1Power quality monitoringEquipment requirements
1) The power quality testing conducted in accordance with GB/T 29319-2012 "Technical Regulations for Connecting Photovoltaic Power Generation Systems to Distribution Networks" includes voltage transformers, current transformers, and data acquisition devices. The accuracy of measurement equipment requires that the channel bandwidth of the data acquisition device should not be less than 10MHz.
The power quality measurement device should comply with GB/T17626 The flicker algorithm of the measuring device should comply with GB/T 17626 according to the requirement of 30 15.
2) For the power quality testing conducted in accordance with Q/GDW 617 "Technical Regulations for Connecting Photovoltaic Power Stations to the Grid" and Q/GDW 618 "Testing Regulations for Connecting Photovoltaic Power Stations to the Grid", the power quality testing device should meet the technical requirements of GB 19862 and DL/T1028, and meet the measurement accuracy requirements of IEC 61000-4-30 Class A.

2. Steps for monitoring power quality
(1) Grid conditions.
When the photovoltaic power generation system stops operating, the relevant technical indicators at the grid connection point should meet the following requirements:
1) The root mean square value of the total distortion rate of voltage harmonics measured within 10 minutes should meet the provisions of GB/T 14549;
2) The deviation of the average measurement value of the 10s grid frequency should meet the provisions of GB/T 15945;
3) The deviation of the root mean square value of the grid voltage for 10 minutes should meet the provisions of GB/T 12325;
4) The three-phase imbalance of power grid voltage should meet the provisions of GB/T 15543.
(2) Detection of three-phase imbalance.
1) The steps for detecting three-phase voltage imbalance are as follows:
a) Connect the power quality measurement device at the public connection point of the photovoltaic power generation system;
b) Run the photovoltaic power generation system, starting from the low power that the photovoltaic power generation system continues to operate normally, with 10% of the total rated power of the inverter installed in the photovoltaic power station as a range, and continuously measure for 10 minutes in each range. Starting from the range, calculate the root mean square value every 3 seconds, and calculate a total of 200 3 seconds of root mean square root;
c) Record the 95% probability maximum of the measured weight value of the negative sequence voltage imbalance, as well as the values from all measured values;
d) Repeat the measurement once.
Note: The endpoint of a range measures the continuous normal operation power of the solar photovoltaic power generation system.
2) Detection of three-phase current imbalance.
It is advisable to simultaneously measure the sub phase current imbalance, and the method should refer to three-phase voltage imbalance detection.
(3) Flashing.
Connect the power quality measurement device at the public connection point of the photovoltaic power generation system, and the cut-off frequency for measuring voltage and current should not be less than 400Hz. Starting from the continuous and normal operation of the photovoltaic power generation system at low power, 10% of the total rated power of the inverter in the photovoltaic power generation system is used as a range, and the 10 minute short-term flicker value Psto is measured twice in each range. The long-term flicker value of the photovoltaic power generation system should be calculated through the short-term flicker value Pst, and the detection method should meet the requirements of GB/T 12326.
Note: The endpoint of the interval measures the continuous normal operation power of the solar photovoltaic power generation system.
(4) Harmonics, inter harmonics.