A Simple Active and Reactive Power Control for Applications of Single-Phase Electric Springs

ABSTRACT

Aiming at effective power management in micro grids with high penetration of renewable energy sources (R E S s), the paper proposes a simple active and reactive power control for the so-called second-generation, single-phase electric springs (ES-2), that overcomes the shortcomings of the existing Electric  Springs control methods. By the proposed control, the unpredictable power generated from R E S s is divided into two parts, i.e. the one absorbed by the ES-2 that still varies and the other injected into the grid that turns to be controllable, by a simple and accurate signal manipulation that works both at steady-state and during RES transients.

It

is believed that such a control is suitable for the distributed power generation, especially at domestic homes.  In the paper, the proposed control is supported by a theoretical background. Its effectiveness is at first validated by simulations and then by experiments. To this purpose, a typical RES application is considered, and an experimental setup is arranged, built up around an Electric Springs -2 implementing the proposed control. Testing of the setup is carried out in three steps and proves not only the smooth operation of the Electric Springs-2 itself, but also its capability in running the application properly.

 

KEYWORDS

  1. Electric springs
  2. Smart load
  3. Microgrids
  4. active and reactive Power control
  5. Grid connected
  6. Distributed generation.

 

SOFTWARE:  MAT LAB/SIM U LINK

 

CIRCUIT DIAGRAM:

Fig. 1: Topology of Electric Springs -2 and associated circuitry

EXPECTED SIMULATION RESULTS

Fig. 2: Simulation wave forms under different variations of the input active power. (a) From 1.6 kW to 1.1 kW and then back to 1.6 kW @ VG=230 V. (b) From 8 kW to 2 kW and then back to 8 kW @ VG=200 V. (c) From 8 kW to 4 kW and then to 2 kW @ VG=200 V.

Fig. 3: Transient ES-2 responses to a change of the line voltage with Pinref=1.5kW. (a) From 240V to 210V. (b) From 210V to 240V.

Fig. 4: Simulation waveforms before and after grid distortion. (a) Results of PLL. (b) Results of active and reactive power of ES system.

CONCLUSION

The input active and reactive power control is proposed for the purpose of practical application of ES-2 in this paper. An overall review and analysis have been done on the existing control strategies such as δ control and RCD control, revealing that the essences of the controls on ES-2 are to control the input active power and reactive power. If being equipped together with the distributed generation from RESs, the ES-2 can manage the fluctuated power and make sure the controllable power to grid, which means that the ES-2 is able to deal with the active power captured by MPPT algorithm.

Simulations

have been done on the steady and transient analysis and also under the grid anomalies, validating the effectiveness of the proposed control. Three steps have been set in the experiments to verify the three typical situations and namely the active power generated by the GCC from RESs are, 1) more than; 2) less than; 3) the same as the load demand. Tested results have validated the proposed active and reactive power control.

 

REFERENCES

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  • Wang, and D. N. Truong, “Stability enhancement of a power system with a PMSG-based and a DFIG-based offshore wind farm using a SVC With an adaptive-network-based fuzzy inference system,” IEEE Trans. Ind. Electron., vol. 60, no. 7, pp. 2799–2807, Jul. 2013.
  • active and reactive power control projects

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