Technical Regulations of State Grid on grid-connection of small household photovoltaic power generation system

1. Preface

In order to promote the scientific and orderly development of photovoltaic power generation for small households and standardize the technical indicators for connecting the photovoltaic power generation for small households to the grid, the Development Planning Department of State Grid Corporation has organized the China Electric Power Research Institute to compile the Technical Regulations for Connecting the Photovoltaic Power Generation System for Small Households to the Grid. Based on the grid structure and grid operation requirements for small household photovoltaic power generation in our country, combining the characteristics of small household photovoltaic power generation, this standard conducts a thorough study on the influence of small household photovoltaic power generation on grid, and fully absorbs the relevant technical regulations and standards for grid connection of distributed power set up by International electricity Association and power companies. This standard refers to or refers to existing national standards, industry standards, IEC standards and IEEE standards in terms of power quality, safety and protection and general technical conditions, and combines with the special requirements for grid connection and operation of small household photovoltaic power generation to establish technical indicators suitable for connecting small household photovoltaic power generation to the grid.

2. Scope

This standard specifies the technical requirements to be followed for the operation of household photovoltaic power generation systems connected to the grid. This standard is applicable to new, expanded or reconstructed grid-connected photovoltaic power generation systems with 220V single-phase access and installed capacity not exceeding 8kWp, including connection modes with and without isolation transformers. Not applicable to off-grid photovoltaic power generation systems. The photovoltaic power generation system with three-phase access shall be implemented in accordance with Q/GDW617 Technical Regulations for Photovoltaic Power Station Access to the Power Grid.

3 Terms and Definitions

3.1 residential photovoltaic (PV)power system

It refers to a power generation system that uses the photovoltaic effect of solar cells to convert solar radiation energy directly into electric energy and connects it to the user-side grid at 220V single-phase.

3.2 point of interconnection(POI)

Output summary point of household photovoltaic power generation system.

3.3 islanding

A state in which the part of the grid containing load and power continues to operate in isolation from the main network. Islands can be divided into unplanned islands and planned islands.

Note: Unplanned island refers to an unplanned and uncontrolled island. Planned island refers to the occurrence of planned islands according to pre-configured control policies.

3.4 anti-islanding

Prevent the occurrence of unplanned island phenomenon.

3.5 Peak wattspeak(Wp)

The output power of the maximum power point of a photovoltaic module or photovoltaic array under standard test conditions.

4 Power Quality

4.1 Harmonics and interharmonics

After the household photovoltaic power generation system is connected to the power grid, the sub-harmonics and inter-harmonics of the connecting point should meet the requirements of GB/T14549 and GB/T24337.

4.2 Voltage Deviation

After the household photovoltaic power generation system is connected to the power grid, the voltage deviation of the connecting point should meet the requirements of GB/T12325.

4.3 Voltage fluctuation and flicker

After the household photovoltaic power generation system is connected to the power grid, the voltage fluctuation and flicker of the connecting point shall meet the requirements of GB/T12326.

4.4 DC component

The DC current injected into a residential PV system should not exceed 0.5% of its AC current rating.

4.5 Three-phase voltage unbalance

The three-phase voltage unbalance of the 380V system caused by the access of the household photovoltaic power generation system should meet the requirements of GB/T15543.

5 Security and Protection

5.1 Basic Requirements

The household photovoltaic power generation system should be set in the connecting point of easy to operate, with obvious break point, can be broken fault current switching equipment.

5.2 Anti-island Protection

The household photovoltaic power generation system should have the ability to quickly monitor the island and disconnect from the power grid immediately, and the anti-island protection action time should not be more than 2s.

5.3 Residual current protection

The household photovoltaic power generation system shall install the residual current protection device at the connecting point, and shall meet the relevant requirements of GB13955 and GB50054.

5.4 Voltage and frequency protection

6. What are the components of a grid-connected photovoltaic power generation system?

1. Photovoltaic array (fixed or tracked);

2. Junction box;

3. Dc power distribution cabinet;

4. Grid-connected inverter;

5. Ac power distribution cabinet;

6. Power grid access system (booster voltage, metering equipment, etc.);

7. Ac/DC cable;

8. Monitoring and communication devices;

9. Lightning protection grounding device.

The photovoltaic array converts solar energy into direct current (DC) electric energy. After DC and AC inverter inverter, the voltage level of the photovoltaic power station connecting to the grid is determined according to the capacity of the photovoltaic power station connecting to the grid. After the transformer boosting voltage, the photovoltaic power station is connected to the medium-voltage or high-voltage grid.

Solar panels are the core part of the solar power system, the role of solar panels is to convert the sun's light energy into electric energy, output direct current stored in the battery. Solar panel is one of the most important components of grid-connected photovoltaic power generation system. Its conversion rate and service life determine whether the component has useful value.