Chapter 3.
POWER METERING POSITION AND TECHNICAL REQUIREMENTS FOR POWER METERING SYSTEM
SECTION 1. SETTING POWER METERING POINT AND POWER METERING SYSTEM
Article 11. Power metering point
1. Identification principle
a) The metering point identified must be identical or adjacent to the connection point;
b) Where it is ineligible for arranging the metering system as stipulated at Point a, Clause 1 of this Article, the generating organization and the power trading organization shall negotiate about the alternative power metering point and determine the mode of power conversion from the alternative metering point to the connection point.
In case the alternative power metering point is placed at the power station of the power grid managing organization, the generating organization shall negotiate and reach an agreement with the power trading company and the power grid managing organization on the metering point and negotiate with the power trading company about the mode of power conversion from the alternative metering point to the connection point.
c) Where the metering point does not ensure the correct metering of trading power, the power generating organization and the power trading company must reach an agreement on the mode of calculation of power converted to the connection point.
2. Specific case
a) Connection point of the power plant
- The main metering point is identified at the main circuit breaker or terminals of the high, medium voltage of the booster transformer and high voltage of backup auxiliary transformer to receive power from the connection point, unless otherwise agreed.
- Backup 1 metering point is identified at the outgoing feeder of the power plant, unless otherwise agreed.
- Backup 2 metering point is identified under the agreement between the power generating organization and the power trading company;
b) The connection point does not belong to the power plant
- Where the power plant has a line in contact with the connection point and no power bypassing the busbar of the power plant, the main and backup 1 metering point is identical or adjacent to the connection point.
- The backup 2 metering point is identified under the agreement between the power generating organization and the power trading organization;
- Where the power plant has 02 or more lines with power bypassing the busbar of the power plant, the metering point is selected in accordance with provision at Point a, Clause 2 of this Article.
Article 12. Power metering system
1. At each metering point, there must be a main metering system and 02 backup metering systems (backup 1 and 2).
2. The main metering system must identify the metering quantities of power trading as a main basis for power billing through the connection point and elimination of elements affecting the metering result by the loop structure of electrical system.
3. The backup metering system has the following functions:
a) Replacing the main metering system as basis for calculating quantities of power trading in case the main metering system operates inaccurately or has breakdowns
b) Monitoring and checking the metering result of the main metering system in the normal working condition of the main metering system;
c) Combining the main metering system and other backup metering systems to calculate the power production for calculation in some special cases.
SECTION 2. TECHNICAL REQUIREMENTS FOR THE POWER METERING AND DATA TRANSMISSION SYSTEM
Article 13. Minimum configuration of power metering system
The minimum configuration of power metering system includes:
1. Current transformer.
2. Voltage transformer.
3. Power meter
4. Electrical circuit and the secondary cable
5. Devices for gathering of metering data and data transmission.
6. Safety devices, seal location and lead seal.
7. Auxiliary devices, connection switching devices, metering circuit isolator for testing, logic devices for voltage transformer and devices of voltage and current
Article 14. Technical requirements of power meter
1. General requirements
a) 3-phase 4-wire type;
b) Function-integrated electronic and programmed type;
c) With many tariffs;
d) Metering of active and reactive power by separate two ways of receiving and sending into 4 quadrants;
dd) With function of metering of maximum capacity and recording of total loading chart;
e) With function of connection to computer, gathering and reading data on the spot and from a distance;
g) Being powered from the secondary voltage metering system with required maintenance of operation upon loss of 1 or 2 phase voltage.
h) With levels of password;
i) With places of seal and lead seal to ensure impossible access to the wiring terminals and change of parameters set up in the meter without removing the lead seal;
k) With function of storing the metering information and loading chart at least 60 days with the cycle of recording the metering value not exceeding 30 minutes.
2. Requirements for accuracy level
a) The main meter must satisfy the accuracy level 0.2 with active power by standard IEC 62053-22 and 2.0 with reactive power by standard IEC 62053-23 or other equivalent standards.
b) The backup meter must satisfy the accuracy level 0.5 with the active power by standard IEC 62053-22 and 2.0 with reactive power by standard IEC 62053-23 or other equivalent standards.
Article 15. Technical requirements of current transformer for power metering
1. General requirements
a) Having a secondary winding used separately for metering devices and power meter.
b) Value of nominal secondary current is 1A or 5A;
c) Having the place of lead seal at the lid of junction box of secondary winding connecting the metering devices and power meter to ensure no impact on the connected circuit without removing the seal.
2. Requirements for accuracy level
a) The current transformer for main metering must satisfy the accuracy level 0.2 with active power by standard IEC 60044-1 or other equivalent standards.
b) The current transformer for backup metering must satisfy the accuracy level 0.5 with active power by standard IEC 60044-1 or other equivalent standards.
Article 16. Technical requirements of voltage transformer used for power metering
1. General requirements
a) Having a secondary winding used separately for metering devices and power meter.
b) Value of nominal secondary current is 100V or 110V;
c) Having a place of lead seal at the lid of junction box of secondary winding connecting the metering devices and power meter to ensure no impact on the connected circuit without removing the seal.
2. Requirements for accuracy level
a) Voltage transformer for the purpose of main metering must satisfy the accuracy level 0.2 by the standard IEC 60044-2 for inductive voltage transformer and standard IEC 60044-5 for capacitive voltage transformer or other equivalent standards.
b) Voltage transformer for the purpose of backup metering must satisfy the accuracy level 0.5 by the standard IEC 60044-2 for inductive voltage transformer and standard IEC 60044-5 for capacitive voltage transformer or other equivalent standards.
Article 17. Technical requirements of metering circuit
1. The secondary winding of CT, VT and secondary cable connected to the power meter of the main metering system must not be used for any purpose and must be independent from the backup metering system.
2. The secondary cable of the metering circuit must be wired by the shortest way and a number of connection points through circuit connector is the least and sealed on the circuit connector cabinet or connection point. The secondary cable of the main metering system must be wired separately and directly connected from the junction box of CT, the intermediate cabinet of VT to the meter box without going through the circuit connector at the intermediate box.
3. Where the meter is supplied with voltage from one of VT busbar through the voltage circuit transformer, the wiring terminals of voltage switch must ensure the condition of seal and lead seal and the power meter must be programmed to record the time and duration of the voltage switching.
4. The loading of secondary circuit of CT and VT including the power meter must not exceed the rated loading of CT and VT.
5. Where the current circuit of the backup metering system is used in conjunction with other metering devices, it is required to affect the accuracy of the metering system and be eligible for sealing with lead all current circuit, metering devices and power meter.
6. The trial junction boxes must be installed for the testing of metering devices and eligible for seal and lead seal.
Article 18. Technical requirements for the system of gathering and processing of metering data
1. The power meters must be connected with the remote data reading system in accordance with the connection standard and data gathering software of the metering data managing organization.
2. The portal and integrated communication equipment and modem in the meter must fit the connection standard of the metering data managing organization and allow the remote connection with the meter from the computer in place and from the center for gathering, processing and storing the metering data of the metering data managing organization.
3. The format of data file and connection interface standard supplied by the metering data managing organization depends on the model of information gathering and the mode of metering data transmission.
4. The data gathering system must include the computed in place and the host computer placed at the metering data managing organization. The metering data gathered from the computer in place must be transmitted to the database of the host computer.
5. The transmission environment of usable information is the wired or wireless system to ensure the compatibility with the devices of gathering, processing and storing of power metering data placed at the center for gathering, processing and storing of power metering data of the metering data managing organization. The environment and mode of information transmission must be secured to prevent unauthorized intrusion.
6. The information equipment connecting with the power meter must be installed with the appropriate lightning protection devices to prevent the effect of lightning impulse propagating through the information network causing damage to the meter.
7. The devices installed in panel cabinet must fit the safety and convenience requirements for the management work.
8. System of data transmission and format of data file and connection interface standards of the metering system must comply with the Regulation on technical standard of the system of data transmission developed by the metering data managing organization specified in Article 32 of this Circular.
Article 19. Functional requirements for the system of gathering and processing of metering data at the metering points
The system of gathering and processing of metering data at the metering points must have the following functions:
1. The gathering of metering data of meters is under the scope of the metering system operation managing organization is permitted for the implementation in 02 forms as follows:
a) Daily automation at predetermined time;
b) Manual performance upon requirement.
2. The metering data transmission to the metering data managing organization is done in the 02 forms as follows:
a) Automatic transmission to the metering data managing organization after completion of process of data reading of power meter;
b) Manual performance upon requirement
3. Management of metering data:
a) Storing the metering data in the computer in place after the reading from the meter;
b) Automatically adjusting the metering data by the mode of calculation of converted metering data as agreed between the power generating organization and the power trading organization. The metering data managing organization shall set up the program of calculation of converted metering data for the computers in place and have the encoding measures to prevent unauthorized change;
c) Storing the adjusted data.
4. Managing time, reading schedule and data gathering.
5. Managing the access including the code and user’s access right to the system.
6. Managing the metering information:
a) Managing list of metering devices;
b) Managing the declaration of information of metering points and metering system;
c) Managing the technical information of devices and metering system.
Article 20. Functional requirements for the system of gathering and processing of metering data of the metering data managing organization
The system of gathering and processing of metering data of the metering data managing organization must have the following functions:
1. Gathering the metering data from the metering points for the metering data managing organization through the computer in place of the metering system operation managing organization.
2. Gathering the metering data through the connection of direct data reading between the meter data reading program of the metering data managing organization to the meter within the scope of the metering system operation managing organization.
3. The gathering of metering data permits the implementation in two forms:
a) Daily automation at predetermined time;
b) Manual performance upon requirement.
4. Time synchronization with standard time source for all the meters in the system
5. Management of metering data:
a) Storing of data after reading from the meter;
b) Checking, comparison, adjustment and addition of metering data;
c) Storing of adjusted data.
6. Management of time, reading schedule and data gathering.
7. Management of access including code and user’s access right to system.
8. Management of metering data:
a) Management of information and metering list of generating organization;
b) Management of declaration of information, metering point and metering system;
c) Management of technical information of devices and metering system.
9. Connection and share of data with software program of the electricity system and market operating organization.
Article 21. Technical requirements for seal and lead seal and security
1. The entire system of power metering includes CT and VT junction box, power meter, circuit connector, connector, current circuit, voltage circuit, auxiliary devices, converted logic circuit, meter cabinet and information network must be sealed or sealed with lead to prevent unauthorized intervention.
2. The software of power meter must have protection password with different access permissions.
3. The metering data after being read and transmitted to the server placed at the metering point must be encoded to prevent unauthorized change before being transmitted to the metering data managing organization.
4. The system management software of reading, transmission and integration of power metering must be secured by many password levels to ensure the security, accuracy and reliability of metering data.
Tìm kiếm
Thông tư 27/2009/TT-BCT quy định đo đếm điện năng trong thị trường phát điện cạnh tranh do Bộ Công thương ban hành (Bản Word)