Evaluation of Battery System for Frequency Control in Interconnected Power System with a Large Penetration of Wind Power Generation

ABSTRACT:

Recently, a lot of distributed generations such as wind power generation are going to be installed into power systems. However, the fluctuation of these generator outputs affects the system frequency. Therefore, introduction of battery system to the power system has been considered in order to suppress the fluctuation of the total power output of the distributed generation. For frequency analysis, we use the interconnected 2-area power system model. It is assumed that a small control area with a large penetration of wind power plants is interconnected into a large control area. In this system, the tie line power fluctuation is very large as well as the system frequency fluctuation. It is shown that the installed battery can suppress these fluctuations and that the effect of battery on suppression of fluctuations depends on the battery capacity. Then, the required battery capacity for suppressing the tie line power deviation within a given level is calculated.

KEYWORDS:

  1. Battery
  2. Distributed Generation
  3. Frequency
  4. Load Frequency Control (LFC)
  5. Power System
  6. Tie Line Power
  7. Wind Power Generation

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Battery system model.

EXPECTED SIMULATION RESULTS:

(a) Tie line power flow

(b) system frequency (Area 2)

Fig. 2. Impact of LFC control method.

  • (a) Tie line power flow

(b) System frequency (Area 2)

(c) Battery output

Fig. 3. Behaviors of tie line power flow, system frequency and battery

output with/without battery (Kb = 0.5, Tb = 0.5).

(a) Tie line power flow

(b) Battery stored energy

(c) Battery output

Fig. 4 Behaviors of tie line power and output and stored energy of battery (9OMWh, 1500MW)

CONCLUSION

In this paper, we have analyzed the impact of installed wind power generation and battery on the system frequency and the tie line power. In 2-area power systems, the tie line power fluctuation is remarkably large as well as the system frequency fluctuation. It has been made clear that the installed battery can suppress these fluctuations and that the effect of battery on suppression of these fluctuations depends on battery capacity. If the stored energy of battery reaches the full capacity, the battery output changes to zero suddenly and the large fluctuation is caused. Therefore, the stored energy needs to be controlled within the rated storage capacity. Based on this need, the required battery capacity for suppressing the tie line power deviation within a reference level has been calculated. If battery and LFC generator are controlled cooperatively, installation of battery with a larger capacity makes it possible to decrease LFC capacity of the conventional generators. In the near future, a new method to calculate the optimal battery storage capacity (MWh) and the appropriate power converter capacity (MW) for various kinds of wind power generation patterns and an effective control method of the battery system for reducing the battery capacity and LFC capability of the conventional power plants will be studied.

REFERENCES:

[1] W. El-Khattam and M. M. A. Salama, “Distributed generation technologies, definitions and benefits,” Electric Power Systems Research, vol. 71, issue 2, pp. 1 19-128, Oct. 2004.

[2] N. Jaleeli, L. S. VanSlyck, D. N. Ewart, L. H. Fink, and A. G. Hoffmann, “Understanding automatic generation control,” IEEE Trans. Power Syst., vol. 7, pp. 1106-1122, Aug. 1992.

[3] A. Murakami, A. Yokoyama, and Y. Tada, “Basic study on battery capacity evaluation for load frequency control (LFC) in power system with a large penetration of wind power generation,” T. IEE Japan, vol. 126-B, no. 2, pp. 236-242, Feb. 2006. (in Japanese)

[4] P. Kunder, “Power System Stability and Control, ” McGraw-Hill, 1994.

[5] A. J. Wood and B. F. Wollenberg, “Power Generation Operation and Control,” 2nd ed., Wiley, New York, 1966.

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