LSS Technical Functionality

Understanding the Grid

The electricity grid is fed with alternating current, which has a frequency of approximately 50.0 Hz. The grid frequency is the same all over the grid, with the exception of local short-term swings.

At every moment the amount of electricity that is generated by the power plants must be equal to the amount of energy that is taken from the grid by the consumers. If the power demand increases beyond the power supplied by the generators, then the power deficit between supplied and removed power is reflected in the rotational speed of the generators which turn slower, which means the grid frequency decreases.

The drop in line frequency is an indication that the increased load is causing the generators to slow down.

Various staggered control mechanisms provide the adjustment of the output of the generators to regain the 50.0 Hz when a deviation from the desired frequency occurs. In normal network operation there are regular deviations up to 0,150 Hz, the primary control power is fully used at a deviation of 0.200 Hz.

Necessity for Load-Shedding

When electrical consumption of large consumers get on/off grid unexpectedly, then deviations from 800 mHz (49,200 Hz to 50.800 Hz) are allowed for a short period.

A massive failure in the network is very likely at deviations greater than 800mHz. In this case an immediate plan for load-shedding comes into force to avoid problematic network conditions which can be catastrophic!

In essence, Load-Shedding is necessary to avoid a complete melt-down of the power grid!

LSS Operation

When a sustained drop in the frequency is detected, all LSS Systems commence with level 1 cycle limiting operation. The system is programmed to operate with multiple levels of cycle limiting, ranging from a 10% limitation to a 90%.

In the event of the grid frequency remaining below the threshold after the activation of the cycle limiting, the system moves progressively through the levels until such time as the grid frequency attains normal operating parameters.

When the frequency rises above the threshold whilst the system is cycle limiting, a progressive reduction in the cycle limiting level is implemented. The reduction of the cycle limiting level, progressing to a 100% removal of all cycle limiting is accomplished by groups of systems switching on progressively in a controlled sequence thereby eliminating the problem of excessive strain being placed on the grid should all systems switch on simultaneously.