Circular 39/2022/TT-BCT amends and supplements certain Articles of Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade stipulating the transmission power system; Circular No. 39/2015/TT-BCT dated November 18, 2015 of the Minister of Industry and Trade stipulating the distribution power system; and Circular No. 30/2019/TT-BCT dated November 18, 2019 amending and supplementing certain Articles of Circular No. 25/2016/TT-BCT dated November 30, 2016 of the Minister of Industry and Trade stipulating the transmission power system and Circular No. 39/2015/TT-BCT dated November 18, 2015 of the Minister of Industry and Trade stipulating the distribution power system.

CIRCULAR

Amending and supplementing certain Articles of Circular No. 25/2016/TT-MININD dated November 30, 2016 of the Minister of Industry and Trade stipulating the transmission power system, Circular No. 39/2015/TT-MININD dated November 18, 2015 of the Minister of Industry and Trade stipulating the distribution power system, and Circular No. 30/2019/TT-MININD dated November 18, 2019 amending and supplementing certain articles of Circular No. 25/2016/TT-MININD dated November 30, 2016 of the Minister of Industry and Trade stipulating the transmission power system and Circular No. 39/2015/TT-MININD dated November 18, 2015 of the Minister of Industry and Trade stipulating the distribution power system

Pursuant to the Electricity Law promulgated on December 3, 2004; The Law Amending and Supplementing Certain Provisions of the Electricity Law promulgated on November 20, 2012 and The Law Amending and Supplementing Certain Provisions of the Public Investment Law, the Public-Private Partnership Investment Law, the Investment Law, the Housing Law, the Bidding Law, the Electricity Law, the Enterprise Law, the Special Consumption Tax Law, and the Civil Enforcement Law promulgated on January 11, 2022;

Decree No. 96/2022/NĐ-CP dated 29 the 11 Pursuant to Decree No. 32/2019/NĐ-CP dated April 10, 2019 of the Government on assigning tasks, procurement or tendering for the supply of products and services using state budget from regular operating expenses;22 /NĐ-CP dated March

Based on Decree No. 137/2013/NĐ-CP dated October 21, 2013, issued by the Government, detailing the implementation of certain provisions of the Electricity Law and the Law Amending and Supplementing Certain Provisions of the Electricity Law;

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

The Minister of Industry and Trade issues this Circular amending and supplementing certain provisions of Circular No. 25/2016/TT-MININD dated November 30, 2016 of the Minister of Industry and Trade stipulating the transmission power system; Circular No. 39/2015/TT-MININD dated November 18, 2015 of the Minister of Industry and Trade stipulating the distribution power system and Circular No. 30/2019/TT-MININD dated November 18, 2019 amending and supplementing certain provisions of Circular No. 25/2016/TT-MININD dated November 30, 2016 of the Minister of Industry and Trade stipulating the transmission power system and Circular No. 39/2015/TT-MININD dated November 18, 2015 of the Minister of Industry and Trade stipulating the distribution power system.

Circular No. 03/2023/TT-BCA Circular No. 30/2019/TT-MININD dated November 18, 2019 amending and supplementing certain provisions of Circular No. 25/2016/TT-MININD dated November 30, 2016 of the Minister of Industry and Trade stipulating the transmission power system and Circular No. 39/2015/TT-MININD dated November 18, 2015 of the Minister of Industry and Trade stipulating the distribution power system

1. Amend Clause 7 of Article 1 as follows:

“7. Amend and supplement Clause 1 of Article 31 as follows:

1. Customers using the transmission grid shall be responsible for investing, installing, managing, and operating the information system within their management scope and ensuring the connection of this system with the information system of the Transmission Unit and the Dispatching Authority with control rights; ensuring communication, data transmission (including data from the SCADA system, PMU, fault recording systems) to be complete, reliable, and continuous to serve the operation of the power system and the electricity market. The minimum communication means serving dispatching and operation work in the transmission power system include direct lines, telephones, DIM, and computer networks.”

2. Amend Clause 10 of Article 1 as follows:

“10. Amend Clause 2 of Article 37 as follows:

2. Connection requirements of the Control Center

a) Information system connection requirements

- One data transmission link connecting to the information system of the Dispatching Authority with control rights. In case there are multiple dispatching authorities with control rights, these authorities shall be responsible for unifying the information sharing method;

- Two data transmission links (one working link and one backup link) connecting to the control and information systems of power plants and substations controlled remotely by the Control Center;

- Minimum communication means serving dispatching work between dispatching authorities with control rights and the Control Center include direct lines, telephones, DIM, and computer networks. Minimum communication between the Control Center and power plants and substations include direct lines, telephones, and computer networks.

b) SCADA system connection requirements

- One connection to the SCADA system of the Dispatching Authority with control rights. In case there are multiple dispatching authorities with control rights, these authorities shall be responsible for sharing information;

- Two connections to the RTU terminal or Gateway, control systems of power plants and substations, and circuit breakers on the grid controlled remotely by the Control Center.

c) The Control Center must be equipped with surveillance screens and connected to security camera systems at power plants and substations.”

3. Amend Clause 11 of Article 1 as follows:

“11. Amend Clause 3 of Article 38 as follows:

3. Power generation units of power plants must have the ability to participate in primary frequency control when the frequency deviates from the deadband of the governor system and must meet at least 50% of the primary frequency control capacity of the unit within the first 15 seconds, 100% of the primary frequency control capacity of the unit within 30 seconds, and maintain this capacity for at least the next 15 seconds. The primary frequency control capacity of the unit is calculated based on actual frequency deviation, remaining available capacity of the unit, primary response capability limit according to the technology of the unit, and settings required by the System Operation and Market Unit.”

4. Amend Clause 12 of Article 1 as follows:

“12. Amend Article 42 as follows:

Article 42. Technical Requirements for Wind Power Plants and Solar Power Plants

1. Wind power plants and solar power plants must be capable of maintaining operation to generate effective capacity under the following modes:

a) Free generation mode: Operating to generate maximum possible electrical capacity according to the primary energy source changes (wind or sun).

b) Generation capacity control mode:

Wind power plants and solar power plants must be able to limit generation capacity according to dispatch orders in the following cases:

- In case the primary energy source fluctuation is lower than the value specified in the dispatch order, generate the maximum possible capacity;

- In case the primary energy source fluctuation is equal to or higher than the value specified in the dispatch order, generate capacity at the value specified in the dispatch order with an error range of ± 01 % of the rated capacity.

2. At all times when connected to the grid, wind power plants and solar power plants must maintain operation to generate electricity for a minimum time corresponding to the frequency ranges as stipulated in Table 8 as follows:

Table 8

Minimum Time to Maintain Operation to Generate Electricity of Wind Power Plants and Solar Power Plants

Corresponding to System Frequency Ranges System Frequency Range

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

a) In case the effective capacity generated by the plant is greater than or equal to 20% of the rated effective capacity and the high-voltage side transformer boost voltage of the power plant is within ± 10 % of the nominal voltage, the power plant must continuously adjust reactive power within the power factor range of 0.95 (corresponding to the reactive power generation mode) to 0.95 (corresponding to the reactive power reception mode) on the high-voltage side of the transformer boost or at the measurement point of each plant's reactive power separation in case multiple plants are connected to one transformer boost corresponding to the rated capacity;

b) In case the effective capacity generated by the plant is less than 20% of the rated capacity, the power plant may reduce its ability to receive or generate reactive power in accordance with the characteristics of the power plant.

5. Voltage Control and Reactive Power Control Mode:

a) Wind power plants and solar power plants must be capable of controlling voltage and reactive power according to the following modes:

- Voltage control mode according to set voltage value, voltage adjustment characteristic (voltage/reactive power relationship characteristic);

- Reactive power control mode according to set reactive power value;

- Power factor control mode.

b) If the high-voltage side transformer boost voltage of the power plant is within ± 10 % of the nominal voltage, wind power plants and solar power plants must be capable of adjusting the low-voltage side transformer boost voltage with a deviation not exceeding ± 0.5 % of the rated voltage (compared to the set voltage value) whenever the generator unit's reactive power remains within the permissible operating range and complete the adjustment within 05 seconds.

6. At all times when connected to the grid, wind power plants and solar power plants must maintain operation to generate electricity corresponding to the high-voltage side transformer boost voltage range of the power plant for the following time periods:

U/Un

b) Voltage from 0.3 pu to below 0.9 pu, the minimum maintenance time is calculated according to the following formula:

= 4 x U - 0.6

T_{Maximum Downhill Gradient} - T (seconds): Minimum generation time;

Where:

- U (pu): Actual voltage at the high-voltage side of the transformer boost of the power plant expressed in per unit (relative units);_{Maximum Downhill Gradient} c) Voltage from 0.9 pu to below 1.1 pu, wind power plants and solar power plants must maintain continuous operation to generate electricity;

d) Voltage from 1.1 pu to below 1.15 pu, wind power plants and solar power plants must maintain operation to generate electricity for 03 seconds;

đ) Voltage from 1.15 pu to below 1.2 pu, wind power plants and solar power plants must maintain operation to generate electricity for 0.5 seconds.

7. Phase imbalance, total harmonic distortion, and voltage flicker levels caused by wind power plants and solar power plants at the high-voltage side of the transformer boost must not exceed the values prescribed in Articles 7, 8, and 9 of this Circular.

8. Wind power plants and solar power plants must invest in equipment, control systems, and automatic systems to ensure stable, reliable, and secure connection with the Automatic Generation Control (AGC) system of the System Operator and Electricity Market to serve remote control of plant capacity according to dispatch orders from the System Operator and Electricity Market.

9. Wind power plants and solar power plants must maintain grid connection when the rate of change of system frequency is within the range of 0 Hz/second to 01 Hz/second measured over a 500-microsecond timeframe.

8. Wind power plants and solar power plants must invest in equipment and control systems to ensure stable, reliable, and secure connection with the automatic generation control (AGC) system of the System Operation Unit and electricity market for remote control of plant capacity according to dispatch orders from the System Operation Unit and electricity market.

9. Wind power plants and solar power plants must maintain grid connection when the rate of change of system frequency varies within the range of 0 Hz/second to 01 Hz/second measured over a time frame of 500 milliseconds.

10. When the voltage at the high-voltage side of the power transformer of the power plant exceeds the nominal voltage range by ± 10%, the power plant must be capable of establishing a priority mode to generate reactive current (when voltage is low) or absorb reactive current (when voltage is high) to support the electrical system during faults. The reactive current can vary from 0% to 10% of the rated power plant capacity for each 1% change in voltage with an error not exceeding 20% (the rate of change is determined by the dispatch authority), and the response time must not exceed 100 milliseconds.

11. After the fault has been eliminated and the electrical system returns to normal operating conditions, the power plant must ensure:

a) The power plant must be able to restore active power to return to the pre-fault operating condition at a rate of increasing active power not less than 30% of the rated capacity within 1 second and not more than 200% of the rated capacity within 1 second;

b) In cases where wind turbine units or solar inverters of the power plant stop operating due to a system fault lasting longer than the minimum grid connection time requirement, the reconnection process of these units must not occur earlier than 3 minutes after the electrical system returns to normal operation, and the rate of restoring active power must not exceed 10% of the rated capacity per minute.

12. The power plant must maintain grid connection when the voltage at the high-voltage side of the power transformer of the power plant experiences instantaneous phase angle voltage swing (Phase Swing) up to 20 degrees within a period of 100 milliseconds without interruption of power generation or reduction in power output.

5. Amend Clause 17 of Article 1 as follows:

"17. Amend Article 73 as follows:

Article 73. Technical requirements for ancillary services

1. Secondary frequency regulation: Generating units, power plants providing secondary frequency regulation services must be capable of starting to supply frequency regulation power within 20 seconds from receiving the AGC signal from the System Operator and Electricity Market, and supplying the entire registered secondary frequency regulation power within 10 minutes and maintaining this level of power for a minimum of 15 minutes.

2. Rapid start-up reserve: Generating units, power plants providing rapid start-up reserve must be capable of reaching full rated power within 25 minutes and maintaining this level of power for a minimum of 8 hours.

3. Voltage regulation: Generating units, power plants providing voltage regulation services must be capable of changing reactive power outside the adjustment range specified in Clause 2 of Article 38 and Clause 4 of Article 42 of this Circular, meeting the requirements of the System Operator and Electricity Market.

4. Operating reserve to ensure system security: Generating units, power plants providing operating reserve to ensure system security must be capable of reaching full rated power within 1 hour and maintaining this level of rated power for a minimum of 8 hours (excluding start-up time).

5. Black start: Generating units, power plants providing black start services must be capable of self-starting from a cold state without requiring power from the national grid and must be capable of connecting and supplying power to the electrical system after successful start-up."

6. Amend Clause 18 of Article 1 as follows:

"18. Amend Article 74 as follows:"

Article 74: Determination of Demand and Operation of Ancillary Services

1. General principles for determining the demand for ancillary services include:

1. Ensuring the maintenance of reserve power and capacity levels in the power system to meet operational and security standards of the power system;
2. Ensuring minimum costs appropriate to the conditions and constraints within the national power system.

2. The power system operator, electricity market operator, and Vietnam Electricity Corporation shall be responsible for determining and submitting the demand for ancillary services to the national power system according to the Ancillary Service Demand Determination and Operation Process issued by the Electricity Regulatory Authority.

7. Amend Clause 10 of Article 2 as follows:

"10. Amend Clause 1 and Clause 2 of Article 38 as follows:

1. Power plants connected to the distribution grid with a capacity of 10 MW or more (regardless of connection voltage level) and 110 kV substations not yet connected to the Control Center must be equipped with Gateway or RTU and establish two physically independent connections with the SCADA system of the Dispatching Level having control authority. In cases where power plants or substations have multiple dispatching levels with control authority, the dispatching levels shall share information to facilitate coordinated operation of the power system.

2. Power plants connected to the distribution grid with a capacity of 10 MW or more that are already connected to the Control Center must be equipped with Gateway or RTU established with one connection to the SCADA system of the Dispatching Level having control authority and two connections to the control system at the Control Center. 110 kV substations controlled and operated remotely from the Control Center must be equipped with Gateway or RTU established with two connections to the control system at the Control Center, and the Control Center will share information with the Dispatching Level having control authority."

8. Amend Clause 11 of Article 2 as follows:

"11. Amend and supplement Article 40 as follows:

Article 40. Requirements for wind power plants and solar power plants with a capacity greater than 1 MW connected to the distribution grid from medium voltage level upwards

1. Wind power plants and solar power plants must be capable of maintaining operation to generate effective capacity under the following modes:

a) Free generation mode: Operating to generate maximum possible electrical capacity according to the primary energy source changes (wind or sun).

b) Generation capacity control mode:

Wind power plants and solar power plants must be able to limit generation capacity according to dispatch orders in the following cases:

- In case the primary energy source fluctuation is lower than the value specified in the dispatch order, generate the maximum possible capacity;

- In cases where the primary energy source varies by or exceeds the limit value according to the dispatch order, they must generate power at the limit value specified in the dispatch order with an error range of ± 01% of the rated capacity.

2. Wind power plants and solar power plants must maintain the ability to operate and generate power for a minimum time corresponding to the frequency ranges specified in Table 5b as follows:

Table 5b.

Minimum Time to Maintain Operation to Generate Electricity of Wind Power Plants and Solar Power Plants

Corresponding to System Frequency Ranges System Frequency Range

3. When the system frequency exceeds 50.5 Hz, wind power plants and solar power plants must be able to reduce active power output according to the relative slope of the static characteristic curve (droop characteristics) within the range of 02% to 10%. The setting value of the relative slope of the static characteristic curve is calculated and determined by the Dispatching Level having control authority. This process of reducing active power output must start no later than 02 seconds upon detecting the frequency above 50.5 Hz and must be completed within 15 seconds.

a) In case the effective capacity generated by the plant is greater than or equal to 20% of the rated effective capacity and the high-voltage side transformer boost voltage of the power plant is within ± 10 % of the nominal voltage, the power plant must continuously adjust reactive power within the power factor range of 0.95 (corresponding to the reactive power generation mode) to 0.95 (corresponding to the reactive power reception mode) on the high-voltage side of the transformer boost or at the measurement point of each plant's reactive power separation in case multiple plants are connected to one transformer boost corresponding to the rated capacity;

a) In cases where the power plant generates active power output greater than or equal to 20% of the rated active power output and the high-voltage side of the step-up transformer's voltage fluctuates within ± 10% of the nominal voltage, the power plant must continuously adjust reactive power within the range of power factor 0.95 (corresponding to the mode of generating reactive power) to 0.95 (corresponding to the mode of receiving reactive power) on the high-voltage side of the step-up transformer of the power plant or at the point of measurement for separating reactive power of each power plant in cases where multiple power plants are connected to one step-up transformer corresponding to the rated capacity;

b) In cases where the power plant generates active power output less than 20% of the rated capacity, the power plant may reduce its capability to receive or generate reactive power in accordance with the characteristics of the power plant.

a) Wind power plants and solar power plants must be capable of controlling voltage and reactive power according to the following modes:

- Voltage control mode according to set voltage value, voltage adjustment characteristic (voltage/reactive power relationship characteristic);

- Reactive power control mode according to set reactive power value;

- Power factor control mode.

- Power factor control mode;

6. At all times when connected to the grid, wind power plants and solar power plants must maintain operation to generate electricity corresponding to the high-voltage side transformer boost voltage range of the power plant for the following time periods:

U/Un

b) Voltage from 0.3 pu to below 0.9 pu, the minimum maintenance time is calculated according to the following formula:

= 4 x U - 0.6

T_{Maximum Downhill Gradient} - T (seconds): Minimum generation time;

Where:

- U (pu): Actual voltage at the high-voltage side of the transformer boost of the power plant expressed in per unit (relative units);_{Maximum Downhill Gradient} c) Voltage from 0.9 pu to below 1.1 pu, wind power plants and solar power plants must maintain continuous operation to generate electricity;

d) Voltage from 1.1 pu to below 1.15 pu, wind power plants and solar power plants must maintain operation to generate electricity for 03 seconds;

đ) Voltage from 1.15 pu to below 1.2 pu, wind power plants and solar power plants must maintain operation to generate electricity for 0.5 seconds.

7. Phase imbalance, total harmonic distortion, and voltage flicker levels caused by wind power plants and solar power plants at the high-voltage side of the transformer boost must not exceed the values prescribed in Articles 7, 8, and 9 of this Circular.

8. Wind power plants and solar power plants must invest in equipment, control systems, and automatic systems to ensure stable, reliable, and secure connection with the Automatic Generation Control (AGC) system of the System Operator and Electricity Market to serve remote control of plant capacity according to dispatch orders from the System Operator and Electricity Market.

7. Phase imbalance, total harmonic distortion, and voltage flicker caused by wind power plants and solar power plants at the high-voltage side of the step-up transformer of the power plant must not exceed the values prescribed in Articles 6, 7, and 8 of this Circular.

8. Wind power plants and solar power plants must invest in equipment and control systems to ensure stable, reliable, and secure connection with the Automatic Generation Control (AGC) system of the Dispatching Level having control authority to serve remote control of power plant capacity according to the dispatch orders of the Dispatching Level having control authority.

9. Wind power plants and solar power plants must maintain grid connection when the rate of change of system frequency varies within the range of 0 Hz/second to 01 Hz/second measured over a time frame of 500 milliseconds.

10. When the voltage at the high-voltage side of the step-up transformer of the power plant deviates outside the range of ± 10% of the nominal voltage, the power plant must prioritize generating reactive current (when voltage is low) or absorbing reactive current (when voltage is high) to support the system during faults, the reactive current can change from 0% to 10% of the rated current of the power plant for every 01% change in voltage with an error not exceeding 20% (the rate of change is calculated and determined by the Dispatching Level having control authority), the completion time of the response must not be later than 100 microseconds.

11. After the fault has been eliminated and the electrical system returns to normal operating conditions, the power plant must ensure:

a) The power plant must be able to restore active power to return to the pre-fault operating condition at a rate of increasing active power not less than 30% of the rated capacity within 1 second and not more than 200% of the rated capacity within 1 second;

b) In cases where wind turbine units or solar inverters of the power plant stop operating due to a system fault lasting longer than the minimum grid connection time requirement, the reconnection process of these units must not occur earlier than 3 minutes after the electrical system returns to normal operation, and the rate of restoring active power must not exceed 10% of the rated capacity per minute.

12. Power plants must maintain grid connection when the voltage at the high-voltage side of the step-up transformer of the power plant experiences instantaneous phase angle voltage swing (Phase Swing) up to 20 degrees within a period of 100 microseconds without interruption of power generation or reduction in power output."

9. Amend Clause 13 of Article 2 as follows:

"13. Amend Clause 2 of Article 42 as follows:

2. Connection requirements of the Control Center

a) Requirements for information system connection:

- There must be a data transmission link connecting to the information system of the Dispatching Level having control authority. In cases where there are multiple Dispatching Levels with control authority, the dispatching levels shall unify the method of sharing information;

- There must be two data transmission links (one working link, one backup link) connecting to the control and information system of the power plant, substation which is remotely controlled by the Control Center;

- Minimum communication means serving dispatch work between Dispatch Levels with control authority and the Control Center include direct communication, telephone, DIM, computer network. Minimum communication means between the Control Center and power plants, substations include direct communication, telephone, computer network.

b) Requirements for SCADA system connection:

- There must be a connection to the SCADA system of the Dispatch Level with control authority. In cases where there are multiple Dispatch Levels with control authority, these Dispatch Levels have the responsibility to share information;

- Two connections to the RTU terminal or Gateway, control systems of power plants and substations, and circuit breakers on the grid controlled remotely by the Control Center.

c) The Control Center must be equipped with surveillance screens and connected to security camera systems at power plants and substations.”

Article 2. Amend and supplement some articles of Circular No. 25/2016/TT-BCT dated November 30, 2016, issued by the Minister of Industry and Trade on the transmission electricity system.

1. Amend and supplement Clause 16 of Article 3 as follows:

“16. Transmission electricity unit is an electricity enterprise granted a license to operate in the field of electricity transmission.”

2. Supplement Point d of Clause 1 of 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 operating generating unit in the national electricity system as determined by the System Operation Unit and Electricity Market.”

3. Amend and supplement Clause 1 of Article 38 as follows:

“1. Power plants with installed capacity over 30 MW must invest in equipment, control systems, AGC systems ensuring stable, reliable, and secure connection with the generating unit power control system of the System Operation Unit and Electricity Market to serve remote control of generating unit power according to dispatch orders from the System Operation Unit and Electricity Market. For power plants located in industrial zones that only sell part of their electricity output to the national electricity system, the necessity of equipping AGC systems is agreed upon and clearly stated in the Interconnection Agreement. Specific technical requirements for connecting AGC signals of generating units to the SCADA/EMS system of the System Operation Unit and Electricity Market are stipulated in the Technical Requirements and Management Regulations for the SCADA System issued by the Electricity Regulatory Authority.”

4. Supplement Clause 8 of Article 38 as follows:

“8. Generating units of power plants must maintain grid connection when the frequency deviation rate of the electricity system is within the range of 0 Hz/sec to 01 Hz/sec measured within a 500-microsecond time frame.”

5. Amend the name of Article 46 as follows:

“Article 46. Provision of Documents for Inspection of Connection Point Conditions for Testing and Acceptance”.

6. Amend and supplement the first bullet point of Point c of Clause 1 of Article 46 as follows:

“- Technical specifications of installed equipment including those of the interconnection lines;”

7. Amend the name of Article 47 as follows:

“Article 47. Inspection of Connection Point Conditions for Testing and Acceptance”.

8. Amend and supplement Clause 2 of Article 47 as follows:

“2. The transmission electricity unit has the responsibility to agree with customers requiring interconnection on the procedures for inspecting documents, acceptance records, and actual installation of equipment according to the Interconnection Agreement.”

9. Amend the name of Article 48 as follows:

“Article 48. Energizing the Connection Point for Testing and Acceptance”.

10. Amend and supplement Point a of Clause 1 of Article 48 as follows:

“a) Legal and technical documents of the project:

- Confirmation and commitment letters from customers requiring interconnection affirming that equipment within the energization scope has been tested and inspected to meet operational requirements, agreed-upon technical requirements at the interconnection point, and fully comply with legal regulations;

- Copies of inspection reports confirming that the connection point conditions have met all requirements specified in the Interconnection Agreement;

- Metering systems have been completed as required, with final readings of electricity meters settled;

- Power purchase contracts signed or agreements regarding power sales and delivery;”

11. Amend and supplement Clause 5 of Article 49 as follows:

“5. The grid, power plants, and electrical equipment after the customer's interconnection point can only be officially put into operation after having complete test, trial run, and acceptance records meeting all requirements stipulated in this Circular, planning, land, construction, fire prevention, environmental protection regulations, and other relevant legal provisions.”

12. Amend the name of Article 52 as follows:

“Article 52. Provision of documents for inspection of conditions for energizing connection points of transmission units' equipment for trial operation and acceptance”.

13. Amend Point d Clause 1 Article 52 as follows:

“d) A detailed diagram showing the connection plan of the power project of the transmission unit and parameters of the connection lines;”

14. Amend the name of Article 53 as follows:

“Article 53. Energizing connection points of transmission units' equipment for trial operation and acceptance”.

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

“a) Legal and technical documents:

- Documents confirming and committing by the Project Owner affirming that all equipment within the energization scope has been tested and inspected to meet operational requirements, technical requirements at the connection point, and fully comply with legal regulations;

- The metering system has been completed according to regulations, and the readings of electricity meters have been settled;”

16. Amend and supplement Clause 4 Article 59 as follows:

"4. The transmission system operates in an extremely emergency mode when one of the following conditions appears or persists:

a) The frequency of the power system falls outside the permissible frequency range in the case of a single fault occurring in the power system as stipulated in Article 4 of this Circular or after all reserve sources have been mobilized but the frequency continues to drop below 49.5Hz;
b) The load-carrying capacity of any device in the transmission grid or devices connected to the transmission grid exceeds 110% of its rated value, and if such a device fails due to overload, it may lead to partial collapse of the power system;

c) Voltage at any node on the transmission grid drops to a level causing low-voltage relay tripping of load shedding; voltage on the transmission grid is lower than 10% of the nominal voltage or there is a risk of system voltage collapse as calculated by the system dispatcher when no other measures can be taken except for load shedding and the voltage continues to trend downward.”

17. Supplement Point d Clause 3 Article 60 as follows:

“d) Requirements for the minimum configuration of power source mobilization and minimum inertia of the power system to ensure safe operation of the power system.”

18. Amend and supplement Clause 3 Article 62 as follows:

“3. Power generation units are responsible for operating power plants to maintain working voltage regulation and ensure sufficient reactive power supply to the power system during operation; they shall not disconnect generator sets from operation upon occurrence of faults, except in cases where the fault poses a threat to human life or equipment safety or the frequency exceeds the permissible limit as stipulated in Articles 38 and 42 of this Circular or is permitted by the System Operator and Electricity Market Operator.”

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

“a) Changing the power output of generator sets, stopping or starting generator sets to restore the power system to normal operating mode;

c) The automatic load shedding system must be arranged and set up reasonably to ensure that the power system does not collapse when a fault occurs. The System Operator and Electricity Market Operator are responsible for determining the installation locations and setting values of protective relays to perform load shedding in the event of a fault in the power system to ensure system security and stability;”

Amend and supplement some articles of Circular No. 39/2015/TT-BCT dated November 18, 2015, of the Minister of Industry and Trade on distribution systems

Article 3. 1. Amend and supplement Clause 1 Article 37 as follows:

"1. Power plants connected to the distribution network with a capacity of 10 MW or more or 110 kV substations must be equipped with information systems and connect these systems compatibly with the information systems of the Control Center with dispatching authority to serve communication and data transmission in power system operations. Minimum communication means for dispatching work include direct lines, telephones, DIM, and computer networks."

2. Supplement Point e Clause 2 Article 39 as follows:

"e. Generator sets of power plants must remain connected to the grid when the rate of change of system frequency is within the range of 0 Hz/sec to 01 Hz/sec measured over a time frame of 500 milliseconds."

3. Supplement Article 40a after Article 40 as follows:

3. Supplement Article 40a following Article 40 as follows:

“Article 40a. Requirements for solar and wind power sources connecting to medium voltage grid with capacity from 1 MW and below

1. At any time while connected to the grid, solar and wind power sources must be capable of maintaining continuous power generation for a minimum duration corresponding to the frequency bands specified in Table 5c as follows:

Table 5c.

Minimum Time to Maintain Operation to Generate Electricity

System Frequency Range

2. When the system frequency exceeds 50.5 Hz, solar and wind power sources must reduce their active power output according to the following formula:

Where:

- ΔP: The level of active power reduction (MW);

- P_{t s}: The active power output at the moment before the reduction (MW);

- f_{For power plants invested under the Build-Operate-Transfer (BOT) model, n is determined according to the operational period of the power plant stipulated in the BOT contract.}: The system frequency at the moment before the reduction (Hz).

3. Solar and wind power sources must be able to maintain continuous power generation within the voltage bands at the point of interconnection as specified in Table 5d as follows:

Table 5d.

Minimum duration of continuous power generation corresponding to the voltage bands at the point of interconnection

4. Solar and wind power sources shall not cause the direct current component to exceed 0.5% of the rated current at the point of interconnection when injected into the distribution grid.

5. Solar and wind power sources must comply with the regulations on voltage, phase balance, harmonic waves, voltage flicker, and grounding mode as stipulated in Articles 5, 6, 7, 8, and 10 of this Circular.

6. Solar and wind power sources must be equipped with protective devices ensuring the following requirements:

a) Automatically disconnect from the distribution grid in case of internal faults of the solar and wind power sources;

b) Automatically disconnect when a grid outage occurs and refrain from feeding power back into the grid during such outages;

c) Shall not reconnect to the grid automatically until the following conditions are met:

- The grid frequency remains within the range of 48Hz to 51Hz for a minimum of 60 seconds;

- All phases' voltages at the point of interconnection remain within the range of 85% to 110% of the rated voltage for a minimum of 60 seconds;

d) Customers requesting interconnection must agree and unify the protection system requirements with the Distribution Unit, but at a minimum, they must include the protections specified in points a, b, and c of this clause, overvoltage, undervoltage, and frequency-based protections.

7. In addition to the requirements stipulated in clauses 1 through 6 of this Article, solar and wind power sources with capacities ranging from 100 kW to 1 MW connecting to the medium voltage grid must also meet the following technical requirements:

a) Must ensure that the reactive power control mode is activated according to the power factor control mode with the power factor (cosphi) set according to the dispatching authority's requirements, except where there is a different agreement with the dispatching authority;

b) Must have the capability to establish a priority mode for active power or reactive power output as required by the dispatching authority when the voltage at the point of interconnection falls outside the continuous operation range specified in clause 3 of this Article.

8. The project owner of solar and wind power sources connecting to the medium voltage grid with capacities ranging from 100 kW to 1 MW is responsible for agreeing and unifying with the Distribution Unit regarding the equipment and means of connection to the dispatching system's data collection, monitoring, and control systems.

4. Supplement Point d of Clause 1 of 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 operating generating unit in the national electricity system as determined by the System Operation Unit and Electricity Market.”

5. Amend the name of Article 47 as follows:

“Article 47. Providing documents for inspecting conditions to energize connection points for trial operation and acceptance for customers using distribution networks connected at 110kV voltage level and customers with power generation units connected at medium voltage level.”.

6. Amend the name of Article 48 as follows:

“Article 48. Providing documents for inspecting conditions to energize connection points for trial operation and acceptance for customers with their own substations connected to medium voltage networks.”.

7. Amend the name of Article 49 as follows:

“Article 49. Inspecting conditions to energize connection points for trial operation and acceptance.”.

8. Amend and supplement Clause 3 of Article 49 as follows:

“3. The distribution unit shall be responsible for negotiating with customers who have connection requirements regarding the procedures for inspecting documents, acceptance records, and actual installation of equipment according to the Connection Agreement.”

9. Amend the name of Article 50 as follows:

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

10. Amend and supplement Point a of Clause 1 of Article 50 as follows:

“a) Legal and technical documents:

- A confirmation and commitment document from customers with connection requirements affirming that the equipment within the energization range has been tested and inspected to meet operational requirements, technical requirements at the connection point, and fully comply with relevant laws;

- Copies of inspection reports confirming that the connection point conditions have met all requirements specified in the Interconnection Agreement;

- The metering system has been completed, and the electricity meter readings have been settled.

- Power purchase contracts signed or agreements regarding power sales and delivery;”

11. Supplement Clause 4 of Article 50 as follows:

“4. For customers using electricity connected to medium voltage networks, energization of the connection point for trial operation and acceptance may be carried out immediately after the Inspection Record of Conditions for Energizing the Connection Point confirms compliance with all requirements stipulated in the Connection Agreement, fully meeting legal, technical, dispatching, operational requirements set forth in Clause 1 of this Article, and ensuring electrical safety.”

12. Amend and supplement Point d of Clause 1 of Article 51 as follows:

“d) The power grid, power plants, and electrical equipment after the customer's connection point can only be officially put into operation after having complete test reports, trial run reports, partial and full acceptance reports, fully meeting the requirements stipulated in this Circular, planning regulations, land regulations, construction regulations, fire prevention and firefighting regulations, environmental regulations, and other related laws.”

13. Amend the name of Article 55 as follows:

“Article 55. Providing documents for inspecting conditions to energize connection points of equipment of the Distribution Unit for trial operation and acceptance.”.

14. Amend the name of Article 56 as follows:

“Article 56. Energizing connection points of equipment of the Distribution Unit for trial operation and acceptance.”.

15. Amend and supplement Point a of Clause 1 of Article 56 as follows:

“a) Legal and technical documents:

- Documents confirming and committing by the Project Owner affirming that all equipment within the energization scope has been tested and inspected to meet operational requirements, technical requirements at the connection point, and fully comply with legal regulations;

- The metering system has been completed, and the electricity meter readings have been settled;"

16. Amend and supplement Clause 1 of Article 62 as follows:

“1. Managing and operating electrical equipment and power grids within the scope of management to ensure compliance with operational requirements and technical requirements stipulated in this Circular, adhering to the National Power System Dispatching Procedures, National Power System Operation Procedures, National Power System Incident Handling Procedures issued by the Ministry of Industry and Trade, and other relevant laws.”

17. Amend and supplement Point a of Clause 1 of Article 64 as follows:

“a) Managing and operating electrical equipment and power grids within the scope of management to ensure compliance with operational requirements and technical requirements stipulated in this Circular, adhering to the National Power System Dispatching Procedures, National Power System Operation Procedures, National Power System Incident Handling Procedures issued by the Ministry of Industry and Trade, and other relevant laws;"

18. Supplement Clause 2a after Clause 2 of Article 100 as follows:

“2a. Provincial Departments of Industry and Trade under the central government shall be responsible for inspecting and supervising compliance with the provisions of this Circular within their jurisdictional areas.”

Article 4. Implementation provisions

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

2. Repeal certain Articles and Clauses of Circular No. 25/2016/TT-BCT dated November 30, 2016, of the Minister of Industry and Trade on transmission systems, and Circular No. 39/2015/TT-BCT dated November 18, 2015, of the Minister of Industry and Trade on distribution systems as follows:

a) Repeal the second bullet point of Point a of Clause 3 of Article 92 and Clause 2 of Article 94 of Circular No. 25/2016/TT-BCT dated November 30, 2016, of the Minister of Industry and Trade on transmission systems;

b) Repeal Articles 92, 93, 94, 95, 96, 97, and 98 of Circular No. 39/2015/TT-BCT dated November 18, 2015, of the Minister of Industry and Trade on distribution systems.

3. In cases where electrical equipment has already been put into operation or there are procurement and installation contracts signed before the effective date of this Circular, if such equipment has different requirements or technical specifications compared to those stipulated in this Circular, relevant entities shall implement according to the relevant regulations prior to the effective date of this Circular.

4. During implementation, if any issues arise, relevant entities shall report them to the Electricity Regulatory Authority for examination and resolution within their authority, or report to the Ministry of Industry and Trade for resolution./.