Black-Start Units Play Critical Role in North American Power Industry

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Researched by Industrial Info Resources (Sugar Land, Texas)--Black-start electrical resources are a critical component during a major system-wide blackout or the collapse of an electrical grid. These resources ensure that emergency services, as well as utility customers' electricity, can be restored. Every region in the North American Electric Reliability Corporation (NERC) has its own black-start plan and procedures, as well as designated units capable of generating power and restarting the system.

A black-start generator must be capable of restarting after a system-wide blackout, without help from an offsite electrical supply. The unit must have one or more diesel-fired generators or combustion-turbine generators, or a combination of both, which is required by all electrical power market and balancing authorities in case of an electrical blackout.

The controls used by a black-start generator include a direct current (DC) auxiliary support system, an ignition source, and the internal combustion diesel generator or gas turbine generator. Newer black-start technology allows for automatic dual-mode switching between grid-connected mode and stand-alone mode, which may be needed during rolling blackouts, severe weather or other conditions. The DC auxiliary battery system must have enough capacity to provide a generator with multiple start attempts in case of failure to fire on the first try.

The loss of grid-connected alternating current (AC) also causes an undercurrent relay to initiate the DC system in order to provide power to auxiliary systems, such as the turbine lube oil pump, liquid fuel-forwarding pump, lighting, air compressor, starting clutch, diesel-starting motor, turning gears, igniter spark plugs and circuit breakers.

Some black-start generators have never been used during an actual black-start condition, but all must undergo annual testing to ensure a fast response from their instruments and controls systems in order to be prepared for such an event. During a major blackout in the Electric Reliability Council of Texas (ERCOT) region in February 2011, many black-start generators were either on planned outages or failed to load during the event due to weather-related causes, including frozen sensor lines, equipment, valves or low-temperature cutoff limits.

According to a Federal Electric Reliability Commission (FERC) task force, this event shut down 210 generating units and caused system-wide rolling blackouts, which were blamed on the electrical generation owner's failure to be proactive. FERC later issued a report to ERCOT on what could be done to avoid a future blackout during another extreme weather event to possibly mitigate the loss of electrical generation. The FERC report recommended an additional heat trace, wind breaks, winterization checklists, space heaters, insulation and additional measures to avoid unit outages during extreme weather events in the future.

Industrial Info Resources (IIR), with global headquarters in Sugar Land, Texas, and eight offices outside of North America, is the leading provider of global market intelligence specializing in the industrial process, heavy manufacturing and energy markets. Industrial Info's quality-assurance philosophy, the Living Forward Reporting Principle™, provides up-to-the-minute intelligence on what's happening now, while constantly keeping track of future opportunities.