In the paper, Markov chains in conjunction with Monte Carlo simulation are used to predict the power system security level. The new approach uses a Markov chain for each identified security range to track the development of security level through time. Based on the forecasted and recorded data, the proposed procedure offers a useful tool to the system operator to predict a future power system security level. The method has been tested on the Bosnian power system using the recorded data on security levels during a one-year period. The forecasted results show a striking coincidence with the real security levels. By means of a simple and computationally fast method, the system operator can estimate the probability of a power system blackout. The presented method could be incorporated in the wide-area monitoring system in control centers.

This paper describes two new methods of evaluating the generation ready-reserve (RR) capacity. RR is the part of the operating reserve which relates to cold fast start-up generating units. RR is important for the maintenance of the security and adequacy parameters. The first method is based on the stochastic-deterministic computation of the required RR in discrete time intervals. This approach takes into consideration the stochastic character of the change of load and generation possibilities in run and small accumulation hydro plants, and outages of each generator separately. The application of this method makes it clear to the power system operator how much of the ready reserve power to engage so as to compensate for the power deficit caused by outages of the generators for each discrete time interval. The second method is based on the Monte Carlo simulation procedure. It is an iterative probabilistic procedure which is fed by the indices of demand not supplied caused by any outages of generators (DNS). Carried out for each generating point (GP), i.e. for each power plant, the method results in the capacities of RR needed to compensate power deficits caused by the mentioned outages. This method can be used in determining the ways of improving a power system's reliability indices and in planning for the generation reserve.

The porosity of power system high-voltage transmission lines is presented through the lens of the problem of voltage stability. The ability of transmission lines to receive and transport electric energy to load centers is determined based on the well-known relationships between the characteristic variables in the field of voltage stability. Using a simple procedure, it is possible to trace the effect of electrical power flows on power system transmission line porosity and detect unstable voltage states. Through the proposed approach, the planners and operators of transmission lines can continually calculate the effect of current power flows and transmission topology on the ability of transmission lines to receive more electric power without endangering the voltage stability and desired voltage profiles throughout a given system. Therefore, the results of the presented algorithm can operate in a manner to utilize the inherent available margins of the existing and planned transmission lines.