Involuntary Load Shedding Explained

You many not be familiar with the term.  But if you are a Texan, you are familiar with its consequences. Load shedding is the practice of reducing demand or “load” on the electricity grid.   This is necessary when there is not enough supply in the system to meet the demand for electricity at a given time.  Maintaining a stable grid is a balancing act.  If the electricity being pumped into the grid and the electricity being pulled from the grid get too imbalanced, it can lead to cascading failures that can have long lasting consequences for the grid.

Voluntary Load Shedding and Demand Response

The are many types of voluntary load shedding.  This occurs when a public announcement is made asking customers to reduce their electricity usage within a certain area or a certain period of time.  Anyone who has lived in Texas through a particularly hot summer or cold winter is familiar with this process.

Demand response programs are another type of voluntary load sharing.   Large commercial users often participate in demand response programs.  Such programs will compensate customers for voluntarily reducing their electricity demands until supply and demand come back in line.  Manufactures and bitcoin miners are good candidates for demand response programs.

When there is not enough power to meet demand on the grid, ERCOT looks to bring additional power production online.  If this isn’t enough, they will ask for voluntary reduction in power from the public.  As a last resort, they will institute involuntary load shedding procedures.

Involuntary Load Shedding Procedures

When involuntary load shedding occurs, ERCOT will contact Distribution Service Providers (DSP) and tell them to immediately begin shedding load to reduce strain on the grid.   DSPs include the TDU’s such as ONCOR and CenterPoint.  They also include municipal electric companies and co-ops such as Denton Municipal Electric and South Texas Electric Cooperative.

The DSP are told to reduce their load in proportion to their total typical percentage of system wide demand.  For example, CenterPoint is asked to contribute 24.78% of the total load shed while Lamar County Electric Cooperative is asked to contribute just .07% of the load shed.

It is up to the DSPs to determine how they implement the load shedding and who they cut power off to.  They will give priority to customers designated as critical load.  This includes hospitals and emergency services such as 911.  However, there is no guarantee that critical load customers will not also lose power.

Operators try to reduce the impact on any give customer or area by implementing rolling blackouts to whatever extent possible.   During involuntary load shedding events customers should expect to lose power periodically without warning.  The rolling blackouts will continue until the grid emergency has passed.  This could be a mater of minutes, hours, or, in extreme cases, even days.