Discrete Time Simulation of Electrical Power Network with Intermittent Generation

Hybrid systems including wind, solar, batteries and diesel generation have been develop in various places to apply the complementary strengths of each source. In the daytime, when there is less wind, the solar panels will cover the extra load. At night, the wind turbines will be generating more power. If the solar panels and wind turbines do not create enough power, the diesel generator will automatically run to compensate for the deficiency and batteries, as storage, will help to reduce the burden of the diesel generator. Since the back-up generators are fuelled by diesel and turn on only when needed, this can actually save a lot on fuel cost. Such a situation can be modelled and simulated using a Stepwise Power Flow method created in the MatPower package and executed with MATLAB. Then the system can be optimized and monitored to achieve the best hybrid system. Regular power flow calculations assume balance between scheduled generation and actual load, but this is formally correct only once, or a few times, during the hour in a real power system, where the load is always changing. A basic Stepwise Power Flow method is demonstrated by using a modified IEEE 30-BUS test system as the sample system, the load is changed following the load demand through a day, while schedule generation is changed only at the change of hour. The loads on a power system consist of a variety of electrical devices. Some of them are purely resistive; some are motor loads with variable power-frequency characteristics, and others exhibit quite different characteristics. Since motor loads are a dominant part of the electrical load, there is a need to model the effect of a change in frequency on the net load drawn by the system and this will be simulated.