A new controlled superconducting magnetic energy storage for dynamic stabilization of distributed generation in islanding mode of operation

Abstract

Summary According to IEEE std. 1547, islanding mode is “a condition in which a portion of an Electric Power System (EPS) is energized solely by one or more local EPSs through the associated Point of Common Coupling (PCC) while that portion is electrically separated from the rest of the area EPS”. Therefore, the dynamic instability due to islanding may result in power swing and finally loss of synchronism. Hence, many studies have been done for islanding detection and disconnection of distributed generation (DG) in an EPS. But, these conventional methods eventually lead to the disconnection of the DG units. To improve DG dynamic stability, superconducting magnetic energy storage (SMES) can be used effectively, because SMES have a high‐energy density and fast response. This paper proposes a new method to damp the power swing after DG islanding and to maintain synchronism conditions based on SMES. Hence, the disconnection of the DG units is not required. Also, new controllers are developed for SMES including voltage source converter (VSC), and DC‐DC chopper. The controller structures of VSC and DC‐DC chopper are of PI and fuzzy logic‐based type, respectively. Superconducting coil charging is controlled by the DC‐DC chopper. SMES sizing is performed, based on power swing equations. Hereupon, dynamic load model is considered. Performance of the proposed method is evaluated by defining 12 scenarios such as strong and weak networks with load changing simulated in PSCAD. Simulation results show that the islanded DG stabilization (IDGS) method has good performance to maintain stability margin in a weak network.

Sustainable protection coordination in presence of distributed generation with distributed network

“…Distributed generations (DG) are getting penetration in existing power systems because of their economical, technical, and environmental benefits to meet the electricity demand with maximum efficiency . DGs integration in the system may impose unfavorable technical limitations on effective performance of huge power system . With the integration of DGs, the fuse recloser coordination may be lost because of unintended fault current contribution by DGs, which can convert temporary faults into permanent faults.…”

“…But in this way, the DGs will be disconnected every time even in the case of temporary faults, which can hurt the reliability and introduce voltage sag problems when the size of DGs is large. The authors in Kimiai et al, Zhang et al, and Guo et al proposed different techniques especially superconducting magnetic energy storage (SMES) and solutions for islanded mode of operation in case of faults, but islanding operation might endanger the safety of utility personnel and public, leading to poor quality of power supply to customers. Moreover, DG units may get damaged because of wrong restoration of grid …”

Superconductor magnetic energy storage system usage for distributed generation: Active/reactive power and voltage controller design in connected and disconnected cases

“…The DGs can operate in connected or disconnected cases where the system stability is an important issue in both cases. In Kaimi‐Asadi et al, an SMES‐based DG is considered for stability studying in islanding mode and a new control method is proposed. Generally, harmonically nature of the renewable generation sources produce nonsmooth power flow that can significantly affect the operation of the electrical grid .…”