Wide-area damping control method for DFIG and SSSC coordination power system

[0096] Example:

[0097] choose as Figure 7 Four-machine two-area system verification including DFIG and SSSC. The wind farm consists of 10 double-fed wind turbines with a rated capacity of 1.5MW. The capacity of SSSC is 100MVA, and the specific parameters are configured as follows: the fuzzy parameters in SSSC are Kp(s)=1/(0.02s+1), Kq(s)=280/(0.001s+1). Fuzzy sets are defined as: Negative Big (NB), Negative Small (NS), Zero (ZO), Positive Small (PS), Positive Big (PB). The damping control method combining DFIG and SSSC, the fuzzy control parameters of SSSC are Kp(s)=1/(0.02s+1), Kq(s)=280/(0.001s+1). The PSS parameters of DFIG are K=-50, T1=0.5, T2=0.2, T3=8, T4=2.4, Vsmin=-0.5, Vsmax=0.5.

[0098] Table 1 Fuzzy rule table

[0099]

[0100] Case 1: Comparison of different control strategies under large disturbance three-phase short circuit

[0101] Assume that a three-phase short-circuit fault occurs in 1s at the busbar 101 of the tie line, and the fault lasts for 0.2s. When both DFIG and SSSC are not put into additional damping control, the matrix beam algorithm is used to identify the system oscillation parameters of the rotor angular velocity signal of generator G1. The oscillation frequency is 0.4369Hz, the damping ratio is 0.2942, and the system damping is not strong. If it is necessary to strengthen the system damping In this situation, the additional fuzzy damping control link in SSSC can be used. When the threshold ε is set to 0.3, after the fuzzy damping control link of SSSC is used, the oscillation parameters of the system can be identified, and the damping ratio becomes 0.3116. It can be seen that only the fuzzy damping control link of SSSC is used Damping control can meet the requirements. If the requirements for the system damping level are high, the damping provided by SSSC may be limited, and the PSS additional damping control link of DFIG needs to be further invested. If the threshold ε is set to 0.31, the damping control links of DFIG and SSSC are both put into use, and the identification system After the wide-area damping control combined with DFIG and SSSC is put into use, the damping ratio of the system becomes 0.3296, which shows that the damping of the system is improved. At the same time, the active power of the tie line of the system and the active power of the G3 generator under the three conditions of DFIG and SSSC without additional damping control, single SSSC fuzzy control, and wide-area damping control combined with DFIG and SSSC are as follows: Figure 8 and Figure 9 shown.

[0102] Depend on Figure 8 and Figure 9 It can be seen that under the wide-area damping control of the power system combined with DFIG and SSSC, the oscillation of the active power of the interval tie line and the synchronous machine has been effectively suppressed. The power recovery is smooth, the adjustment time is short, and it can quickly return to a stable state. The wide-area damping control method proposed in this paper can effectively control the power oscillation of the system, and the control effect is better than that of the SSSC fuzzy damping control alone, so that the system oscillation can be effectively suppressed.

[0103] Computational comparison of different methods and example simulation verification show that the control method is efficient and practical.