station using inverter B. For wind and generating station using inverter

B1. Requirement with respect to Harmonics, DC

1.Current harmonic as per IEEE 519.

2.DC current not greater than 0.5% of full rated output at inter connection point.

3.Flicker limit as per IEC 61000

Standard for Grid Connectivity)

5) The project of the requester shall not cause voltage and current harmonics which exceed

B. For wind and generating station using inverter B. For wind and generating station using inverter

DC Injection and Flicker

DC current not greater than 0.5% of full rated output at inter connection point.

Continued

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CEA(Technical Standard for Grid Connectivity) Regulations, 2007: Part-II :

Measurement of harmonic content, DC injection and flicker shall Measurement of harmonic content, DC injection and flicker shall a year in the presence of parties concern.

Provided in addition to above if a licensee desire to measure harmonic content, or DC injection or flicker, it shall inform the other party in writing and measurement shall be carried out with in 5 working days.

Standard for Grid Connectivity)

harmonic content, DC injection and flicker shall be done at least once in harmonic content, DC injection and flicker shall be done at least once in

Provided in addition to above if a licensee desire to measure harmonic content, or DC injection or flicker, it shall inform the other party in writing and measurement shall be

19

CEA(Technical Standard for Connectivity of the CEA(Technical Standard for Connectivity of the CEA(Technical Standard for Connectivity of the CEA(Technical Standard for Connectivity of the distributed generation resources) Regulations, 2013distributed generation resources) Regulations, 2013distributed generation resources) Regulations, 2013distributed generation resources) Regulations, 2013

11. Standards for distributed generation resources

1. Harmonic Current injection from a generating station shall not exceed the limit specified in IEEE standard 519. IEEE standard 519.

2. The distributed generating resource shall not inject DC current greater than 0.5% of full rated output at interconnection point.

3. The distributed generating resource shall not introduce flicker beyond limits specified in IEC 61000.

Provided that the standards for flicker will come into effect from 1st April 2014.

CEA(Technical Standard for Connectivity of the CEA(Technical Standard for Connectivity of the CEA(Technical Standard for Connectivity of the CEA(Technical Standard for Connectivity of the distributed generation resources) Regulations, 2013distributed generation resources) Regulations, 2013distributed generation resources) Regulations, 2013distributed generation resources) Regulations, 2013

11. Standards for distributed generation resources

Harmonic Current injection from a generating station shall not exceed the limit specified in

The distributed generating resource shall not inject DC current greater than 0.5% of full

The distributed generating resource shall not introduce flicker beyond limits specified in

that the standards for flicker will come into effect from 1st April 2014.

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Network Operator (discom/transcom

: Voltage & Impedance

Customer : current

( however above relationship not straight)

Who is responsible for Power


Manufacturer/Industry : Emission &

transcom)

Voltage & Impedance

Customer : current


Who is responsible for Power Quality


Emission & Immunity

Power Quality Parameters observed 175 s/stn, 500

Quality Parameters observed ( Swachh Power report 2015), 500 feeders

Source: POWERGRID

Source: PGCIL’s Swachh Power Report (

2015)

Transmission system voltages and current rich in 5th &

7th harmonics.

LT level have high content of 3rd harmonics.

Critical

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Critical

NR &NER: Sag and Voltage Imbalance,

WR&SR :Harmonics and Sag

ER: Harmonics

Industry Concerns• Apart from harmonics, Industry is also affected due to factors like

interruptions, Flickers Voltage Dips Voltage swell and Unbalance.

• As per Asia Power Quality Initiative Survey Report In September 2015 :

Apart from harmonics, Industry is also affected due to factors like interruptions, Flickers Voltage Dips Voltage swell and Unbalance.

As per Asia Power Quality Initiative Survey Report In September 2015 :

24

Issues and their impactIssues and their impact

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Source of harmonics• Switched mode power supplies

• Dimmers

• Current Regulators

• Frequency Converters

• Voltage source inverters with pulse width modulated converters

• Low power consumption, LEDs lamps

• Electrical arc-furnaces

• Arc welding machines

• Induction motors with irregular magnetizing current associated with saturation of the iron

• All equipment with built-in switching devices or with internal loads with noncharacteristics

• Charging Stations for EVs

Voltage source inverters with pulse width modulated converters

motors with irregular magnetizing current associated with saturation of the iron

in switching devices or with internal loads with non-linear voltage/current

26

Sub synchronous Resonance and low frequency: HVDC converter Sub synchronous Resonance and low frequency: HVDC converter Sub synchronous Resonance and low frequency: HVDC converter Sub synchronous Resonance and low frequency: HVDC converter

SSR frequency filtered from voltage oscillation indicating presence of two

Bus frequency measured from fault recorder indicating 6.69 HZ oscillation.

SSR frequency filtered from voltage oscillation representing

Sub synchronous Resonance and low frequency: HVDC converter Sub synchronous Resonance and low frequency: HVDC converter Sub synchronous Resonance and low frequency: HVDC converter Sub synchronous Resonance and low frequency: HVDC converter

SSR frequency filtered from voltage oscillation indicating presence of two frequencies superimposed on each other.

Bus frequency measured from fault recorder indicating 6.69 HZ oscillation.

SSR frequency filtered from voltage oscillation representing 15.55 Hz and 11.15 Hz respectively.

Inter area oscillations : 0.2 Hz mode

Undamped oscillation observed in the AC tie line on 28th January 2014.

Impact: black out: 1996, 2003- US_canada, 2011 Chile

Inter area oscillations : 0.2 Hz modeSource: POSOCO

Undamped oscillation observed in the AC tie line on 28th January 2014.

Shortcomings in existing standards

• Lack of clarity on measurement of harmonics w.r.t. Issue of Point of Common Coupling

• Lack of clarity on quantum of injection of harmonics by

• Computation of Total demand Distortion(TDD), on demand current or agreed power.

• No monitoring and implementation framework for voltage variation and harmonics• No monitoring and implementation framework for voltage variation and harmonics

• Responsibility of Consumer w.r.t harmonics injection &corrective actions required.

• No provisions for penalty or incentive in the regulations.

• Regulations are silent on other issues of sub–harmonics, inter harmonics, etc. perspective is needed.

• Applicable to only discoms and bulk consumers drawing power at 33 kV& above

Shortcomings in existing standards

Lack of clarity on measurement of harmonics w.r.t. Issue of Point of Common Coupling

Lack of clarity on quantum of injection of harmonics by indiv. consumers

Computation of Total demand Distortion(TDD), on demand current or agreed power.

No monitoring and implementation framework for voltage variation and harmonicsNo monitoring and implementation framework for voltage variation and harmonics

Responsibility of Consumer w.r.t harmonics injection &corrective actions required.

No provisions for penalty or incentive in the regulations.

harmonics, inter harmonics, etc. - so broader

and bulk consumers drawing power at 33 kV& above

29

Proposed changes in connectivity standards

Voltage and Current Harmonics

• Limits of injection of current harmonics by bulk consumers of Common Coupling (PCC), method of harmonic measurement and other matters, IEEE 519-2014 IEEE 519-2014

• Provided that Distribution licensee, to ensure compliance at grid connection points, may make provision in respective supply code made by respective SERC to limit harmonic injection by consumers in its own system.

• For multiple consumers , the allocation of harmonic limits shall be in accordance with the maximum demand recorded during last one year at a PCC..

• The measurement of harmonics shall be done at PCC and not at consumer premises

• At PCC, metering of harmonics will be done to ensure that Voltage harmonics are within prescribed limits on utility side and current harmonics are within prescribed limits for each user.

changes in connectivity standards

consumers and point of harmonic measurement i.e Point of Common Coupling (PCC), method of harmonic measurement and other matters, in accordance with the

30

to ensure compliance at grid connection points, may make provision in respective supply code made by respective SERC to limit harmonic injection by consumers in its own

allocation of harmonic limits shall be in accordance with the maximum

of harmonics shall be done at PCC and not at consumer premises.

At PCC, metering of harmonics will be done to ensure that Voltage harmonics are within prescribed limits on utility side and current harmonics are within prescribed limits for each user.

Harmonics (Proposed)

Voltage and Current Harmonics (contd..)

• Utility shall install Power Quality meters in a phased manner within next three years of publication of this regulation covering at least 33% of the identified measuring points each year

• PCC position shall be decided by utility based on network configuration • PCC position shall be decided by utility based on network configuration mixed user (LV side).

• Measuring and metering of harmonics shall be a continuous process with permanent metersto IEC 61000-4-30 Class A and capable of detecting direction of Harmonics

downstream) and data in regard to harmonics should be available with utility and it is to be shared with consumer. This is to ensure continuous compliance as distortion limits are to be calculated based on daily and weekly percentile values.

meters in a phased manner within next three years of publication of this regulation covering at least 33% of the identified measuring points each year.

PCC position shall be decided by utility based on network configuration i.e dedicated user (HV side) or

31

PCC position shall be decided by utility based on network configuration i.e dedicated user (HV side) or

Measuring and metering of harmonics shall be a continuous process with permanent meters complying capable of detecting direction of Harmonics (whether it is upstream or

regard to harmonics should be available with utility and it is to be shared This is to ensure continuous compliance as distortion limits are to be calculated based

Harmonics (Proposed)

Voltage and Current Harmonics ( contd..)

� In addition to harmonics, periodic measurement of other power quality parameters like

voltage sag, swell and disruptions shall be done on monthly

shared with consumers.shared with consumers.

� In addition to the meters for monitoring of quality

with regard to continuous measurement of quality

consumers having load more than threshold

These consumers shall install meters at their

required by utility.

In addition to harmonics, periodic measurement of other power quality parameters like

voltage sag, swell and disruptions shall be done on monthly basis and reports shall be

32

quality to be installed by utility, the provision

quality parameters shall also be applicable for

limit as decided by appropriate Commission.

their own expenses and share data as and when

Issues before Authority

• Applicable to only discoms and bulk consumers drawing power at 33 kV and above

• Railways has sought relaxation on current harmonics while its voltage harmonics are within CEA prescribed limits.

• IEEE 519 is only a recommendation and

Issues before Authority

and bulk consumers drawing power at 33 kV

sought relaxation on current harmonics while its voltage harmonics are within CEA prescribed limits.

and not a standard.

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Draft distribution network standard ( CEA drafted and sent to ET 45)

• The scope of this standard is to specify main characteristics of voltage at network user’s supply terminal in a distribution system. The characteristic are :• Frequency• Magnitude • Waveform • Symmetry of the line voltages • Waveform • Symmetry of the line voltages ( EN 50160:2010-5 as reference)

• -Definitions includes Low, Medium and High voltages.

• -Values of individual characteristics parameters (flicker severity, voltage dip, swell,

unbalance, Harmonic & inter-harmonin , transient voltages

• -Measurement as per IEC 61000-4-30

• -When notified by BIS, these standards will be adopted

network supply voltage quality

The scope of this standard is to specify main characteristics of voltage at network user’s supply terminal in a distribution system. The characteristic are :

34

Definitions includes Low, Medium and High voltages.

parameters (flicker severity, voltage dip, swell,

, transient voltages etc provided

these standards will be adopted in CEA regulations.

Way forward: Proper implementation

• As measurement and monitoring of harmonics The proposed amendment of CEA regulations would have necessary provisions. provisions.

• Grid codes to put in place a mechanism to check non compliance power quality.

• Consider separately Power quality indices/ KPI while valuating the standards of performance of DISCOMs (

Way forward: Proper implementation

and monitoring of harmonics had been an ignored area. The proposed amendment of CEA regulations would have necessary

to put in place a mechanism to check non compliance of

separately Power quality indices/ KPI while valuating the standards of performance of DISCOMs (SoP).

35

Amendments considering Large scale RE integration

• Large Scale Integration of Renewable with Grid :

• Ambitious target of 175 GW Renewable Capacity by 2022 system operation in regards to Balancing and secure operation of All India Grid.

• During day sufficient conventional capacity may not be available to give adequate reserves.

• Draft national Electricity Plan 2017-22( to be published shortly) indicate that Grid Management during morning and evening RAMP would be a challenge. Management during morning and evening RAMP would be a challenge.

• Renewable generation should not trip under temporary low voltage or high voltage condition due to incident elsewhere in the grid.

• Using Renewable generation as tool for grid security i.e. as asset for system operator rather than liability .

mendments considering Large scale RE integration

Large Scale Integration of Renewable with Grid :

175 GW Renewable Capacity by 2022 will increase challenge of system operation in regards to Balancing and secure operation of All India Grid.

During day sufficient conventional capacity may not be available to give adequate

22( to be published shortly) indicate that Grid Management during morning and evening RAMP would be a challenge. Management during morning and evening RAMP would be a challenge.

Renewable generation should not trip under temporary low voltage or high voltage condition

Using Renewable generation as tool for grid security i.e. as asset for system operator rather

36

Existing Regulations

• Part B of the Existing Regulations deal with Connectivity Standards applicable to the Wind Generating stations and generating standards having inverters.

• B1. Requirement with respect to harmonics, Direct Current ( DC ) injection and Flickersinjection and Flickers

• Major amendments are proposed in :

• B. 2 For generating stations getting connected on or after 6 month form date of publication

Harmonics current Limits

DC Injection

Flicker

Part B of the Existing Regulations deal with Connectivity Standards applicable to the Wind Generating stations and generating standards

B1. Requirement with respect to harmonics, Direct Current ( DC )

Major amendments are proposed in :

B. 2 For generating stations getting connected on or after 6 month

37

IEEE 519

Less than 0.5% of Full load Current

IEC 61000

Proposed Amendments

1.Primary response by Wind & Solar power stations

2. LVRT and HVRT on Renewable Generators

3.Ramp Up & Ramp Down rates specified for RES.

4. Voltage Regulation services for RES.

7.Reactive Power control capability 7.Reactive Power control capability

8.Review of limits of Harmonics

9.Compliance Monitoring

Proposed Amendments

response by Wind & Solar power stations

LVRT and HVRT on Renewable Generators

specified for RES.

38

Frequency Range & Active power control• Existing

• The generating unit shall be capable of operating in the frequency range of 47.5 to 52 Hz and shall be able to deliver rated output in the frequency range of 49.5 Hz to 50.5 Hz.

• Proposed:

• The generating unit shall be capable of operating in the frequency range 47.5 to 52 Hz and shall be able to deliver rated output in the frequency range of 49.5 Hz to 50.5 Hz.be able to deliver rated output in the frequency range of 49.5 Hz to 50.5 Hz.

• Provided that in the frequency range below 49.90 Hz and above 50.05 Hz, or, as prescribed by the Central Commission from time to time, the output shall be as per frequency response requirement mentioned in sub- clause 4 below.

• Operating range of frequencies are consistent

Frequency Range & Active power control

The generating unit shall be capable of operating in the frequency range of 47.5 to 52 Hz and shall be able to deliver rated output in the frequency range of 49.5 Hz to 50.5 Hz.

The generating unit shall be capable of operating in the frequency range 47.5 to 52 Hz and shall be able to deliver rated output in the frequency range of 49.5 Hz to 50.5 Hz.be able to deliver rated output in the frequency range of 49.5 Hz to 50.5 Hz.

that in the frequency range below 49.90 Hz and above 50.05 Hz, or, as prescribed by the Central Commission from time to time, the output shall be as per frequency response

clause 4 below.

range of frequencies are consistent with IEGC regulations.

39

Active power Control and Ramp

• Existing:

• Wind generating station connected at voltage level of 66 kV and above shall have facility to control active power injection in accordance with a set point, which shall be capable of being revised based on direction of the appropriate Load Dispatch Centre.

• Proposed:

• (a). Wind and Solar generating stations with installed capacity of more than 10 MW • (a). Wind and Solar generating stations with installed capacity of more than 10 MW connected at voltage level of 33 66 kV and above shall have facility to control active power injection in accordance with a set point, which shall be capable of being revised based on direction of the appropriate Load Dispatch Centre. the units shall have a droop of 3 to 6% and a dead band

• (b) The operating range of the frequency response and regulation system shall be from 10% to 100% of the maximum AC active power capacity.

• (c). The Wind and Solar generating unit shall be able to control the rate of change of power output at a rate not more than +meteorological conditions. The ramp rate control tolerance shall be


Wind generating station connected at voltage level of 66 kV and above shall have facility to control active power injection in accordance with a set point, which shall be capable of being revised based on direction of the appropriate Load Dispatch Centre.

stations with installed capacity of more than 10 MW stations with installed capacity of more than 10 MW kV and above shall have facility to control active

power injection in accordance with a set point, which shall be capable of being revised based on direction of the appropriate Load Dispatch Centre. Governors of the units shall have a droop of 3 to 6% and a dead band not exceeding + 0.03 Hz.

The operating range of the frequency response and regulation system shall be from 10% to 100% of the maximum AC active power capacity.

The Wind and Solar generating unit shall be able to control the rate of change 10% per minute, independent of

meteorological conditions. The ramp rate control tolerance shall be +10%. 40


• Provisos

• Provided that for large frequency deviation e.g. in excess of 0.3 Hz, the Wind and Solar Generating Station should provide an immediate( within 1 second) real power primary frequency response of at least 10% of the maximum AC active power capacity.

• Provided that wind generating station and inverter based generating stations having capacity 50 MW or more shall have storage capacity of at least 10% of installed capacity as common facility irrespective of generation capacity owned/ developed by different capacity 50 MW or more shall have storage capacity of at least 10% of installed capacity as common facility irrespective of generation capacity owned/ developed by different owners/developers .

• Provided further that if energy storage systems are utilized to comply with the frequency regulation requirements, and during a disturbance, the system frequency falls suddenly and stays below 49.7 Hz, the wind/solar generating station shall provide an immediate frequency response. The time response shall be less than 1 second and should be maintained for at least 10 minutes . After the 10frequency response should not decrease at a ramp rate higher than 10% of the maximum AC active power capacity per minute.


Provided that for large frequency deviation e.g. in excess of 0.3 Hz, the Wind and Solar Generating Station should provide an immediate( within 1 second) real power primary frequency response of at least 10% of the maximum AC active power capacity.

Provided that wind generating station and inverter based generating stations having capacity 50 MW or more shall have storage capacity of at least 10% of installed capacity as common facility irrespective of generation capacity owned/ developed by different capacity 50 MW or more shall have storage capacity of at least 10% of installed capacity as common facility irrespective of generation capacity owned/ developed by different

Provided further that if energy storage systems are utilized to comply with the frequency regulation requirements, and during a disturbance, the system frequency falls suddenly and stays below 49.7 Hz, the wind/solar generating station shall provide an immediate frequency response. The time response shall be less than 1 second and should be

. After the 10th minute, the real power primary frequency response should not decrease at a ramp rate higher than 10% of the maximum

41

Why Active power control and ramp control is required

• With more and more renewable generation capacity,conventional generation stations would be lessconventional units not working.

• If active power support is not available form renewableunder certain situations like sudden outage of units/linesunder certain situations like sudden outage of units/lines

• At present what is required is the ability , it may

• Downside capability is no issue, for upside capabilityoutput or Storage.

• Storage viability is to be seen.

Why Active power control and ramp control is

capacity, during the day , share of power from. Not sufficient inertia in the system due to many

renewable , it would be difficult to manage systemunits/lines.units/lines.

be operationalized based on system requirement.

capability two options operating at say 95% power

42

Voltage RegulationVoltage RegulationVoltage RegulationVoltage RegulationFollowing new clause B2(5) is proposed to be added Regulation in Wind and Solar generating stations

a). Wind Generating stations/ Solar generating continuously-variable, continuously-acting, closed loop control Voltage Regulation System (VRS) i.e. an equivalent to the Automatic Voltage Regulator (AVR) in conventional machines.

b). The VRS set-point shall be adjustable in the range prescribed by the appropriate Commission and it shall also be adjustable by Load Dispatch Center via SCADA.

c). The VRS controller regulation strategy shall be based on proportional plus integral c). The VRS controller regulation strategy shall be based on proportional plus integral (PI) control actions with parallel reactive droop compensation. The VRS Droop shall be adjustable from 0 to 10%.

d). The VRS shall be calibrated such that a change in reactive power will achieve 95% of its final value no later than 1 second following a step change in voltage. The change in reactive power shall not cause excessive voltage excursions or overshoot.

e). The VRS shall be in service as long as the Wind / Solar generating unit is electrically connected to the grid, regardless of MW output including nil generation from the unit.

f). The VRS dead band shall not exceed + 0.1%.

Voltage RegulationVoltage RegulationVoltage RegulationVoltage Regulationis proposed to be added to incorporate feature of Voltage

Regulation in Wind and Solar generating stations:

Solar generating stations ( Solar Parks )shall have a acting, closed loop control Voltage Regulation System

(VRS) i.e. an equivalent to the Automatic Voltage Regulator (AVR) in conventional machines.

point shall be adjustable in the range prescribed by the appropriate Commission and it shall also be adjustable by Load Dispatch Center via SCADA.

The VRS controller regulation strategy shall be based on proportional plus integral The VRS controller regulation strategy shall be based on proportional plus integral (PI) control actions with parallel reactive droop compensation. The VRS Droop shall be

The VRS shall be calibrated such that a change in reactive power will achieve 95% of its final value no later than 1 second following a step change in voltage. The change in reactive power shall not cause excessive voltage excursions or overshoot.

The VRS shall be in service as long as the Wind / Solar generating unit is electrically connected to the grid, regardless of MW output including nil generation from the unit.

0.1%.

43

Compliance Monitoring

The following new Regulation is proposed to be added

It shall be the responsibility of concerned Central/ State Transmission utility to ensure that before connectivity to grid is permitted, all general connectivity conditions stipulated in the CEA Regulations are general connectivity conditions stipulated in the CEA Regulations are complied with. Normally, it shall be in the form of selfthe proforma of connection agreement which can be sample checked/ verified by CTU/STU . Non compliance shall be reported immediately to appropriate commission.

Compliance Monitoring

proposed to be added

shall be the responsibility of concerned Central/ State Transmission utility to ensure that before connectivity to grid is permitted, all general connectivity conditions stipulated in the CEA Regulations are general connectivity conditions stipulated in the CEA Regulations are complied with. Normally, it shall be in the form of self-declaration in

of connection agreement which can be sample checked/ verified by CTU/STU . Non compliance shall be reported immediately to

Thank You Vikram Singh,

Director( Grid Management)

Central Electricity Authority

[email protected], [email protected]

9868898305145

Renewable Energy Integration: Power Quality Issue IV - Power Quality issues... · •Without quality power, electrical device ... Issues and their impact 25. ... •Railways has sought

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