CIRCULAR

AMENDMENTS AND SUPPLEMENTS TO CIRCULAR NO. 25/2016/TT-BCT DATED NOVEMBER 30, 2016 OF MINISTER OF INDUSTRY AND TRADE ON ELECTRICITY TRANSMISSION SYSTEM; CIRCULAR NO. 39/2015/TT-BCT DATED NOVEMBER 18, 2015 OF MINISTER OF INDUSTRY AND TRADE ON ELECTRICITY DISTRIBUTION SYSTEM; CIRCULAR NO. 30/2019/TT-BCT DATED NOVEMBER 18, 2019 ON AMENDMENTS AND SUPPLEMENTS TO SEVERAL ARTICLES OF CIRCULAR NO. 25/2016/TT-BCT DATED NOVEMBER 30, 2016 OF MINISTER OF INDUSTRY AND TRADE ON ELECTRICITY TRANSMISSION SYSTEM, AND CIRCULAR NO. 39/2015/TT-BCT DATED NOVEMBER 18, 2015 OF MINISTER OF INDUSTRY AND TRADE ON ELECTRICITY DISTRIBUTION SYSTEM

Pursuant to the Law on Electricity dated December 3, 2004; the Law on amendments and supplements to certain Articles of the Law on Electricity dated November 20, 2012, and the Law on Amendments and Supplements to several Articles of the Law on Public Investment, the Law on Public-Private Partnership Investment, the Law on Investment, the Law on Housing, the Law on Bidding, the Law on Electricity, the Law on Enterprises, the Law on Special Excise Duties and the Law on Civil Judgment Enforcement, in force as from January 11, 2022;

Pursuant to the Government's Decree No. 96/2022/ND-CP dated November 29, 2022, defining the functions, tasks, powers and organizational structure of the Ministry of Industry and Trade;

Pursuant to the Government’s Decree No. 137/2013/ND-CP dated October 21, 2013 elaborating on the implementation of certain articles of the Law on Electricity and the Law on Amendments and Supplements to certain Articles of the Law on Electricity;

Upon the request of the Director of the Electricity Regulatory Authority;

The Minister of Industry and Trade herein promulgates the Circular on amendments and supplements to the Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade on electricity transmission system; the Circular No. 39/2015/TT-BCT dated November 18, 2015 of the Minister of Industry and Trade on electricity distribution system; the Circular No. 30/2019/TT-BCT dated November 18, 2019 on amendments and supplements to several Articles of the Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade on electricity transmission system, and the Circular No. 39/2015/TT-BCT dated November 18, 2015 of the Minister of Industry and Trade on electricity distribution system.

Article 1. Amendments and supplements to several Articles of the Circular No. 30/2019/TT-BCT dated November 18, 2019 on amendments and supplements to several Articles of the Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade on electricity transmission system, and the Circular No. 39/2015/TT-BCT dated November 18, 2015 of the Minister of Industry and Trade on electricity distribution system

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 “7. Amending and supplementing clause 1 of Article 31 as follows:

1. The customer having access to the transmission grid shall be responsible for investing in, installing and managing operation of the information system under their delegated authority, and ensuring it is connected to the information system under the control of the power transmission unit and the Dispatch Division given control (hereinafter referred to as authorized Dispatch Division); ensuring that data (including those of SCADA, PMU and fault recorder) are communicated and transmitted in a full, reliable and continuous manner for the purposes of normal operation of the electrical power system and market. The indispensable means of communication serving dispatching and operation activities in an electricity transmission system shall include direct communication channel, telephone, DIM and computer network.”.

2. Amending clause 10 of Article 1 as follows:

 “10. Amending clause 2 of Article 37 as follows:

2. Connection requirements of the Control Center

a) Requirements for connection to the communications system

- Get a data transmission line connected to a communication system of the authorized Dispatch Division.   Where there are multiple authorized Dispatch Divisions, all of them shall be responsible for agreeing on the data-sharing method;

- Connect two data transmission lines (including an active line and a standby line) to the control and information system of the power plant or station remotely controlled by the Control Center;

- The indispensable means of communication intended for dispatch between the authorized Dispatch Divisions and the Control Center shall comprise direct communication channel, telephone, DIM and computer network. The indispensable means of communication between the Control Center and power plants or stations shall comprise direct communication channel, telephone, and computer network.

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- Make a connection to the SCADA system of the authorized Dispatch Division.   Where there are multiple authorized Dispatch Divisions, all of them shall be responsible for sharing data;

- Make two connections to such terminal device as RTU or Gateway, the control system of the power plant or station, and to the switchgear on the electrical grid remotely controlled by the Control Center.

c) The Control Center must install monitoring screens connected to closed-circuit television cameras at power plants or stations.”.

3. Amending clause 11 of Article 1 as follows:

 “11. Amending clause 3 of Article 38 as follows:

3. The generating set at a power plant must be capable of playing its role in controlling the primary frequency which falls outside of the dead band of the governor; of meeting at least 50% of its primary frequency control capacity within the first 15 seconds, and 100% of that within 30 seconds, as well as maintaining such level of capacity for at least 15 following seconds.   The primary frequency control capacity of a generating set shall be calculated according to the actual frequency deviation, its remaining available capacity, the primary response limit varying depending on its technology, and the installed parameters required by the Power System and Market Operator.".    

4. Amending clause 12 of Article 1 as follows:

 “12. Amending Article 42 as follows:

Article 42. Technical requirements of wind and solar power plants

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a) Free generation mode: Generating the highest possible power shall depend on transformation of the primary energy source (e.g. wind or solar energy);

b) Generation capacity control mode:

Wind and solar power plants must be capable of restricting the generation capacity according to a dispatch instruction in the following cases:

- If the primary energy source varies to the degree lower than the limit according to the dispatch instruction, generating the highest possible power shall be required;

- If the primary energy source varies to the degree equal to or greater than the limit according to the dispatch instruction, generating the power equaling the limit according to the dispatch instruction with the tolerance falling within the ± 01% band of the rated capacity shall be required.

2. Wind and solar power plants which are, at any time, getting connected to electrical grids must have capacity to maintain generation of power for a minimum period of time corresponding to the respective power-generating frequency band shown in Table 8 below:

Table 8

Required minimum time length for maintenance of power generation at a wind or solar power plant corresponding to the respective frequency band of the power system

Frequency band

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From 47.5 Hz to 48.0 Hz

10 minutes

From greater than 48 Hz to less than 49 Hz

30 minutes

From 49 Hz to 51 Hz

Continuous generation

From greater than 51 Hz to 51.5 Hz

30 minutes

From greater than 51,5 Hz to 52 Hz

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3. When the power system’s frequency is greater than 50.5 Hz, wind and solar power plants may reduce active power according to the comparative slope of the droop characteristics line within the steep gradient range of between 2% and 10%. The set value of the comparative slope of the droop characteristics line is calculated and determined by the authorized Dispatch Division. The process of reduction in active power shall be recorded from the start no later than 02 seconds after recording the frequency of more than 50.5 Hz and shall be completed within 15 seconds. 

4. Wind and solar power plants must be capable of adjusting reactive power according to characteristics shown in the following diagram and described in point a and b of this clause:

a) If a power plant produces active power greater than or equal to 20% of the rated active power, and voltage at the high voltage side of the step-up transformer at the power plant within the nominal band of ± 10%, it shall be capable of adjusting reactive power continuously within the power factor range from 0.95 (in the reactive power producing mode) to 0.95 (in the reactive power receiving mode) on the high voltage side of the step-up transformer at the power plant, or at the point of separating measurement of the reactive power of each plant when there are many plants all connected to a step-up transformer corresponding to the rated capacity;

b) If a power plant generates the active power less than 20% of the rated power, it may reduce ability to receive or generate the reactive power, depending on its characteristics.

5. Voltage and reactive power control mode:

a) Wind and solar power plants must be capable of controlling voltage and reactive power:

- in the voltage control mode used according to the set voltage value or the voltage-adjusting droop characteristics (the characteristics of the relation between voltage and reactive power);

- in the control mode used according to the set value of reactive power;

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b) If voltage at the high voltage side of the step-up transformer at a power plant falls within the band of ± 10 % of the nominal voltage, wind or solar power plants must be capable of adjusting voltage at the low pressure side of the step-up transformer with the deviation no more than ± 0,5 % of the rated voltage (compared to the set voltage value) whenever the reactive power produced by a generating set remains within the permissible working band, and completing such adjustment within 05 seconds.

6. A wind and solar power plant which is, at any time, obtaining grid connection must be capable of maintaining its power generation corresponding to the respective voltage band at the high voltage side of its step-up transformer within the following time frames:

a) If voltage is less than 0.3 pu, the minimum maintenance time will be 0.15 second;

b) If voltage ranges from 0.3 pu to under 0.9 pu, the minimum maintenance time shall be calculated according to the following formula:

T_min = 4 x U – 0.6

Where:

- T_min (second): Minimum time required for maintenance of power generation;

- U (pu): Actual voltage at the high voltage side of the plant’s step-up transformer expressed in pu (per-unit);

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d) If voltage ranges from 1.1 pu to under 1.15 pu, the wind and solar power plant must maintain the power generation within 03 seconds;

dd) If voltage ranges from 1.15 pu to under 1.2 pu, the wind and solar power plant must maintain power generation within 0.5 second.

7. The level of phase imbalance, total harmonic distortion and voltage flicker caused by wind or solar power plants at the high voltage side of its step-up transformer shall not be allowed to exceed any of the values specified in Article 7, 8 and 9 herein.

8. A wind or solar power plant must invest in controlling and automatic equipment and systems to ensure stable, reliable and secure connection to the Automatic Generation Control (AGC) of the Electricity System and Market Operator to enable the remote control of its power generation capacity according to the dispatch instruction received from the Electricity System and Market Operator.

9. A wind or solar power plant shall maintain its grid connection when the frequency fluctuation rate in the power system which is measured within the time frame of 500 milliseconds falls within the range from 0 Hz/second to 01 Hz/second.

10. When voltage at the high voltage side of the step-up transformer of a power plant falls outside the band of ± 10 % of the rated voltage, the power plant must be capable of setting the priority mode of generation of reactive current (when the voltage is low), or absorption of reactive current (when voltage is high) to sustain the power system during breakdown, in which case the reactive current can vary from 0% to 10% of the power plant's rated current for every 1 % voltage change with the permissible maximum tolerance of 20 % (the rate of change is determined by the authorized Dispatch Division), and response time is not later than 100 milliseconds.

11. After such breakdown is successfully handled and the power system returns to the normal operating mode, a power plant must ensure:

a) it is capable of restoring the active power to return to the operating mode existing before the breakdown occurs with the rate of increase in the active power not less than 30% of the rated capacity per second, and not more than 200% of the rated power per second;

b) When sets of wind turbines or inverters of a solar power plant are shut down in case of the power system breakdown that lasts longer than the minimum required time of grid connection, these sets shall be reconnected to the power system not earlier than 03 minutes after the power system returns to normal operation at the rate of recovery of active power which is not greater than 10% of the rated power per minute.

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5. Amending clause 17 of Article 1 as follows:

 “17. Amending Article 73 as follows:

Article 73. Technical requirements of ancillary services

1. Secondary frequency control: The generating set or power plant providing the secondary frequency control service must be capable of starting to provide frequency control power within 20 seconds after receiving AGC signals from the Power System and Market Operator; completely providing the registered secondary frequency control power within 10 minutes, and maintaining this power level within at least 15 minutes.

2. Quick start: The generating set or power plant providing quick-start reserve must be capable of increasing to the rated power within 25 minutes and maintaining it for a minimum of 08 hours.

3. Voltage adjustment: The generating set or power plant providing the voltage adjustment service must be capable of changing the reactive power outside the adjustment band prescribed in clause 2 of Article 38 and clause 4 of Article 42 herein, meeting the requirements imposed by the Power System and Market Operator.

4. Must-run operation reserves for power system security purposes: The generating set or power plant providing the must-run operation service for electricity system security purposes must be capable of increasing to the rated power within 1 hour and maintaining such rated power for a minimum of 8 hours (excluding the start time).

5. Black start: The generating set or power plant providing the black start service must be capable of automatic cold start without needing any power supply from the national electricity system; connecting and supplying power to the power system after successful start.”.

6. Amending clause 18 of Article 1 as follows:

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Article 74: Determination of demands and provision of ancillary services

1. General rules for determining demands for ancillary services, including:

a) Maintain the electrical power and capacity reserve level of the power system in order to meet power system operation and security standards;

b) Incur minimum expenses according to conditions and binding arrangements in the national electricity system.

2. The Power System and Market Operator, and the Vietnam Electricity Corporation shall be responsible for calculating demands for ancillary services for the national electricity system and seeking approval from the Vietnam Electricity Corporation according to the Procedures for determination of demands and provision of ancillary services issued by the Electricity Regulatory Authority.”.

7. Amending clause 10 of Article 2 as follows:

 “10. Amending clause 1 and 2 of Article 38 as follows:

1. The power plant connected to the distribution grid with the generation capacity of at least 10 MW (irrespective of any connection voltage level) and transformer substations of 110 kV not yet connected to the Control Center are required to be equipped with a Gateway or RTU, and establish two connections physically independent of the SCADA system of the authorized Dispatch Division. If power plants or transformer substations are under the control of multiple authorized Dispatch Divisions, these Dispatch Divisions shall be responsible for sharing information necessary for coordination in operation of the power system.

2. If the power plant connected to the distribution grid with the generation capacity of at least 10 MW has already connected to the Control Center, it must be equipped with a Gateway or RTU having one connection to the SCADA system of the authorized Dispatch Division, and two connections to the control system at the Control Center. Transformers of 110 kV that are controlled and operated remotely by the Control Center are required to be furnished with a Gateway or RTU making two connections to the control system at the Control Center and sharing information from the Control Center to the authorized Dispatch Division.”.

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 “11. Amending and supplementing Article 40 as follows:

Article 40. Requirements of wind power plants and solar power plants with greater than 1MW generation capacity connected to the distribution grid at the medium-voltage or higher level

1. Wind and solar power plants must be capable of maintaining generation of active power in the following modes:

a) Free generation mode: Generating the highest possible power may depend on transformation of the primary energy source (e.g. wind or solar energy);

b) Generation capacity control mode:

Wind and solar power plants must be capable of restricting the generation capacity according to a dispatch instruction in the following cases:

- If the primary energy source varies to the degree lower than the limit according to the dispatch instruction, generation of the highest possible power shall be required;

- If the primary energy source varies to the degree equal to or greater than the limit according to the dispatch instruction, generating the power equaling the limit according to the dispatch instruction with the tolerance falling within the ± 01% band of the rated capacity shall be required.

2. Wind and solar power plants which are, at any time, getting connected to electrical grids must have capacity to maintain generation of power for a minimum period of time corresponding to the respective power-generating frequency band shown in Table 5b below:

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Required minimum time length for maintenance of power generation of a wind or solar power plant corresponding to the respective frequency band of the power system

Frequency band

Required minimum time length

From 47.5 Hz to 48.0 Hz

10 minutes

From greater than 48 Hz to less than 49 Hz

30 minutes

From 49 Hz to 51 Hz

Continuous generation

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30 minutes

From greater than 51,5 Hz to 52 Hz

01 minute

3. When the power system’s frequency is greater than 50.5 Hz, a wind and solar power plant may reduce active power according to the comparative slope of the droop characteristics line within the steep gradient range of between 02% and 10%. The set value of the comparative slope of the droop characteristics line is calculated and determined by the authorized Dispatch Division. The process of reduction in active power shall be recorded from the start no later than 02 seconds after recording the frequency of more than 50.5 Hz and shall be completed within 15 seconds. 

4. A wind or solar power plant must be capable of adjusting reactive power according to the characteristics shown in the following diagram and described in point a and b of this clause:

a) If the power plant produces the active power greater than or equal to 20% of the rated active power, and voltage on the high voltage side of its step-up transformer falling within the nominal band of ± 10%, it shall be capable of adjusting reactive power continuously within the power factor range from 0.95 (in the reactive power producing mode) to 0.95 (in the reactive power receiving mode) at the high voltage side of the step-up transformer at the power plant, or at the point of separating measurement of the reactive power of each plant when there are many plants all connected to a step-up transformer corresponding to the rated capacity;

b) If the power plant generates the active power less than 20% of the rated power, it may reduce its capability to receive or generate the reactive power, depending on its characteristics.

5. Voltage and reactive power control mode:

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- in the voltage control mode used according to the set voltage value or the voltage-adjusting droop characteristics (the characteristics of the relation between voltage and reactive power);

- in the control mode used according to the set value of reactive power;

- in the control mode used according to power factors;

b) If voltage at the high pressure side of the step-up transformer at a power plant falls within the band of ± 10 % of the nominal voltage, wind or solar power plants must be capable of adjusting voltage at the low pressure side of the step-up transformer with the deviation no more than ± 0,5 % of the rated voltage (compared to the set voltage value) whenever the reactive power produced by a generating set remains within the permissible working band, and completing such adjustment within 05 seconds.

6. A wind and solar power plant which is, at any time, obtaining grid connection must be capable of maintaining its power generation corresponding to the voltage band at the high pressure side of its step-up transformer within the following time frames:

a) If voltage is less than 0.3 pu, the minimum maintenance time will be 0.15 second;

b) If voltage ranges from 0.3 pu to under 0.9 pu, the minimum maintenance time shall be calculated according to the following formula:

T_min = 4 x U – 0.6

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- T_min (second): Minimum time required for maintenance of power generation;

- U (pu): Actual voltage at the high pressure side of the plant’s step-up transformer expressed in pu (per-unit);

c) If voltage ranges from 0.9 pu to under 1.1 pu, the wind and solar power plant shall be required to maintain continuous power generation;

d) If voltage ranges from 1.1 pu to under 1.15 pu, the wind and solar power plant must maintain the power generation within 03 seconds;

dd) If voltage ranges from 1.15 pu to under 1.2 pu, the wind and solar power plant must maintain power generation within 0.5 second.

7. The level of phase imbalance, total harmonic distortion and voltage flicker caused by wind or solar power plants at the high pressure side of its step-up transformer shall not be allowed to exceed any of the values specified in Article 6, 7 and 8 herein.

8. A wind or solar power plants must invest in its controlling and automatic equipment and systems to ensure stable, reliable and secure connections to the Automatic Generation Control (AGC) of an authorized Dispatch Division to enable the remote control of its power generation capacity according to the dispatch instruction received from the authorized Dispatch Division.

9. A wind or solar power plant shall maintain its grid connection when the frequency fluctuation rate in the power system which is measured within the time frame of 500 milliseconds falls within the range from 0 Hz/second to 01 Hz/second.

10. When voltage at the high voltage side of the step-up transformer of a power plant falls outside the band of ± 10 % of the rated voltage, the power plant must be capable of prioritizing generation of reactive current (when the voltage is low), or absorption of reactive current (when voltage is high) to sustain the power system during breakdown, in which case the reactive current can vary from 0% to 10% of the power plant's rated current for every 1 % voltage change with the permissible maximum tolerance of 20 % (the rate of change is determined by the authorized Dispatch Division), and response time is not later than 100 milliseconds.

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a) it is capable of restoring the active power to return to the operating mode existing before the breakdown occurs with the rate of increase in the active power not less than 30% of the rated capacity per second, and not more than 200% of the rated power per second;

b) When sets of wind turbines or inverters of a solar power plant are shut down in case of the power system breakdown that lasts longer than the minimum required time of grid connection, these sets shall be reconnected to the power system not earlier than 03 minutes after the power system returns to normal operation at the rate of recovery of active power which is not greater than 10% of the rated power per minute.

12. A power plant is required to maintain grid connection when the voltage at the high voltage side of its step-up transformer happens to make an instantaneous phase swing of up to 20 degrees within 100 milliseconds without causing any power generation interruption or reduction.”.

9. Amending clause 13 of Article 2 as follows:

 “13. Amending clause 2 of Article 42 as follows:

2. Connection requirements of the Control Center

a) Requirements for connection to communications systems:

- Get a data transmission line connected to a communication system of the authorized Dispatch Division.   Where there are multiple authorized Dispatch Divisions, all of them shall be responsible for agreeing on the data-sharing method;

- Connect two data transmission lines (including an active line and a standby line) to the control and information system of the power plant or station remotely controlled by the Control Center;

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b) Requirements for connection to the SCADA system:

- Make a connection to the SCADA system of the authorized Dispatch Division.   Where there are multiple authorized Dispatch Divisions, all of them shall be responsible for sharing data;

- Make two connections to such terminal device as RTU or Gateway, the control system of the power plant or station, and to the switchgear on the electrical grid remotely controlled by the Control Center.

c) The Control Center must install monitoring screens connected to closed-circuit television cameras at the power plant or station.”.

Article 2. Amendments and supplements to several Articles of the Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade on the electricity transmission system

1. Amending and supplementing clause 16 of Article 3 as follows:

 “16. Power transmission unit refers to an electricity entity that obtains the license for transmission of electricity.”.

2. Adding point d to clause 1 of Article 37 as follows:

 “d) Total rated capacity of power plants under the Control Center shall not exceed the rated capacity of the largest generating set in operation in the national power system as determined by the Power System and Market Operator.”.

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 “1. The wind or solar power plant having the installed capacity of greater than 30MW shall be required to invest in the control and automatic equipment and system to ensure stable, reliable and secure connection to Automatic Generation Control (AGC) of the Power System and Market Operator for the remote control of generation of the generating set according to the dispatch instruction received from the Power System and Market Operator. For power plants within an industrial zone that only sell part of their generated power to the national power system, the necessity of furnishing an AGC system is agreed upon and clearly stated in a Connection Agreement by the parties. Specific technical requirements concerning connection of the AGC signal of the generating set to SCADA/EMS of the Power System and Market Operator are specified in the Regulations on technical and operational requirements of SCADA brought into force by the Electricity Regulatory Authority.”.

4. Supplementing clause 8 of Article 38 as follows:

 “8. The generating set of a power plant shall maintain its grid connection when the frequency fluctuation rate in the power system which is measured within the time frame of 500 milliseconds falls within the range from 0 Hz/second to 01 Hz/second.”.

5. The title of Article 46 shall be revised as follows:

 “Article 46. Provision of documentation required for checking whether power is on at connection points for test run and acceptance testing purposes”.

6. Amending and supplementing the first hyphen bullet of point c of clause 1 of Article 46 as follows:

 “- Technical specifications of installed equipment include technical specifications of connected lines;”.

7. The title of Article 47 shall be revised as follows:

 “Article 47. Checking whether power is on at connection points for test run and acceptance testing purposes”.

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 “2. Power transmission unit shall be responsible for agreeing with the customers who wish to get connected on the process of checking the submitted documents, the report of acceptance test and the actual status of installation of equipment as per the Connection Agreement.”.

9. The title of Article 48 shall be revised as follows:

 “Article 48. Power-on status at connection points for test run and acceptance testing purposes”.

10. Amending and supplementing point a of clause 1 of Article 48 as follows:

 “a) Legal and technical dossier of a construction project:

- Written confirmation and commitment of the customer wishing to obtain power connection, stating that equipment within the power-on range has been tested and checked to meet the operational and technical requirements agreed at the connection points and fully comply with the law;

- Copy of the Report of inspection of power-on status at the connection points, stating that it has fully met the requirements set forth in the Connection Agreement;

- The metering system that has been completed in accordance with regulations, and in which indicators of delivery and receipt of electricity shown by meters installed have been cut off;

- The Power Purchase Agreement signed, or the agreement on sale and purchase, or delivery and receipt, of power;”.

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 “5. The electric grid, power plant and electrical equipment after the connection point of the customer that wishes to obtain connection may be officially put into operation only after having a full report of the partial and complete test, fully meeting the requirements specified in this Circular, regulations on planning, land, construction, fire prevention and fighting, environment and other relevant legal regulations.”.

12. The title of Article 52 shall be revised as follows:

 “Article 52. Provision of documentation required for checking whether power is on at points of connection of equipment of power transmission units for test run or acceptance testing purposes”.

13. Amending point dd of clause 1 of Article 52 as follows:

 “dd) The diagram showing the details of the plan of connection of the power facility of the power transmission unit and the parameters of the connection line;”.

14. The title of Article 53 shall be revised as follows:

 “Article 53. Power-on status at points of connection of equipment of power transmission units for test run or acceptance testing purposes”.

15. Amending and supplementing point a of clause 1 of Article 53 as follows:

 “a) Legal and technical dossier:

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- The metering system that has been completed in accordance with regulations, and in which indicators of delivery and receipt of electricity shown by meters installed have been cut off;”.

16. Amending and supplementing clause 4 of Article 59 as follows:

 “4. The transmission power system operates in the extreme emergency mode when one of the following conditions occurs or exists:

a) The frequency of the power system falls outside of the allowable frequency range in case of a single incident happening in the power system as specified in Article 4 hereof, or the frequency of the power system continues to decrease to below 49.5Hz after all backup sources have been mobilized;

b) The load-carrying rate of any equipment within the transmission grid or any equipment connected to the transmission grid shall be at least 110% of the rated value when failure of such equipment occurring due to overload may lead to the disintegration of the power system;

c) The voltage at any node on the transmission grid is low, resulting in the relay shedding the load according to the working low voltage; the voltage in the transmission grid is lower than 10% of the rated voltage, or there is a risk of collapse of the voltage in the power system as calculated by the Dispatch Division when there are no adjustment measure other than shedding of the load and the voltage continues to be in a downward trend.”.

17. Supplementing point dd of clause 3 of Article 60 as follows:

 “dd) Impose the configuration requirement for mobilization of the least available sources and inertia in the power system to ensure safe operation of the power system.”.

18. Amending and supplementing clause 3 of Article 62 as follows:

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19. Amending and supplementing point a and c of clause 3 of Article 64 as follows:

 “a) Change the generating capacity of the generating set; stop or start the generating set to restore the power system to the normal operating mode;

c) The automatic load shedding system must be arranged and installed properly to ensure that the power system does not disintegrate in case of failure or breakdown. The Power System and Market Operator shall be responsible for determining the installation location and setting values ​​of the protective relays in order to shed the load in the event of failure or breakdown occurring in the power system to ensure safety and security of the power system;”.

Article 3. Amendments and supplements to several Articles of the Circular No. 39/2015/TT-BCT dated November 18, 2015 of the Minister of Industry and Trade on electricity distribution system

1. Amending and supplementing clause 1 of Article 37 as follows:

 “1. The power plant connected to the distribution grid with the capacity of at least 10 MW or the transformer substation of 110 kV shall be furnished with the information system which is connected compatibly with the information system of the authorized Dispatch Division to serve the purposes of communication and data transmission necessary for operation of the power system. The indispensable means of communication intended for dispatch shall comprise direct communication channel, telephone, and computer network.”.

2. Adding point e of clause 2 of Article 39 as follows:

 “e. Generating sets of power plants shall maintain its grid connection when the frequency fluctuation rate in the power system which is measured within the time frame of 500 milliseconds falls within the range from 0 Hz/second to 01 Hz/second.

3. Adding Article 40a underneath Article 40 as follows:

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1. Sources of wind and solar power which are, at any time, getting connected to the electric grid shall be required to have capacity to maintain generation of power for a minimum period of time corresponding to the respective power-generating frequency band shown in Table 5c below:

Table 5c.

Minimum time of maintenance of generation in proportion to frequency bands of power systems

Frequency band

Required minimum time length

From 48 Hz to less than 49 Hz

30 minutes

From 49 Hz to 51 Hz

Continuous generation

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30 minutes

2. If the frequency of power system is greater than 50.5 Hz, the active power generated by the source of solar or wind power shall be reduced according to the following formula:

Where:

- ΔP: Reduced amount of active power (MW);

- P_m: Active power determined at the time prior to power reduction (MW);

- f_n: Frequency of the power system prior to power reduction (Hz).

3. Sources of solar or wind power shall be capable of maintaining continuous generation of power within the voltage bands at connection points as prescribed in Table 5d hereunder:

Table 5d.

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Voltage at connection points

Required minimum time length

Less than 50% of the nominal voltage

Not required

From 50% to less than 85% of the nominal voltage

02 seconds

From 85% to 110% of the nominal voltage

Continuous generation

From greater than 110% to 120% of the nominal voltage

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Greater than 120% of the nominal voltage

Not required

4. The source of solar or wind power shall not cause any invasion of direct current into the power distribution grid to the extent that such current exceeds 0.5% of the rated current at a connection point.

5. Sources of solar or wind power shall conform to regulations on voltage, phase balance, harmonics, voltage flicker and earthing mode prescribed in Article 5, 6, 7, 8 and 10 herein.

6. Sources of solar or wind power shall be equipped with security devices meeting the following requirements:

a) Automatically disconnect the power distribution grid in case of failure or breakdown occurring inside the source of solar or wind power;

b) Automatically disconnect the power distribution grid in case of loss of power supplied from the power distribution grid and fail to produce power to be supplied to the power distribution grid in case of loss of electricity currently taking place in the power distribution grid;

c) Do not automatically reconnect the electric grid when the following requirements have not been satisfied yet:

- The power grid’s frequency is maintained within the band from 48Hz to 51Hz during the minimum period of 60 seconds;

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d) Customers demanding connection shall negotiate and agree on the requirements regarding security systems with power distribution units, inter alia including at least protections specified in point a, b and c of this clause, over-voltage, low-voltage and frequency protection.  

7. In addition to the requirements specified in clause 1 through 6 of this Article, sources of solar or wind power with capacity of between 100 kW and 1 MW connected to the medium-voltage grid must satisfy the following technical requirements:

a) Ensure that the reactive power control mode is activated according to the power factor control mode with the power factor value (cosphi) set at the request of the authorized Dispatch Division, unless otherwise agreed upon with the authorized Dispatch Division;

b) Have the capacity to set the priority mode of generation of active or reactive power at the request of the authorized Dispatch Division when voltage at connection points falls outside the band of continuous operation requirements specified in clause 3 of this Article.

8. Investors in sources of solar and wind power connected to the medium-voltage grid with the capacity of between 100 kW and 1 MW shall be responsible for negotiating and reaching agreement with the power distribution unit on equipment and means of connection with the collection, monitoring and control system of the distribution Dispatch Division.”

4. Adding point d to clause 1 of Article 42 as follows:

 “d) Total rated capacity of power plants under the Control Center shall not exceed the rated capacity of the largest generating set in operation in the national power system as determined by the Power System and Market Operator.”.

5. The title of Article 47 shall be revised as follows:

 “Article 47. Requirements concerning provision of the dossier for checking whether power is on at connection points for test run or acceptance test purposes to be imposed upon customers having access to the power distribution grid connected to the power system at a voltage of 110 kV and customers whose generating sets are connected to the power system at the medium voltage".     

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 “Article 48. Requirements concerning provision of the dossier for checking whether power is on at connection points for test run or acceptance test purposes to be imposed upon customers whose stations of their own are connected to the medium-voltage grid”.    

7. The title of Article 49 shall be revised as follows:

 “Article 49. Checking whether power is on at connection points for test run and acceptance testing purposes”.

8. Amending and supplementing clause 3 of Article 49 as follows:

 “3. Power distribution units shall be responsible for agreeing with the customers who demand power connection on the process of checking the submitted documents, the report of acceptance test and the actual status of installation of equipment as per the Connection Agreement.”.

9. The title of Article 50 shall be revised as follows:

 “Article 50. Power-on status at connection points for test run and acceptance testing purposes”.

10. Amending and supplementing point a of clause 1 of Article 50 as follows:

 “a) Legal and technical dossier:

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- Copy of the Report of inspection of power-on status at the connection points, stating that it has fully met the requirements set forth in the Connection Agreement;

- The metering system that has been completed and on which indicators of electricity delivery and receipt have been cut off;

- The Power Purchase Agreement signed, or the agreement on sale and purchase, or delivery and receipt, of power;”.

11. Supplementing clause 4 of Article 50 as follows:

 “4. For the customers using electricity connected to the medium-voltage grid, it is allowed to turn on power at the connection points immediately after having the report of inspection of the power-on status at connection points, stating that they comply with the requirements set forth in the Connection Agreement, fully meet legal, technical, dispatching and operational requirements specified in clause 1 of this Article, and electrical safety requirements.”.

12. Amending and supplementing point d of clause 1 of Article 51 as follows:

 “d) The electric grid, power plant and electrical equipment after connection points of the customer that wishes to obtain connection may be officially put into operation only after having a full report of the partial and complete test, fully meeting the requirements specified in this Circular, regulations on planning, land, construction, fire prevention and fighting, environment and other relevant legal regulations.”.

13. The title of Article 55 shall be revised as follows:

 “Article 55. Provision of documentation required for checking whether power is on at points of connection to equipment of power distribution units for test run or acceptance testing purposes”.

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 “Article 56. Power-on status at points of connection of equipment of power distribution units for test run or acceptance testing purposes”.

15. Amending and supplementing point a of clause 1 of Article 56 as follows:

 “a) Legal and technical dossier:

- Written confirmation and commitment of the Investor stating that equipment within the power-on range has been tested and checked to meet the operational and technical requirements agreed at the connection points, and fully comply with the law;

- The metering system that has been completed and on which indicators of electricity delivery and receipt have been cut off;”.

16. Amending and supplementing clause 1 of Article 62 as follows:

 “1. Manage and operate electric equipment and grids falling within their remit to ensure that they meet operational and technical requirements set out in this Circular, and comply with regulations regarding Dispatch Procedures, Operating Procedures, Troubleshooting/Failure or Breakdown Response Procedures in the national power system adopted by the Ministry of Industry and Trade, and other relevant legal regulations.”.

17. Amending and supplementing point a of clause 1 of Article 64 as follows:

 “a) Manage and operate electric equipment and grids falling within their remit to ensure that they meet operational and technical requirements set out in this Circular, and comply with regulations regarding Dispatch Procedures, Operating Procedures, Troubleshooting/Failure or Breakdown Response Procedures in the national power system adopted by the Ministry of Industry and Trade, and other relevant legal regulations.”.

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"2a. Departments of Industry and Trade of provinces and centrally-run cities shall be responsible for inspecting and supervising the compliance with the provisions of this Circular within their range of authority.”.

Article 4. Implementation provisions

1. This Circular is entering into force as of February 16, 2023.

2. Rescinding several articles and clauses of the Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade on electricity transmission system, and the Circular No. 39/2015/TT-BCT dated November 18, 2015 of Minister of Industry and Trade on electricity distribution system, as follows:

a) Deleting the second hyphen of point a of clause 3 of Article 92 and clause 2 of Article 94 of the Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade on electricity transmission system;

b) Deleting Article 92, 93, 94, 95, 96, 97 and 98 in the Circular No. 39/2015/TT-BCT dated November 18, 2015 of Minister of Industry and Trade on electricity distribution system.

3. Where electrical equipment has been put into operation, or there is a contract for procurement and installation of equipment in force before the effective date of this Circular that prescribes technical requirements and specifications different from those specified in this Circular, relevant regulations in force before the effective date of this Circular shall govern.

4. In the course of implementation of this Circular, if there is any difficulty that may arise, entities concerned shall send feedback to the Electricity Regulatory Authority to seek its decision or action within its jurisdiction, or for its reporting to the Ministry of Industry and Trade to seek its solution./.

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PP. MINISTER
DEPUTY MINISTER




Dang Hoang An

Thông tư 39/2022/TT-BCT sửa đổi Thông tư 25/2016/TT-BCT quy định hệ thống điện truyền tải, Thông tư 39/2015/TT-BCT quy định hệ thống điện phân phối và Thông tư 30/2019/TT-BCT sửa đổi Thông tư 25/2016/TT-BCT quy định hệ thống điện truyền tải và Thông tư 39/2015/TT-BCT quy định hệ thống điện phân phối do Bộ trưởng Bộ Công thương ban hành