However, the number of running hours for the AC–generator is high (40% of the simulation time) and the operation at part load causes a high fuel consumption. Obviously, the fraction of the total load that is covered by renewable energy is maximal in case of the AC–diesel generator, as the diesel generator is only used to fill up the difference between energy demand and supply from wind turbine and batteries. The economical assumptions can be found in table 1. The SOMES default diesel generator type has been used. The low–switch level at which the diesel generator is started was set at 35% of the battery capacity, whereas the high–switch was subsequently set at 50%, 70% and 90% SOC. The minimum and maximum allowed battery SOC were 30% and 95% of the battery capacity. A choice can be made on basis of simulation calculations, in which the diesel generator was coupled to the AC–bar, running at part load, and coupled to the DC–bar, running at full load. This raises the fuel consumption and lowers the battery life time. 90% SOC), the batteries cannot store much extra energy, in case the wind turbine should produce excess energy. ![]() If the high–switch is set to a high level (e.g. 50% SOC), the diesel generator may run often for only a short time, which increases the fuel consumption and may cause inconvenience. If it is set to a relatively low value (e.g. The optimum choice for the high–switch is less straightforward and depends among others on the load pattern. The low–switch can be set just above the minimum battery SOC that is allowed. ![]() If the diesel generator is running, it will be stopped when the batteries are recharged to a predefined level (high–switch) or if the energy production of the wind turbine exceeds the load demand. The diesel generator will be started when the state of charge (SOC) of the batteries falls below a certain predefined value (low–switch). In this strategy the diesel generator can be operated at full–load which has the advantage of a higher fuel–efficiency. As it is to be expected that most of the diesel generator production will be stored into the batteries, a diesel generator is used that is coupled to the DC–bar of the system (DC–generator). The diesel generator can supply energy to the load directly but also charge the batteries. In this configuration the diesel generator is not used to charge the batteries. As the maximum load demand (14 kW) is smaller than the nominal power of the diesel generator (25 kW) it always runs at part load. The diesel generator is coupled to the AC–bar of the system (AC–generator). When the hourly load demand exceeds the energy produced by the wind turbine plus the energy that can be supplied by the batteries, the diesel generator fills in the difference. The generator only supplies energy to the load directly. The diesel generator can be incorporated into the system in various ways: (i)
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |