Why we should us anti-island protection relay?

1. Introduction

Island effect: When the power supply of the power grid is interrupted due to faults, misoperation or power outage maintenance, each new energy grid-connected power generation system is still running and supplying power to the surrounding loads, forming a self-sufficient power supply island that the power company cannot control.

When the island effect occurs, the hazards caused are:

1) The power grid cannot control the voltage and frequency in the island. If the voltage and frequency exceed the allowable range, it may cause damage to the user's equipment;

2) If the load capacity is greater than the inverter capacity, the power supply is overloaded and easily burned;

3) Reclosing the island will cause the line to trip again, which may damage the inverter or other equipment;

4) The line connected to the inverter is still energized, which will cause harm to maintenance personnel and reduce the safety of the power grid.

2. Acrel AM5SE-IS Anti-Island Protection Relay

Ankerui AM5SE-IS anti-island protection device is mainly suitable for 35kV, 10kV and low voltage 380V photovoltaic power generation, gas power generation and other new energy grid-connected power supply systems. When an islanding phenomenon occurs, the grid connection point can be quickly cut off to quickly disconnect the station from the grid side, ensuring the safety of the entire power station and related maintenance personnel.

3. Functions

3.1 Protection Functions

● Three-stage over-current protection (can be locked by low voltage, can be locked with direction)

● Inverse time over-current protection (can be locked by low voltage)

● Two-stage zero sequence I01 over-current (can be locked with direction)/I01 inverse time over-current protection

● Two-stage zero sequence I02 over-current (can be locked with direction)/I02 inverse time over-current protection

● Low voltage trip

● Low voltage alarm

● Over-voltage protection (trip/alarm)

● Zero sequence over-voltage protection (trip/alarm)

● Reverse power protection

● Frequency protection (low frequency load reduction/high frequency protection)

● Frequency mutation trip

● Automatic closing with pressure

● Re-closing

● Post-acceleration over-current protection (can be locked by low voltage)

● Overload alarm

● Overload trip

● PT disconnection alarm

● Control circuit disconnection alarm

● Over-current lock function coordinated with FC circuit

● Non-electrical protection (tripping/alarm)

● Synchronization check

● CT disconnection alarm

● Maintenance status lockout

3.2 Monitor Functions

● Independent operation circuit, can adapt to 0.25A-5A switch tripping and closing current

● 20 active switch inputs

● 10 passive relay outputs

● I, U, P, Q, PF, Fr, Ep, Eq and other electrical parameter measurements

● 2 4-20mA transmission outputs

3.3 Communication Functions

● 2-way RS485 serial communication interface, supporting Modbus-RTU and IEC60870-5-103 protocols

● 2-way Ethernet interface, supporting TCP Modbus-RTU and TCP IEC60870-5-103 protocols

3.4 Other Functions

● Fault recording function, triggering recording when protection action occurs, can record 8 cycles before the fault and 4 cycles after the fault

● IRIG-B format timing