Insight into Participation of Generating Sources in the Energy Supply to Loads
Latvian Journal of Physics and Technical Sciences
Under the market economy conditions every producer should know the proportion of electrical energy to be delivered to a concrete load and the energy losses that arise at delivery. Any network is characterised by such parameters as loads, generated power, power from slack buses, flows in its branches, etc., which can be determined by computer programs, e.g. Mustang or Power World. However, these programs do not compute the share of a particular power plant (PP) in supplying a particular load,
... particular load, since the PPs can be involved in the load delivery in different proportions, without changing the input information on the generated power, loads and branch flows. Therefore, solution of this problem is not purely technical, and many alternative solutions are proposed, the most important among them being based on the principle of proportionality. This principle is in conflict with the notion of the injection node. If the share of a PP in the load coverage is not known, the flow of this plant in the network branches is also unknown. In the paper, it is proposed to take into account the admittance from a PP to the load, calculating the load share to be covered by this plant. The current from a PP to the load should be calculated proportionally to the admittance of the path to load, after which the admittance of the involved power line attached to a PP is determined. Such admittances take into account not only impedances of these lines but also the currents flowing from other PPs and can be calculated when in the lines not only collinear but also differing in phase currents flow; in the latter case the angle between the currents is accounted for. In such a manner, the load coverage quotient is determined that shows the load coverage to be shared by a given PP. All coverage quotients known, the address coefficients for all PPs can be calculated. This method allows more realistic calculation of the flows from PPs in a particular power line. The losses of a given PP are found by well-known formulas, assuming that a definite proportion of the phase conductor cross-section of a given line belongs to a given PP. This proportion is found taking into account all the flows in this line.