AG10 battery.Technical requirements of power grid companies for inverters to be connected to distribution grids

　　Distributed power supplies of 10 kV and below are divided into two categories: inverters and rotating motors according to the form of connection to the power grid. Inverter-type distributed power supplies are connected to the grid through inverters, mainly including photovoltaic, full-power inverter grid-connected wind turbines, etc.

　　Technical requirements for inverter-type distributed power supply to be connected to 10 kV distribution network

　　1. The grid connection point should be equipped with a breaking device that is easy to operate, can be blocked, has obvious breaking points, has a grounding function, and can break fault current.

　　2. The inverter should comply with relevant national and industry technical standards, and have the functions of high/low voltage blocking and automatic grid connection when voltage is detected (see Table 1 for voltage protection action time requirements; automatic grid connection when voltage is detected at 85%UN).

　　Table 1: Voltage protection action time requirements

　　3. When the distributed power supply is connected through a dedicated line, the dedicated line does not need to be equipped or the reclosing switch is disabled.

　　4. When the public power grid line is put into automatic reclosing, the reclosing function of detecting no voltage should be added; if the conditions are not met, it should be checked whether the reclosing time cooperates with the distributed power grid connection and off-grid control time (the reclosing time should be set to 2+ δt seconds, δt is the protection cooperation step difference time).

　　5. The power factor of distributed power supply should be adjustable within the range of 0.95 (lead) ~ 0.95 (lag).

　　Technical requirements for inverter type distributed power supply connected to 220/380 volt distribution network

　　1. The grid-connected point should be installed with a low-voltage grid-connected special switch that is easy to operate, has obvious breaking indication, and has the ability to break fault current. The special switch should have the functions of loss-of-voltage tripping and voltage-detection closing. The setting value of the loss-of-voltage tripping should be adjusted It is 20%UN and 10 seconds. The pressure check value should be set to greater than 85%UN.

　　2. The inverter should comply with relevant national and industry technical standards, and have the functions of high/low voltage blocking and automatic grid connection when voltage is detected (see Table 1 for voltage protection action time, automatic grid connection at 85%UN when voltage is detected).

　　3. When the distributed power access capacity exceeds 25% of the rated capacity of the distribution transformer in the station area, the low-voltage side knife fusion main switch of the distribution transformer should be transformed into a low-voltage main switch, and an anti-islanding device should be installed at the low-voltage busbar of the distribution transformer; the low-voltage main switch The switch should have an operation blocking function with the anti-islanding device. When there is contact between the busbars, the contact switch should also have an operation blocking function with the anti-islanding device.

　　4. When the distributed power supply is connected to the 380-volt distribution network, a three-phase inverter should be used; before the distributed power supply is connected to the 220-volt distribution network, the total single-phase connection capacity of the same station should be checked to prevent three-phase Power imbalance condition.

　　5. The power factor of distributed power supply should be adjustable within the range of 0.95 (lead) ~ 0.95 (lag).

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