A novel method for low-frequency oscillation suppression based on PV system

Low-frequency oscillation occurs when the transmission lines equivalent impedance is small or negative. As the increase penetration of PV system, it plays an important role for system stability. A novel method for low-frequency oscillation suppression based on PV system is proposed. Model of PV accessed to power grid is established, which reveal the relationship between output power of PV system and power oscillation of power system. Three control strategies are proposed and comparison of different methods is made. Simulation and experiment are carried out on a 50-kVA prototype to validate the practicability of control strategy.

I. Introduction

New energy is playing more and more important role in world energy strategy [1]–[2]. Nowadays research on wind power control theory is much more than PV system [3]. Research on PV system is mostly based on PV inverter control theory or modeling of PV cells. Low-frequency oscillation suppression has been researched for a short term. Most control strategies are based on power system stabilizer (PSS) or static var generator (SVG), which has an important effect in system low-frequency oscillation [4]–[5]. PV system will have a higher penetration in the future power system. If PV system can use its spare capacity to suppress power oscillation, it's very useful for its application [5].