Abstract: Given the current operating condition of a power-generating system (obtained from real-time data), the near-term (e.g., after 25 min.) load demand at each bus (obtained from short-term load forecast) and the generation dispatch (based on economic dispatch), a load margin measure (MW and/or MVAR) is determined in order to assess the system's ability to withstand the forecasted load and generation variations. The invention has a method to predict near-term (e.g., after 25 min.) system voltage profiles. The proposed look-ahead measure and/or the system voltage profiles are then applied to contingency selections for the near-term power system, in terms of load margins to collapse and bus voltage magnitudes. The proposed load margin measure and the voltage profiles are based on the power flow technique and the saddle-node bifurcation theory.

Abstract: The present invention features a direct, closed-loop method for controlling an unbalanced, power-distribution network having a great number of nodes, branches and laterals, as well as multiphase loads. The network has a radial structure. One or more formulae are first derived for a power-distribution network. The formulae may be an explicit loss formula, a voltage formula, a line flow formula or any combination thereof. Network flow programming techniques which incorporate the formulae are then developed to directly achieve steady state. Finally, the control steps are performed on the power-distribution network in real time to control its operation. The control steps may include placing a capacitor, regulator or switch at a specific position in the network and/or reconfiguring the network in some other manner.

Abstract: A method for on-line dynamic contingency screening of electric power systems employs a sequence of contingency classifiers which are based on a method for finding the controlling unstable equilibrium point of the power system known as the boundary of stability region based controlling unstable equilibrium point method (BCU method). Dynamic security assessment of the power system is accomplished by evaluating the power system's response to a plurality of postulated disturbances known as contingencies. The BCU classifiers determine which of these contingencies are definitely stable, and require no further analysis. Other contingencies which are either classified as being unstable or undecided are then applied to a time-domain simulation program to determine if they are in fact unstable, and therefor warrant further action.

Abstract: The present invention features a method for determining a performance index for each power-generating system, directly correlated to load demands. This performance index can be easily interpreted by power engineers and operators, so that weak areas and potential voltage collapse conditions can be predicted and corrected. When the underlying cause of collapse is due to load variations, the performance index of the current invention has the ability to assess the amount of load increase that the system can tolerate prior to such collapse. When the underlying collapse mechanism is due to a contingency, the performance index of this invention can measure its severity. The performance index of this invention can also assess whether the system can sustain a contingency without collapse.

Abstract: A fast and reliable method for determining power system transient stability is presented for on-line power system dynamic security assessment. This method is based on the direct (Lyapunov theory) approach controlling the unstable equilibrium point (UEP). Lyapunov technique, however, cannot be used on-line, since calculating the controlling UEP is a computational intensive problem, even for a computer. The invention comprises determining the controlling UEP of a reduced system and relates the controlling UEP of the reduced system to the controlling UEP of the original system. The invention has a sound theoretical basis. The invention eliminates the difficulty of having to find the controlling UEP. The method of the invention determines the constant energy region that surrounds the controlling UEP of the original system. This region is used to approximate the stability region boundary intersection point that a particular fault trajectory will traverse.