Dynamic Controlled Demand responding to system frequency deviation for synthetic inertia support

National Grid has a statutory obligation to keep the frequency within a fixed range of 49.2Hz to 50.4Hz. This range may not be exceeded for a significant event (loss of demand up to 1000MW) or an abnormal event (loss of generation up to 1320MW). National Grid must therefore know what system inertia is instantly available and what extra generation must be held in standby. If this is wrong then the consequences can be expensive.

Over the years the system has been changing; on the generation side, much high inertia coal fired power stations have closed down and there has been an increase of wind farms and embedded generation. On the demand side, heavy industry with direct on-line machines in pumps, fans and compressors has reduced with declining manufacturing and the introduction of power electronics. Additional complexity in the future could be added by the introduction of synthetic inertia.

This project looks to determine if demand side management can damp the frequency on the grid by reacting to changes in frequency with small changes in power in fast time scales using power electronics. The aim is to determine what loads have a voltage/ power relationship and use this to chop the voltage to a lower value to reduce power when the frequency is low and vice versa when the frequency is high. The power electronics would aim to be low cost devices located at a plug socket (eventually the plug) and supplied with the load. The customer would see no impact on their load as all voltages would be adjusted within voltage statutory levels. This is designed to be a feasibility study to establish the potential.