System Requirements

• System isolation requirement: The PID module must be used for system isolation. The AC and DC sides of the inverter are not grounded. Therefore, when the PID module is applied to a low-voltage power grid, an isolation transformer must be used for isolation.
• Application scenario requirement: If a double-column transformer is used, select the smart array controller with one PID module. If a dual-split transformer is used, select the smart array controller with two PID modules.
• PV array requirement: When the PID module is used in a PV array that comprises SUN2000s (in the scenario with a double-column transformer, the DC capacity of the PV array should be less than or equal to 10 MW; in the scenario with a dual-split transformer, the DC capacity of the PV array should be less than or equal to 16 MW), the PV modules in the array must be of the same type.
• Functional earthing requirement: The PID module functional earthing cable should connect to the ground bar on the low-voltage side of the box-type transformer and be grounded reliably.
• AC power cable requirement 1:
  The AC power cables refer to those from the SUN2000 to the AC combiner box, from the AC combiner box to the box-type transformer, from the box-type transformer to the smart array controller, inside the AC combiner box, inside the box-type transformer, and directly or indirectly from the box-type transformer to the busbar on the low-voltage side of the box-type transformer.

  • When the rated three-phase AC input voltage of the smart array controller is 800 V, ensure that the rated operating voltage of the AC power cable to ground is greater than or equal to 1000 V AC.
  • When the rated three-phase AC input voltage of the smart array controller is 500 V, ensure that the rated operating voltage of the AC power cable to ground is greater than or equal to 600 V AC.
• AC power cable requirement 2: The AC power cable from the low-voltage side of the box-type transformer to the smart array controller is at least 3 meters, and a four-core outdoor armored cable with a cross-sectional area of 10 mm² is recommended.
• AC power cable connection requirement: The PID module must be applied to a three-phase, three-wire system. If the neutral wire is connected, there is a risk of high voltage. Therefore, the neutral wire must not connect to the SUN2000, AC combiner box, or AC power distribution cabinet. If the low-voltage side of the isolation transformer uses star connection, the neutral wire must not be connected or grounded, and isolation protection measures should be taken.
• Requirements for the SPD on the AC combiner box and that on the low-voltage side of the box-type transformer:
  • When the rated three-phase AC input voltage of the smart array controller is 800 V, SPDs are connected in 3+1 mode. All SPD modules use piezo-resistors and no gas discharge tube is allowed. The maximum continuous operating voltage (Uc) of each SPD module should be greater than or equal to 680 V AC.
  • When the rated three-phase AC input voltage of the smart array controller is 500 V, SPDs are connected in 3+1 mode. All SPD modules use piezo-resistors and no gas discharge tube is allowed. The maximum continuous operating voltage (Uc) of each SPD module should be greater than or equal to 385 V AC.
• Knife fuse switch requirements: In the scenario with a double-column transformer, one knife fuse switch should be reserved for the busbar on the low-voltage side of the box-type transformer. In the scenario with a dual-split transformer, one knife fuse switch should be reserved for each low-voltage winding main busbar on the low-voltage side of the box-type transformer. This power branch connects to the smart array controller and delivers input voltage to it. This power branch must directly connect to the busbar on the low-voltage side of the box-type transformer, and must not connect to the isolation transformer embedded in the box-type transformer.

System Networking

Figure 2-7 shows the cable connections for the smart array controller in which the PID module is used.

• If a double-column transformer is used, select the smart array controller with one PID module.
• If a dual-split transformer is used, select the smart array controller with two PID modules.

NOTE:

For details about the working principle of the smart array controller, see the SmartACU2000B Smart Array Controller User Manual (with PID Modules, 800 V AC).

Figure 2-7 Cable connections

NOTE:

• Components in dashed-line boxes are optional.
• In the box-type transformer, the knife fuse switch serves as the three-phase power switch.