ABB PML630 Load Shedding Controller

ABB PML630 Load Shedding Controller

The IED supports various modes of load shedding.

Core functions

Ensuring power supply for critical loads: In the event of network interference, PML630 can quickly, accurately, and selectively cut off non critical loads to ensure continuous power supply for critical process loads. This function greatly reduces the duration and frequency of industrial production interruptions in the distribution network, while avoiding damage to electrical and process equipment due to power outages.

Based on comprehensive power and low-frequency load shedding: This controller integrates comprehensive power and low-frequency load shedding mechanisms. In the face of emergency situations such as loss of single or multiple power sources, grid disintegration, network or process conditions (such as frequency change rate, etc.), the ability to quickly respond to load shedding ensures the stability of the power system.

Working mode

Fast load shedding: When a serious imbalance in the power system is detected due to network emergencies (such as short circuit faults, line trips, etc.), PML630 can perform a fast load shedding operation in a very short period of time (from interference detection to unloading command generation time guaranteed within 20 milliseconds), quickly cutting off some less important loads, preventing a significant decrease in system frequency and voltage, and maintaining stable system operation.

Slow load shedding: PML630 will activate the slow load shedding mode based on situations such as transformer overload or violations of the maximum demand of power grid interconnection lines and generators. By gradually cutting off the load, the power system can be restored to a safe operating state, avoiding damage to equipment caused by long-term overload.

Manual load shedding: Operators can manually initiate unloading operations based on power definitions or load feeder priorities. This flexible control method allows for human intervention in power distribution in specific situations, such as planned maintenance, system debugging, etc., to ensure that system operation meets actual needs.

Low frequency load shedding (backup): As a backup mechanism for fast and slow load shedding, low frequency load shedding plays a role when the system frequency continues to decrease and other load shedding measures fail to effectively prevent it. When the system frequency is below the preset threshold, PML630 will cut off some loads in the predetermined order and magnitude to prevent system frequency collapse.

Safety information Dangerous voltages can occur on the connectors, even though the auxiliary voltage has been disconnected. Non-observance can result in death, personal injury or substantial property damage. 

Only a competent electrician is allowed to carry out the electrical installation. National and local electrical safety regulations must always be followed. 

The frame of the IED has to be carefully earthed. Whenever changes are made in the IED, measures should be taken to avoid inadvertent tripping. 

The IED contains components which are sensitive to electrostatic discharge. Unnecessary touching of electronic components must therefore be avoided.

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