Analysis of the Dynamic Performance of Self-Excited Induction Generators Employed in Renewable Energy Generation

Abstract

Incentives, such as the Feed-in-tariff are expected to lead to continuous increase in the deployment of Small Scale Embedded Generation (SSEG) in the distribution network. Self-Excited Induction Generators (SEIG) represent a significant segment of potential SSEG. The quality of SEIG output voltage magnitude and frequency is investigated in this paper to support the SEIG operation for different network operating conditions. The dynamic behaviour of the SEIG resulting from disconnection, reconnection from/to the grid and potential operation in islanding mode is studied in detail. The local load and reactive power supply are the key factors that determine the SEIG performance, as they have significant influence on the voltage and frequency change after disconnection from the grid. Hence, the aim of this work is to identify the optimum combination of the reactive power supply (essential for self excitation of the SEIG) and the active load (essential for balancing power generation and demand). This is required in order to support the SEIG operation after disconnection from the grid, during islanding and reconnection to the grid. The results show that the generator voltage and speed (frequency) can be controlled and maintained within the statuary limits. This will enable safe disconnection and reconnection of the SEIG from/to the grid and makes it easier to operate in islanding mode.

Power Management of Islanded Self-Excited Induction Generator Reinforced by Energy Storage Systems

“…Operation of such a system in islanded mode is stable as long as the generator is loaded by the optimal active and reactive power [32]. Initially, the SEIG should be connected to the main grid to guarantee the machine terminal induced voltage can be built up [37].…”

“…This work is an improvement of the study in [32], in which an energy storage system is used to reinforce the operation of a SEIG through management of active and reactive power to maintain its optimal load condition operation. This paper presents a control circuit designed to be able to keep the power drawn from an induction generator at the optimal values, irrespective of load variation.…”

“…There is a gap in the literature regarding the operation and robust control of SEIG in islanding mode including the transitional period from grid connection to isolation. In [32], the optimal operation performance of the SEIG is obtained using an optimum fixed combination of active and reactive load during the transitional status, however, a fixed load is unlikely to be maintained due to local load variation. Studies [33,34] have suggested using converter-based power electronic devices to maintain the operation of an islanded SEIG to fixed frequency and voltage, however they do not consider operational continuity under load variations.…”

Pengaruh Penutupan-Balik Tak-Sinkron terhadap Generator Induksi 3-Fase dalam Skema Pembangkitan Tersebar

“…Hasil simulasi tersebut memperlihatkan adanya pengaruh buruk generator induksi terhadap generator sinkron karena sifat generator induksi yang memerlukan daya reaktif. Titik operasi optimum diperoleh dengan memperhitungkan perbandingan daya reaktif dan daya nyata, baik pada keadaan stand-alone maupun connected to grid [8]. Pada penelitian-penelitian tersebut tidak dibahas keadaan saat terjadi putus-sambung generator ke grid [4]--[8].…”

“…Titik operasi optimum diperoleh dengan memperhitungkan perbandingan daya reaktif dan daya nyata, baik pada keadaan stand-alone maupun connected to grid [8]. Pada penelitian-penelitian tersebut tidak dibahas keadaan saat terjadi putus-sambung generator ke grid [4]-- [8]. Makalah ini mendiskusikan karakteristik tegangan, arus, dan daya di terminal generator induksi berkaitan dengan PBTS karena operasi PBO.…”