2013. — 10 c.Although the physics involved in the functioning of power systems have not changed, in the present time, the stability of the power system has been stressed by higher percentage loading and other imposed physical and procedural requirements. Power systems throughout the world are requiring the use of wide-area protection and control (WAPC) schemes to ensure their stability and continuous operation. Smaller microgrid or micropower systems, similar to those found in industrial installations and distributed generation, require sophisticated control schemes to maintain stability during islanding and loss of the utility tie.
Managing the overload of critical assets, such as power transformers, often requires a WAPC scheme. Power system operators study the effect of losing transmission paths on critical transformers in the power system. It is not uncommon, for example, to take action in remote locations when critical transformers become overloaded.
Overloading transmission paths can create instability in the power system, as well. The power transmitted through a transmission line is proportional to the sine function of the angle between the sending and receiving bus voltages. As angles increase, the power transfer demands a larger angle difference and a critical angle stability limit will be reached. Newer technologies that allow the referencing of two angle measurements across long distances dramatically improve the operating range and precision.
