This paper presents the automatic reactive power control of isolated wind–diesel hybrid power systems having a permanent-magnet induction generator for a wind energy conversion system and a synchronous generator for a diesel generator set. To minimize the gap between reactive power generation and demand, a variable source of reactive power is used such as a static synchronous compensator. The mathematical model of the system used for simulation is based on small-signal analysis. Three examples of the wind–diesel hybrid power system are considered with different wind power generation capacities to study the effect of the wind power generation on the system performance. This paper also shows the dynamic performance of the hybrid system with and without change in input wind power plus 1% step increase in reactive power load.
- Permanent-magnet induction generator (IG) (PMIG)
- Static synchronous compensator (STATCOM)
- Synchronous generator (SG)
- Wind–diesel hybrid system
Fig. 1. Single line diagram of an isolated wind–diesel hybrid power system.
EXPECTED SIMULATION RESULTS:
Fig. 2. Transient responses of the system (W-D with IG) for 1% step increase in load, with no change in input wind power.
Fig. 3. Transient responses of the system (W-D with PMIG) for 1% step increase in load, with no change in input wind power.
Fig. 4. Transient responses of the W-D systems with IG for 1% step increase in load plus 1% step increase in input wind power.
Fig. 5. Transient responses of the W-D systems with PMIG for 1% step increase in load plus 1% step increase in input wind power.
Fig. 6. Transient responses of the W-D1 systems with PMIG/IG for 1% step increase in input wind power plus the following: (S1) WECS uses PMIG and 10% step increase in load, (S2) WECS uses PMIG and 5%step increase in load, and (S3) WECS uses IG and 5% step increase in load.
Fig. 7. Transient responses for voltage deviations of W-D1 system without STATCOM when WECS uses PMIG for step load disturbances of (C1) 10%, (C2) 5%, and (C3) 1%.
Fig. 8 Transient responses for voltage deviations ofW-D1,W-D2, andW-D3 with STATCOM when WECS uses PMIG for 50% step load disturbances.
Reactive power control of isolated wind–diesel hybrid power systems has been investigated when WECS uses PMIG for power generation. The WECSs are interconnected to diesel generation-based grid for the enhancement of capacity and fuel saving. The system also comprises STATCOM for reactive power support during steady-state and transient conditions. A mathematical model of the system has been derived for investigating the dynamic performance of the system. For comparison of performance with the existing systems, WECS has also been considered with IG for power generation. Three examples of wind–diesel systems with different wind power generation capacities have been considered for study. It has been observed that the STATCOM effectively stabilizes the oscillations in less than 0.01 s, caused by disturbances in reactive power load and in input wind power.
As steady-state condition is reached, the STATCOM provides the additional reactive power required by the system. It has also been observed that, as the unit size of the wind-power generation decreases, the value of the optimum gain setting increases. The W-D systems with PMIG have the added advantage of reduction in the size of the STATCOM but have comparable transient performance when W-D system uses IG for power generation. The PMIG also has higher efficiency than the IG. Therefore, PMIGs are very good options for W-D systems than IG.
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