No abstract

More and more countries and utilities are trying to develop smart grid projects to make transformation of their power infrastructure towards future grids with increased share of renewable energy production and near zero emissions. The intermittent nature of solar and wind power can in general cause large problems for power system control. Parallel to this process, the aging of existing infrastructure also imposes requirements to utility budgets in the form of a need for large capital investments in reconstruction or maintenance of key equipment. Synchrophasor and other synchronized measurement technologies are setting themselves as one of the solutions for larger wind power integration. With that aim, in this paper one possible solution for wind power control through data mining algorithms used on a large quantity of data gathered from phasor measurement units (PMU) is described. Developed model and algorithm are tested on an IEEE 14 bus test system as well as on real measurements made on wind power plants currently in operation. One such wind power plant is connected to the distribution grid and the other one to the transmission grid. Results are analyzed and compared.

Increasingly higher demand in power created problems in power system operation since the growth of the transmission system is restricted. System often function close to their stability limits and sometimes loads need to be shed in order to prevent system from collapsing. In this paper one undervoltage load shedding (UVLS) method to prevent voltage collapse is presented. This method is based on a global index which indicates voltage collapse proximity and voltage magnitudes on critical buses. Global index for voltage collapse proximity determination is calculated based on power flow Jacobian matrix operations. Considering that on the voltage stability limit Jacobian matrix becomes singular, it cannot be inverted. Therefore method involving eigenvalue calculation is used here. IEEE 14 bus system was used as a numerical example which showed how loads and system in general can be saved from voltage collapse using UVLS.

After deregulation of power systems, large problems with voltage stability incurred due to the large transits of power transmitted to large distances. Systems are very stressed and often work on their limits. Therefore, single contingency is sometimes enough to cause system collapsing. One of the most economic methods to prevent larger scale voltage collapse is undervoltage load shedding (UVLS). In this article, implementation of UVLS scheme is tested in New England Test System and then modeled in part of Croatian power system. Simulation of system behavior is presented as well.

As result of electric power system liberalization, every ancillary service is worth economically. Clear and transparent rules should be determined for the evaluation of each service. Voltage control is very important ancillary services and therefore open market of reactive power becomes reality in deregulated power markets. All that has consequence in need for economic evaluation of reactive power. Also, because of location-based nature of reactive power and geographically very limited market, arises chance for so-called "market power". In this paper, one method of reactive power evaluation is presented with emphasis on market power measuring.