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The objective of conventional wind power relay protections is to maintain the system's stable operation. However, the protections' selectivity is not high enough to enable the wind turbine to ride through low-voltage faults. Thus, with an increasing wind power capacity, it is required that the wind turbines possess more strict low-voltage ride-through(LVRT) ability, otherwise the stability of power...
A two-level hierarchical structure is proposed to improve the stability of multi-machine power systems. The scheme consists of a local controller for each generator at the secondary level associated by a wide-area controller at the first level. The wide-area controller is in charge of evaluating the global signals, such as the center of rotor angle, the center of rotor speed. And the local controller...
It is possible to prevent collapse of whole post-fault power system, which is in unstable condition, by determining the splitting boundary to calm down system oscillation. A fast splitting boundary-searching method for power system controlled islanding is presented in this paper. The aim of this method is that the generation load imbalance in each island is as small as possible. The method contains...
In this paper, a doubly fed induction generator (DFIG) wind turbine controller which consists of two control loops is introduced. In steady state, the main control loop ensures that the wind power generators without wind speed measurement can perform active power control tasks below the nominal wind speed while the auxiliary stability control loop restraining the wind power system oscillations by...
To improve the stability of the power system integrated of wind farm, the wind power system energy function is proposed in this paper based on the energy conservation law. Then a stability control strategy based on the energy function is introduced. The impacts of DFIG operation limits on the control effect are also discussed. By variable speed operation, the control strategy restrains the wind power...
A Doubly-Fed Induction (DFIG) wind generator dynamic model is developed in PSCAD. Then a novel active power control strategy based on the indirect speed control is introduced to implement the power control tasks and the limits of these controls are also discussed. The novel strategy ensures that wind power generators without wind speed measurement can achieve the balance control and maximum power...
Based on the transient energy function (TEF) theory with classical models considered, the optimal re-closing time (ORT) can be calculated accurately. This paper mainly focuses attention on the validity and practicability analyzing of ORT obtained from this method. Firstly, the characteristics and influencing factors of the ORT are put forward and analyzed, and also the setting strategy of re-closing...
This paper presents a new integrated protection relay and its associated scheme for distributed generation systems. In the scheme, an integrated relay is responsible for the protection of both line sections associated with the substation bus. Based on conventional directional overcurrent protection technique, the basic principle of the new relay is to determine whether a fault is on the protected...
The re-closing time of a transmission line has a distinct influence on power system transient stability. There is an optimal re-closing time (ORT) for all transmission line faults, no matter the instantaneous fault or permanent one. Based on the transient energy function (TEF) theory with classical models considered, the ORT can be calculated accurately. This paper mainly focuses attention on the...
The study of various stability-control methods for a transmission system indicates that the reclosing time of a transmission line has a distinct influence on system stability. And there is an optimal reclosing time (ORT) for all transmission line faults. Utilizing the transient energy function (TEF) with classical models considered, the ORT setting computation method is proposed. This paper shows...
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