Power-Angle Modulation Controller to Support Transient Stability of Power Systems Dominated by Power Electronic Interfaced Wind Generation

Abstract

During the last few years, electric power systems have undergone a widespread shift from conventional fossil-based generation toward renewable energy-based generation. Variable speed wind generators utilizing full-scale power electronics converters are becoming the preferred technology among other types of renewable-based generation, due to the high flexibility to implement different control functions that can support the stabilization of electrical power systems. This paper presents a fundamental study on the enhancement of transient stability in electrical power systems with increasing high share (i.e., above 50%) of power electronic interfaced generation. The wind generator type IV is taken as a representative form of power electronic interfaced generation, and the goal is to investigate how to mitigate the magnitude of the first swing while enhancing the damping of rotor angle oscillations triggered by major electrical disturbances. To perform such mitigation, this paper proposes a power-angle modulation (PAM) controller to adjust the post-fault active power response of the wind generator type IV, after a large disturbance occurs in the system. Based on a small size system, the PAM concept is introduced. The study is performed upon time-domain simulations and analytical formulations of the power transfer equations. Additionally, the IEEE 9 BUS system and the test model of Great Britain’s system are used to further investigate the performance of the PAM controller in a multi-machine context, as well as to perform a comparative assessment of the effect of different fault locations, and the necessary wind generators that should be equipped with PAM controllers.

Transient Stability Performance of Power Systems with High Share of Wind Generators Equipped with Power-Angle Modulation Controllers or Fast Local Voltage Controllers

“…The input of the PAM controller attached to a wind generator type IV is the rotor angle deviation between the slack synchronous generator of the system and the synchronous generator that is electrically close to the wind generator. Interested readers can find a detailed description of the working and design principles of the PAM controller in [5]. Figure 1.…”

“…The PAM controller is implemented as a filter differentiator (i.e., washout filter, with a gain K w-PAM and a time constant T w-PAM ). As explained in [5], unlike the similar approach with power system stabilizers applied in synchronous generators, the phase compensators (i.e., lead-lag filters) are not part of the PAM controller. This compensation is obviated due to the assumption of a small phase lag between the active current reference and the active power output of the grid side converter of the wind generator type IV [5].…”

“…A previous work by the authors of this paper, published in [5], provides a review of the methods proposed so far in the existing literature to attempt to safeguard the transient stability of systems with shares of renewable power generation up to 50%. Remarkably, [5] points out that the main challenge is to ensure and reduced the amplitude of the first swing and good damping of the rotor angle oscillations that are excited by large-size disturbances. Therefore, the power-angle modulation (PAM) controller was proposed in [5] as a feasible mean to properly adjust the post-fault active power response of fully decoupled wind generators (WG) (e.g., WG system type IV).…”

“…Remarkably, [5] points out that the main challenge is to ensure and reduced the amplitude of the first swing and good damping of the rotor angle oscillations that are excited by large-size disturbances. Therefore, the power-angle modulation (PAM) controller was proposed in [5] as a feasible mean to properly adjust the post-fault active power response of fully decoupled wind generators (WG) (e.g., WG system type IV). The preliminary research results shown in [5] suggest that PAM may allow a safe increase (i.e., without causing transient instability) of the share of decoupled wind generation beyond 50%.…”

“…Therefore, the power-angle modulation (PAM) controller was proposed in [5] as a feasible mean to properly adjust the post-fault active power response of fully decoupled wind generators (WG) (e.g., WG system type IV). The preliminary research results shown in [5] suggest that PAM may allow a safe increase (i.e., without causing transient instability) of the share of decoupled wind generation beyond 50%.…”