Fig 1.
Model block diagram of the single-machine system.
Fig 2.
Operation mode transition diagrams of pumped storage units.
(a) A typical mode transition diagram. (b) The mode transition diagram for frequency control.
Fig 3.
Principle of the under-frequency load shedding.
Fig 4.
The coordination control scheme.
Fig 5.
The dynamic frequency trajectory curve for the combined system of pumped storage units and UFLS.
Fig 6.
Flowchart of the solution process.
Fig 7.
Topology of the EPRI-36 bus system.
Table 1.
Initial parameters of the pumped storage units in the EPRI-36 bus system.
Fig 8.
The frequency curve without any measures.
Fig 9.
Simulated frequency curves.
Table 2.
Two comparison schemes.
Table 3.
Simulation analysis results.
Fig 10.
Simulated frequency curves for different schemes.
Table 4.
Comparison of five different schemes.
Table 5.
Simulation analysis results.
Fig 11.
Simulated test power grid.
Table 6.
Initial parameters of pumped storage units.
Table 7.
Stage-by-stage joint control scheme.
Fig 12.
The frequency curve without any measures.
Fig 13.
Simulated frequency curves.
Table 8.
Two comparison schemes (Case 1).
Table 9.
Simulation analysis results for two schemes (Case 1).
Fig 14.
Simulated frequency curves for different schemes.
Table 10.
Comparison of five schemes (Case 1).
Table 11.
Simulation analysis results for different schemes (Case 1).
Fig 15.
Frequency variation for the 2000 MW power shortage scenario, without any recovery strategy applied.
Fig 16.
Simulated frequency curves (Case 2).
Table 12.
Comparison of two schemes (Case 2).
Table 13.
Simulation analysis results (Case 2).
Table 14.
Comparison of five schemes (Case 2).
Fig 17.
Simulated frequency curves, for the optimized scheme and the other four schemes.
Table 15.
Simulation analysis results for different schemes (Case 2).