Circular 39/2022/TT-BCT amend Circular 25/2016/TT-BCT, Circular 39/2015/TT-BCT and Circular 30/2019/TT-BCT

CIRCULAR

Amending and supplementing a number of articles of Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade on regulations on electricity transmission system, Circular No. 39/2015/TT-BCT dated November 18, 2015 of the Minister of Industry and Trade on regulations on electricity distribution system and Circular No. 30/2019/TT-BCT dated November 18, 2019 amending and supplementing a number of articles of the Minister of Industry and Trade’s Circular No. 25/2016/TT-BCT dated November 30, 2016 on regulations on electricity transmission system and Circular No. 39/2015/TT-BCT dated November 18, 2015 on regulations on electricity distribution system

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Pursuant to the Electricity Law dated December 03, 2004; the Law Amending and Supplementing a Number of Articles of the Electricity Law dated November 20, 2012; and the Law on Amending and Supplementing a Number of Articles of the Law on Public Investment, Law on Investment in the Form of Public-Private Partnership, Law on Investment, Housing Law, Bidding Law, Electricity Law, Law on Enterprises, Law on Excise Tax, and Law on Enforcement of Civil Judgments dated 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, detailing a number of articles of the Electricity Law and the Law Amending and Supplementing a Number of Articles of the Electricity Law;

At the proposal of the Director of Electricity Regulatory Authority of Vietnam;

The Minister of Industry and Trade promulgates the Circular amending and supplementing a number of articles of Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade on regulations on electricity transmission system, Circular No. 39/2015/TT-BCT dated November 18, 2015 of the Minister of Industry and Trade on regulations on electricity distribution system and Circular No. 30/2019/TT-BCT dated November 18, 2019 amending and supplementing a number of articles of the Minister of Industry and Trade’s Circular No. 25/2016/TT-BCT dated November 30, 2016 on regulations on electricity transmission system and Circular No. 39/2015/TT-BCT dated November 18, 2015 on regulations on electricity distribution system.

Article 1. Amending and supplementing a number of articles of Circular No. 30/2019/TT-BCT dated November 18, 2019 amending and supplementing a number of articles of the Minister of Industry and Trade’s Circular No. 25/2016/TT-BCT dated November 30, 2016 on regulations on electricity transmission system and Circular No. 39/2015/TT-BCT dated November 18, 2015 on regulations on electricity distribution system

1. To amend Clause 7 Article 1 as follows:

“7. To amend and supplement Clause 1 Article 31 as follows:

1. The customer using transmission grid shall be responsible for investing, installing and managing the information system under his/her scope of management and ensuring it is connected to the information system belonging to the transmission network operator and the dispatching level with control authority as well as the telecommunication and data transmission (including data of SCADA system, PMU and fault recording management) are sufficient, reliable and uninterrupted for electricity system and market operation. Means of communications serving dispatching and operation in the electricity transmission system includes at least direct communication channel, telephone, DIM and Internet.”.

2. To amend Clause 10 Article 1 as follows:

“10. To amend Clause 2 Article 37 as follows:

2. Requirements for connection of Control Center

a) Requirements for connection to information system

- There is one data transmission line to be connected to the information system of the dispatching level with control authority. If multiple dispatching levels with control authority exist, an information sharing method must be agreed by all the dispatching levels;

- There are two data transmission lines (one operating and one backup) to be connected to the control and information system of power plants, substations remotely controlled by the Control Center;

- Means of communications serving dispatching between the dispatching levels with control authority and the Control Center includes at least direct communication channel, telephone, DIM and Internet. Means of communications between the Control Center and power plants, substations includes at least direct communication channel, telephone and Internet.

b) Requirements for connection to SCADA system

- There is one port connecting to SCADA system of the dispatching level with control authority. If multiple dispatching levels with control authority exist, all the dispatching levels shall share information;

- There are two ports connecting to RTU or Gateway, control system of power plants, substations and switchgears on the electrical grid remotely controlled by the Control Center.

c) The Control Center must install a monitoring screen connected to the surveillance camera system at power plants, substations.”.

3. To amend Clause 11 Article 1 as follows:

“11. To amend Clause 3 Article 38 as follows:

3. Generating sets of a power plant shall be capable of adjusting the primary frequency as the frequency drops out of the governor dead-band as well as meeting at least 50% of the primary frequency adjusting capacity of the generating sets in the first 15 seconds, 100% of the primary frequency adjusting capacity of the generating sets in 30 seconds and maintaining such capacity at least the next 15 seconds. The primary frequency adjusting capacity of the generating set shall be calculated according to the actual frequency deviation, the remaining available capacity of the generating set, limit of primary responsiveness according to the generating set’s technology and settings required by the electricity system and market operator.”.

4. To amend Clause 12 Article 1 as follows:

“12. To amend Article 42 as follows:

Article 42. Technical requirements of wind and solar power plants

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

a) Free generation mode: Generation of possible maximum power in accordance with change of primary sources (wind or solar);

b) Generating capacity control mode:

Wind and solar power plants shall be capable of adjusting generating power according to dispatch instruction as follows:

- Generation of possible maximum power in case primary sources are lower than limited value of dispatch instruction; 

- Generation of power in accordance with dispatch instruction with the tolerance within ± 01 % of rated power in case primary sources are equal or greater than value than limited value of dispatch instruction.

2. Wind and solar power plants at every time of connection to the grid shall be capable of maintaining generation of power for a minimum period of time in proportion to working frequency band prescribed in Table 8 below:

Table 8

Minimum time to maintain power generation in proportion to frequency band of electricity system of wind or solar power plants

3. When the electricity system’s frequency is greater than 50.5 Hz, wind and solar power plants may reduce active power with the droop characteristics ranging from 2% to 10%. The setting value of droop characteristics shall be calculated and determined by the dispatching level with control authority. Such processing of reducing active power must be recorded the stating of reduction no later than 02 seconds after the frequency is greater than 50.5 Hz and completed within 15 seconds.

 4. Wind and solar power plants shall be capable of adjusting reactive power as described by the graph below and at Point a, b of this Clause:

             a) If a power plant generates an active power greater or equal to 20% of rated active power and voltage at the high-voltage side of its step-up transformer varies within ± 10 % of nominal voltage, such power plant shall be capable of adjusting reactive power continuously in a power factor from 0.95 (corresponding to reactive power generation mode) to 0.95 (corresponding to reactive power receiving mode) at the high-voltage side of its step-up transformer or at the reactive power separation measurement point of each plant in case of many plants all connected to a step-up transformer corresponding to the rated capacity;

b) If a power plant generates an active power of less than 20% of rated power, such power plant shall reduce the ability to receive or generate reactive power in accordance with its characteristics.

5. Control mode of voltage and reactive power:

a) Wind and solar power plants shall be capable of adjusting voltage and reactive power in the following modes:

- Voltage control mode according to voltage setting value, voltage adjustment droop characteristics (voltage/reactive power characteristics);

- Control mode according to the value of reactive power setting;

- Control mode according to the power factor.

b) If voltage at the high-voltage side of step-up transformer of a power plant varies within ± 10 % of nominal voltage, the wind or solar power plant shall be capable of adjusting voltage at the low-voltage side of the step-up transformer with deviation no more than ± 0.5 % of rated voltage (compared to the voltage setting) whenever the reactive power of the generating set is still within the permissible working band and completed for no more than 05 seconds.

6. At every time of connection to the grid, wind and solar power plants shall be capable of maintaining generation of power in proportion to voltage band at the high-voltage side of their step-up transformer in the time as follows:

a) Voltage less than 0.3 pu, minimum time is 0.15 seconds;

b) Voltage from 0.3 pu to under 0.9 pu, minimum time is calculated in following formula:

T_min = 4 x U - 0.6

In which:

- T_min (second): Minimum time to maintain power generation;

- U (pu): Actual voltage at the high-voltage side of step-up transformer of the power plant (pu);

c) Voltage from 0.9 pu to under 1.1 pu, wind and solar power plants shall maintain continuous generation;

d) Voltage from 1.1 pu to under 1.15 pu, wind and solar power plants shall maintain generation for 03 seconds;

dd) Voltage from 1.15 pu to under 1.2 pu, wind and solar power plants shall maintain generation for 0.5 seconds.

7. Phase unbalance, total harmonic distortion and flicker perceptibility caused by wind and solar power plants at the high-voltage side of step-up transformer of the power plants shall not be allowed to exceed the values prescribed in Articles 7, 8 and 9 herein.

8. Wind and solar power plants shall invest in equipment and adjusting systems which automatically ensure a stable, reliable and secured connection to the Automatic Generation Control (AGC) system of the electricity system and market operator for remotely adjusting the capacity of such plants through the dispatch instruction by such electricity system and market operator.

9. Wind and solar power plants must maintain the connection to the grid when the power system frequency is varied in the range from 0 Hz/second to 01 Hz/second measured within a 500-millisecond time frame.

10. In case voltage at the high-voltage side of step-up transformer of a power plant is outside ± 10 % of nominal voltage, the power plant shall be capable of setting the priority mode of either generating reactive current (upon low voltage) or absorbing reactive current (upon high voltage) to support the electricity system during the incident, the reactive current may vary from 0 % to 10 % of rated current of the plant for every change of 01% voltage with the permissible tolerance of at most 20% (the rate of change shall be determined by the dispatching level with control authority), and completion time is no more than 100 milliseconds.

11. After the incident is cleared and the electricity system returns to the normal operation mode, the power plant must ensure that:

a) The power plant shall be capable of restoring the active power to return to the operation mode before the incident with the active power increase of at least 30 % of rated capacity per second and at most 200 % of rated capacity per second;

b) If sets of wind turbines or inverters of a solar power plant are shut down in case an electricity system incident lasts longer than the minimum grid connection time as required, the reconnection of such sets must be carried out no earlier than 03 minutes after the electricity system returns to normal operation status with the active power recovery of at most 10 % of rated capacity per minute.

12. A power plant must maintain grid connection in case an instantaneous phase swing of up to 20 degrees within 100 milliseconds is made at the voltage at the high-voltage side of its step-up transformer without causing any generation interruption or generating capacity reduction”.

5. To amend Clause 17 Article 1 as follows:

“17. To amend Article 73 as follows:

Article 73. Technical requirements of ancillary services

1. Secondary regulation: Generating sets, power plants providing secondary regulation service shall be capable of starting to provide frequency regulation power within 20 seconds after receiving an AGC signal from the electricity system and market operator and fully provide secondary regulation power as registered within 10 minutes and maintaining such power for a minimum of 15 minutes.

2. Quick-start: Generating sets, power plants providing quick-start reserve shall be capable of increasing to the rated power within 25 minutes and maintaining such rated power for a minimum of 08 hours.

3. Voltage adjustment: Generating sets, power plants providing voltage adjustment shall be capable of changing reactive power outside the adjustment band as prescribed in Clause 2 Article 38 and Clause 4 Article 42 herein, meeting requirements of the electricity system and market operator.

4. Must-run operation reserves to ensure electricity system security: Generating sets, power plants providing must-run operation to ensure electricity system security shall be capable of increasing to a rated power within one hour and maintaining such rated power for a minimum of 08 hours (excluding the time of starting).

5. Black start: Generating sets, power plants providing black start shall be capable of self-starting in a cold state without power supply from the national electricity system and capable of connecting and supplying power to the electricity system after being successfully started.”.

6. To amend Clause 18 Article 1 as follows:

“18. To amend Article 74 as follows:

Article 74: Determining demand for and operating ancillary services

1. General principles of determining demand for ancillary services:

a) Maintain electrical energy and capacity reserves of the electricity system in order to meet electricity system operation and security standards;

b) Ensure minimum expenses in accordance with conditions and obligations of the national electricity system.

2. The electricity system and market operator and the Vietnam Electricity shall be responsible for calculating and submitting the demand for ancillary services of the national electricity system according to the Procedures for determining demand for and operating ancillary services issued by the Electricity Regulatory Authority.”.

7. To amend Clause 10 Article 2 as follows:

“10. To amend Clause 1 and Clause 2 Article 38 as follows:

1. Power plants connected to the distribution grid with the capacity of at least 10 MW (regardless of the voltages at connection point) and 110 kV transformers which is not yet connected to the Control Center shall be equipped with a Gateway or RTU with two ports physically connecting independently to the SCADA system of the dispatching level with control authority.In case of multiple dispatching levels with control authority for a power plant or transformer, all the dispatching levels shall share information for coordination in operating the electricity system.

2. Power plants connected to the distribution grid with the capacity of at least 10 MW which is connected to the Control Center must be equipped a Gateway or RTU with one port connecting to the SCADA system of the dispatching level with control authority and two ports connecting to the controlling system at the Control Center. 110 kV transformers which is controlled and remotely manipulated from the Control Center shall be equipped with a Gateway or RTU with two ports connecting to the controlling system at the Control Center and the Control Center shall share the information to the dispatching level with control authority.”.

8. To amend Clause 11 Article 2 as follows:

“11. To amend and supplement Article 40 as follows:

Article 40. Technical requirements of wind and solar power plants with the capacity of more than 1 MW connected to power distribution grids at the medium voltage or more

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

a) Free generation mode: Generation of possible maximum power in accordance with change of primary sources (wind or solar);

b) Generating capacity control mode:

Wind and solar power plants shall be capable of adjusting generating power according to dispatch instruction as follows:

- Generation of possible maximum power in case primary sources are lower than limited value of dispatch instruction;

- Generation of power in accordance with dispatch instruction within ± 01% of rated power in case primary sources are equal or greater than value than limited value of dispatch instruction.

2. Wind and solar power plants at every time of connection to the grid shall be capable of maintaining generation of power for a minimum period of time in proportion to working frequency band prescribed in Table 5b below:

Table 5b:

Minimum time to maintain power generation in proportion to frequency band of electricity system of wind or solar power plants

3. When the electricity system’s frequency is greater than 50.5 Hz, wind and solar power plants may reduce active power with the droop characteristics ranging from 2% to 10%. The setting value of droop characteristics shall be calculated and determined by the dispatching level with control authority. Such processing of reducing active power must be recorded the stating of reduction no later than 02 seconds after the frequency is greater than 50.5 Hz and completed within 15 seconds.

 4. Wind and solar power plants shall be capable of adjusting reactive power as described by the graph below and at Point a, b of this Clause:

a) If a power plant generates an active power greater or equal to 20 % of rated active power and voltage at the high-voltage side of its step-up transformer varies within ± 10 % of nominal voltage, such power plant shall be capable of adjusting reactive power continuously in a power factor from 0.95 (corresponding to reactive power generation mode) to 0.95 (corresponding to reactive power receiving mode) at the high-voltage side of its step-up transformer or at the reactive power separation measurement point of each plant in case of many plants all connected to a step-up transformer corresponding to the rated capacity;

b) If a power plant generates an active power of less than 20 % of rated power, such power plant shall reduce the ability to receive or generate reactive power in accordance with its characteristics.

5. Control mode of voltage and reactive power:

a) Wind and solar power plants shall be capable of adjusting voltage and reactive power in the following modes:

- Voltage control mode according to voltage setting value, voltage adjustment droop characteristics (voltage/reactive power characteristics);

- Control mode according to the value of reactive power setting;

- Control mode according to the power factor;

b) If voltage at the high-voltage side of step-up transformer of a power plant varies within ± 10 % of nominal voltage, the wind or solar power plant shall be capable of adjusting voltage at the low-voltage side of the step-up transformer with deviation no more than ± 0.5 % of rated voltage (compared to the voltage setting) whenever the reactive power of the generating set is still within the permissible working band and completed in no more than 05 seconds.

6. At every time of connection to the grid, wind and solar power plants shall be capable of maintaining generation of power in proportion to voltage band at the high-voltage side of their step-up transformer in the time as follows:

a) Voltage less than 0.3 pu, minimum time is 0.15 seconds;

b) Voltage from 0.3 pu to under 0.9 pu, minimum time is calculated in following formula:

T_min = 4 x U - 0.6

In which:

- T_min (second): Minimum time to maintain power generation;

- U (pu): Actual voltage at the high-voltage side of step-up transformer of the power plant (pu);

c) Voltage from 0.9 pu to under 1.1 pu, wind and solar power plants shall maintain continuous generation;

d) Voltage from 1.1 pu to under 1.15 pu, wind and solar power plants shall maintain generation for 03 seconds;

dd) Voltage from 1.15 pu to under 1.2 pu, wind and solar power plants shall maintain generation for 0.5 seconds.

7. Phase unbalance, total harmonic distortion and flicker perceptibility caused by wind and solar power plants at the high-voltage side of step-up transformer of the power plants shall not be allowed to exceed the values prescribed in Articles 6, 7 and 8 herein.

8. Wind and solar power plants shall invest in equipment and adjusting systems which automatically ensure a stable, reliable and secured connection to the Automatic Generation Control (AGC) system of the dispatching level with control authority for remotely adjusting the capacity of such plants through the dispatch instruction by the dispatching level with control authority.

9. Wind and solar power plants must maintain the connection to the grid when the power system frequency is varied in the range from 0 Hz/second to 01 Hz/second measured within a 500-millisecond time frame.

10. In case voltage at the high-voltage side of step-up transformer of a power plant is outside ± 10 % of nominal voltage, the power plant shall be capable of giving a priority to either generate reactive current (upon low voltage) or absorb reactive current (upon high voltage) to support the electricity system during the incident, the reactive current may vary from 0 % to 10 % of rated current of the plant for every change of 01% voltage with the permissible tolerance of at most 20% (the rate of change shall be determined by the dispatching level with control authority), and completion time is no more than 100 milliseconds.

11. After the incident is cleared and the electricity system returns to the normal operation mode, the power plant must ensure that:

a) The power plant shall be capable of restoring the active power to return to the operation mode before the incident with the active power increase of at least 30 % of rated capacity per second and at most 200 % of rated capacity per second;

b) If sets of wind turbines or inverters of a solar power plant are shut down in case an electricity system incident lasts longer than the minimum grid connection time as required, the reconnection of such sets must be carried out no earlier than 03 minutes after the electricity system returns to normal operation status with the active power recovery of at most 10 % of rated capacity per minute.

12. A power plant must maintain grid connection in case an instantaneous phase swing of up to 20 degrees within 100 milliseconds is made at the voltage at the high-voltage side of its step-up transformer without causing any generation interruption or generating capacity reduction”.

9. To amend Clause 13 Article 2 as follows:

“13. To amend Clause 2 Article 42 as follows:

2. Requirements for connection of Control Center

a) Requirements for connection to information system:

- There is one data transmission line to be connected to the information system of the dispatching level with control authority. If multiple dispatching levels with control authority exist, an information sharing method must be agreed by all the dispatching levels;

- There are two data transmission lines (one operating and one backup) to be connected to the control and information system of power plants, substations remotely controlled by the Control Center;

- Means of communications serving dispatching between the dispatching levels with control authority and the Control Center includes at least direct communication channel, telephone, DIM and Internet. Means of communications between the Control Center and power plants, substations includes at least direct communication channel, telephone and Internet.

b) Requirements for connection to SCADA system:

- There is one port connecting to SCADA system of the dispatching level with control authority. If multiple dispatching levels with control authority exist, all the dispatching levels shall share information;

- There are two ports connecting to RTU or Gateway, control system of power plants, substations and switchgears on the electrical grid remotely controlled by the Control Center.

c) The Control Center must install a monitoring screen connected to the surveillance camera system at power plants, substations.”.

Article 2. Amending and supplementing a number of articles of the Minister of Industry and Trade’s Circular No. 25/2016/TT-BCT dated November 30, 2016 on regulations on electricity transmission system

1. To amend and supplement Clause 16 Article 3 as follows:

“16. Transmission network operator means an electricity unit that is granted the operation license in electricity transmission.”.

2. To add Point d Clause 1 Article 37 as follows:

“d) The total rated capacity of power plants under the Control Center shall not exceed the rated capacity of the largest generating set currently generating electricity in the national electricity system as determined by the electricity system and market operator.”.

3. To amend and supplement Clause 1 Article 38 as follows:

“1. Power plants with installed capacity of over 30 MW must be equipped with facilities, adjusting systems, AGC system which ensure a stable, reliable and secured connection to automatic generation control system of the electricity system and market operator for remotely adjusting the capacity of such generating sets through the dispatch instruction by such electricity system and market operator. For power plants in industrial parks that only sell part of their output to the national electricity system, the necessity of equipping AGC system must be agreed upon by the parties and clearly stated in the connection agreement. Particular technical requirements for connection of the generating set's AGC system to SCADA/EMS of the electricity system and market operator are prescribed in the regulation on technical and operation requirements of SCADA system issued by the Electricity Regulatory Authority.”.

4. To add Clause 8 Article 38 as follows:

“8. Generating sets of power plants must maintain the connection to the grid when the power system frequency is varied in the range from 0 Hz/second to 01 Hz/second measured within a 500-millisecond time frame.”.

5. To amend the title of Article 46 as follows:

“Article 46. Provision of dossiers for inspection of conditions for energizing connection points for trial run and acceptance test”.

6. To amend and supplement the first bullet point at Point c Clause 1 Article 46 as follows:

“- Technical parameters of equipment including parameters of connection lines;”.

7. To amend the title of Article 47 as follows:

“Article 47. Inspection of conditions for energizing connection points for trial run and acceptance test”.

8. To amend and supplement Clause 2 Article 47 as follows:

“2. The transmission network operator shall be responsible for reaching an agreement with its customers on procedures for inspection of dossiers, acceptance records and actual installation of equipment under the connection agreement.”.

9. To amend the title of Article 48 as follows:

“Article 48. Energizing connection points for trial run and acceptance test”.

10. To amend and supplement Point a Clause 1 Article 48 as follows:

“a) Legal and technical documents of a work:

- The customer’s written confirmation and commitment on equipment within the scope of energizing that meets operational and technical requirements as agreed at connection points and fully complies with law provisions after testing and examination for such equipment are conducted;

- Copy of the written record of inspection of conditions for energizing connection points with content on satisfaction of all requirements in the connection agreement;

- Measurement system completed as prescribed, electrical meter indicators finalized;

- Signed power purchase agreement or any agreement for power purchase, delivery;”.

11. To amend and supplement Clause 5 Article 49 as follows:

“5. Electrical grid, power plant and electrical equipment after the connection point of the customer shall be put into official operation after the testing, partial and full acceptance are completed with sufficient written records and requirements prescribed herein and provisions on planning, land, construction, fire prevention and fighting, environment and relevant laws are observed.”.

12. To amend the title of Article 52 as follows:

“Article 52. Provision of dossiers for inspection of conditions for energizing connection points of equipment of transmission network operators for trial run and acceptance test”.

13. To amend Point dd Clause 1 Article 52 as follows:

“dd) Diagrams detailing plan on connection to electrical works of the transmission network operator and parameters of connection lines;”.

14. To amend the title of Article 53 as follows:

“Article 53. Energizing connection points of equipment of transmission network operators for trial run and acceptance test”.

15. To amend and supplement Point a Clause 1 Article 53 as follows:

“a) Legal and technical documents:

- The project owner’s written confirmation and commitment on equipment within the scope of energizing that meets operational and technical requirements at connection points and fully complies with law provisions after testing and examination for such equipment are conducted;

- Measurement system completed as prescribed, electrical meter indicators finalized;”.

16. To amend and supplement Clause 4 Article 59 as follows:

 “4. The electricity transmission system shall operate in an extreme emergency mode under one of following conditions:

a) Electricity system frequency is outside permissible band in case of a single fault in the electricity system as prescribed in Article 4 herein or the frequency continues to be dropped below 49.5Hz after all reserve power has been mobilized; 

b) Load carrying level of any equipment in the transmission grid or equipment connecting to the transmission grid is equal to 110% of rated value or more and when an incident caused by an overload to such equipment may result in disintegration of individual components of the electricity system;

c) The high reduction of any voltage level on the transmission grid results in operation of the under-low voltage load shedding relay; the voltage level on the transmission grid is lower than 10% of the nominal voltage or there is a risk of voltage collapse in the electricity system as calculated by the dispatching level in case there is no adjustment measure other than load shedding and the high reduction voltage tends to be continued.”.

17. To add Point dd Clause 3 Article 60 as follows:

“dd) Requirements for minimum source mobilization configuration and minimum inertia in the electricity system to ensure safe operation of the electricity system.”.

18. To amend and supplement Clause 3 Article 62 as follows:

“3. Generating units shall be responsible for operating power plants to maintain adjusting working voltage level and ensuring adequate supply of reactive power to the electricity system during operation; not separating generating sets from the operation in case of a fault unless such fault runs the risk of threatening human lives or safety of the equipment or the frequency exceeds permissible limits prescribed in Articles 38 and 42 herein or permitted by the electricity system and market operator.”.

19. To amend and supplement Points a and c Clause 3 Article 64 as follows:

“a) Change generating capacity of the generating set, stop or start the generating set to restore the electricity system to normal operation mode;

c) The automatic load shedding system must be arranged and installed appropriately to prevent the electricity system from falling into pieces in case of incident.  The electricity system and market operator shall be responsible for determining installation positions and settings of the protection relays to carry out load shedding in case of incident in the electricity system to ensure the safety and security of the electricity system;”.

Article 3. Amending and supplementing a number of articles of the Minister of Industry and Trade’s Circular No. 39/2015/TT-BCT dated November 18, 2015 on regulations on electricity distribution system

1. To amend and supplement Clause 1 Article 37 as follows:

“1. Power plants connected to the distribution grid with the capacity of at least 10 MW or 110 kV transformers must be equipped the information system and it must be connected compatibly to the information system belonging to the dispatching levels with control authority for the telecommunication and data transmission in electricity system operation. Means of communications serving dispatching includes at least direct communication channel, telephone, DIM and Internet.”.

2. To add Point e Clause 2 Article 39 as follows:

“e. Generating sets of power plants must maintain the connection to the grid when the power system frequency is varied in the range from 0 Hz/second to 01 Hz/second measured within a 500-millisecond time frame.”.

3. To add Article 40a after Article 40 as follows:

“Article 40a. Requirements for wind, solar power sources with capacity of 1 MW or fewer connected to the medium-voltage grid

1. At every time of connection to the grid, wind, solar power sources shall be capable of maintaining generation of power for a minimum period of time in proportion to working frequency band prescribed in Table 5c below:

Table 5c.

Minimum time to maintain power generation in proportion to frequency band of electricity system

2. In case the electricity system frequency is greater than 50.5 Hz, wind, solar power sources must reduce the active power according to the following formula:

In which:

- ΔP: Level of active power reduction (MW);

- P_m: Active power in proportion to the point of time prior to power reduction (MW);

- f_n: Electricity system frequency prior to power reduction (Hz).

3. Wind, solar power sources shall be capable of maintaining continuous generation of power within the voltage ranges at connection points as prescribed in Table 5d below: 

Table 5d.

Minimum time to maintain power generation in proportion to voltage ranges at connection points

4. Wind, solar power sources shall not cause penetration of direct current into the distribution grid of exceeding 0.5% of the rated current at the connection point.

5. Wind, solar power sources must comply with regulations on voltage, phase balance, harmonics, flicker perceptibility and grounding as prescribed in Articles 5, 6, 7, 8 and 10 herein.

6. Wind, solar power sources shall be equipped with protective equipment meeting the following requirements:

a) Disconnect itself from the distribution grid when there is a fault within the wind, solar power sources;

b) Disconnect itself when power failure occurs in the distribution grid and not generate power when the distribution grid is out of power;

c) Not automatically reconnect to the grid if the following conditions are not satisfied:

- The frequency of the grid shall be maintained from 48Hz to 51Hz for at least 60 seconds;

- Voltage of all phases at connection point shall be maintained from 85% to 110% of rated voltage for at least 60 seconds.

d) Customers who request connection shall negotiate and agree on the protection system requirements with the electricity distributor, in which at least protections specified at Points a, b, c of this Clause, overvoltage protection, undervoltage protection and frequency protection shall be included.

7. Addition to requirement specified in Clauses 1 to 6 of this Article, wind, solar power sources with capacity of 100 kW to 1 MW connected to the medium-voltage grid must satisfy the following technical requirements:

a) The reactive power control mode must be activated under the control mode according to the power factor with the Cos Phi set under the request of the dispatching levels with control authority, except otherwise agreed on with the dispatching levels with control authority;

b) Being capable of setting the priority mode of generating either active power or reactive power at the request of the dispatching levels with control authority when the voltage at the connection point is outside the voltage range subject to continuous operation specified Clause 3 of this Article.

8. Project owners of wind, solar power sources connected to the medium-voltage grid with capacity of 100 kW to 1 MW shall be responsible for agreeing with the electricity distributors upon equipment and means connected with the dispatching level of distribution’s collection, monitoring and control system.”

4. To add Point d Clause 1 Article 42 as follows:

“d) The total rated capacity of power plants under the Control Center shall not exceed the rated capacity of the largest generating set currently generating electricity in the national electricity system as determined by the electricity system and market operator.”.

5. To amend the title of Article 47 as follows:

“Article 47. Provision of dossiers for inspection of conditions for energizing connection points for trial run and acceptance test for customers using distribution grid and proposing connection at 110 kV, and customers owning generating sets and proposing connection at medium voltage”.

6. To amend the title of Article 48 as follows:

“Article 48. Provision of dossiers for inspection of conditions for energizing connection points for trial run and acceptance test for electricity customers with separate power stations connected to the medium-voltage grid”.

7. To amend the title of Article 49 as follows:

“Article 49. Inspection of conditions for energizing connection points for testing and acceptance”.

8. To amend and supplement Clause 3 Article 49 as follows:

“3. The electricity distributor shall be responsible for reaching an agreement with its customers on procedures for inspection of dossiers, acceptance records and actual installation of equipment under the connection agreement.”.

9. To amend the title of Article 50 as follows:

“Article 50. Energizing connection points for trial run and acceptance test”.

10. To amend and supplement Point a Clause 1 Article 50 as follows:

“a) Legal and technical documents:

- The customer’s written confirmation and commitment on equipment within the scope of energizing that meets operational and technical requirements at connection points and fully complies with law provisions after testing and examination for such equipment are conducted;

- Copy of the written record of inspection of conditions for energizing connection points with content on satisfaction of all requirements in the connection agreement;

- Measurement system completed, electrical meter indicators finalized;

- Signed power purchase agreement or any agreement for power purchase, delivery;”.

11. To add Clause 4 Article 50 as follows:

“4. An electricity customer connecting to the medium-voltage grid is allowed to energize connection points right after the inspection of conditions for energizing connection point is completed with a written record confirming the observance with requirements stated in the connection agreement and satisfaction of all legal, technical, dispatching and operation requirements specified in Clause 1 of this Article and electrical safety.”.

12. To amend and supplement Point d Clause 1 Article 51 as follows:

“d) Electrical grid, power plant and electrical equipment after the connection point of the customer shall be put into official operation after the testing, partial and full acceptance are completed with sufficient written records and requirements prescribed herein and provisions on planning, land, construction, fire prevention and fighting, environment and relevant laws are observed.”.

13. To amend the title of Article 55 as follows:

“Article 55. Provision of dossiers for inspection of conditions for energizing connection points of equipment of electricity distributor for trial run and acceptance test”.

14. To amend the title of Article 56 as follows:

“Article 56. Energizing connection points of equipment of electricity distributors for trial run and acceptance test”.

15. To amend and supplement Point a Clause 1 Article 56 as follows:

“a) Legal and technical documents:

- The project owner’s written confirmation and commitment on equipment within the scope of energizing that meets operational and technical requirements at connection points and fully complies with law provisions after testing and examination for such equipment are conducted;

- Measurement system completed, electrical meter indicators finalized;”.

16. To amend and supplement Clause 1 Article 62 as follows:

“1. Manage and operate electrical equipment and electrical grid within their management, ensuring the satisfaction of operational and technical requirements defined herein, observance of Procedures for dispatching of national electricity system, Procedures for operation in the national electricity system, Procedures for handling of incidents in the national electricity system issued by the Ministry of Industry and Trade and other relevant laws.”.

17. To amend and supplement Point a Clause 1 Article 64 as follows:

“a) Manage and operate electrical equipment and electrical grid within their management, ensuring the satisfaction of operational and technical requirements defined herein, observance of Procedures for dispatching of national electricity system, Procedures for operation in the national electricity system, Procedures for handling of incidents in the national electricity system issued by the Ministry of Industry and Trade and other relevant laws;”.

18. To add Clause 2a after Clause 2 Article 100 as follows:

“2a. Departments of Industry and Trade of provinces and centrally-run cities shall be responsible for inspecting and supervising the observance of this Circular within their management areas.”.

Article 4. Implementation provisions

1. This Circular takes effect on February 16, 2023.

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

a) To repeal the second bullet point at Point a Clause 3 Article 92 and Clause 2 Article 94 of the Minister of Industry and Trade’s Circular No. 25/2016/TT-BCT dated November 30, 2016 on regulations on electricity transmission system;

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

3. For electrical equipment with requirements or specifications different from provisions of this Circular that has been put into operation or of which the equipment installation or purchase contract has been signed before the effective date of this Circular, the units shall comply with the relevant regulations applicable before the effective date of this Circular.

4. Any difficulty and problem arising in the course of implementation should be promptly reported to the Electricity Regulatory Authority of Vietnam for considering and handling within its competence or reporting to the Ministry of Industry and Trade for settlement./.