Grid Operations

Nexant software applications are today critical to safe and reliable grid operations. With changing flow patterns emanating from the deregulated markets, distributed generation and demand response, it is now essential to better analyze and predict the level of security of the transmission grid.

State estimation is performed by GEN-SE®, a generalized state estimator algorithm with unique strengths related to bad data detection and rapid resolution of topology and parameter errors. A companion application, TOPAZ®, calculates topology errors, such as misread breaker status, using an innovative algorithm developed in partnership with EPRI.

Once a correct state of the grid is obtained, a rapid contingency analysis is performed to determine whether the grid can sustain a single contingency (N-1 security). With Nexant's versatile SCOPE® software, this analysis is not only accurate and fast, but can be performed with additional flexibility, such as a dynamic list of contingencies that can be changed based on operator rules. N-2 security can be instantaneously performed by moving a selected contingency in the base case between two alternative executions of the online security calculation.

Grids are also constrained by the short-circuit duties of breakers, particularly in dense areas such as large cities. FLASH® is the world best online short-circuit analysis software for estimating in real time the margin of security with respect to short-circuit limits.

Predicting and optimizing the grid in real time has been a challenge in control centers. With Nexant's optimal power flow application, SCOPE, operators can confidently rely on calculated recommendations for reactive power dispatch and other control changes to achieve optimum goals-such as minimizing losses, maintaining voltages, etc.

As grids become more interconnected and cascading outages are more probable, operators must be keenly aware of the external world. This encompasses the interconnected grid that operators may not control, but which may dramatically impact operator decisions. With Nexant's MODELEX® software, the external world is accurately represented within the control center, so that contingency analysis will remain 100% accurate while the total model size remains relatively small. MODELEX has proven many times that:

• Current external models in control centers are dangerously wrong and misleading
• It is not necessary to model external networks in their entirety to achieve 100% accuracy

Outage coordinators are a specialized team within a control center organization. Their role is increasingly visible as NERC in the U.S. and UCTE in Europe impose stricter reliability standards that must be complied with. Outage coordinators often make planning decisions within a very short timeframe.