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The number of photovoltaic (PV) generators has been significantly increased worldwide as a main renewable energy resource. The output power of PV generators mainly depends on the solar irradiance, module temperature, and field conditions. Therefore, the maintenance of the PV system is necessary to improve the reliability in its use. In this paper, a novel method to diagnose output power lowering in a PV array is proposed to keep the good performance of its output power based on the relationships between PV module temperature, current, and voltage under maximum power point conditions. In particular, the proposed method does not require the accurate information in specification on PV module and sensors for measuring irradiation levels, which are required in conventional monitoring systems. This results in the reduction of cost. Then, it is effectively applied to a practical PV system by using the Kalman-filter algorithm. The performances of the proposed diagnosis method are evaluated and verified with the laboratory experiment and field tests as well as the PSCAD/EMTDC-based simulation test.

The photovoltaic(PV) generation system have recently become widely used to solve the environmental problems and running out of fossil fuels. However, the study on maintenance is inadequate for PV system. This paper proposes the novel diagnosis method of output power decline to maintain the normal output performance of PV array. The diagnosis method used the proportional relation of irradiation-output current(S-I) of PV array at maximum power point(MPP). And, first order polynomial using the relation is proposed to easily apply PV system. To estimate the relation in case of separation of PV array producer and diagnosis system producer. Kalman Filter algorithm is also proposed at 30.2kW grid-connected PV system. Then, the performance of diagnosis method is evaluated using the hardware tests as well as the simulation.

This paper analyzes the effect of superconducting magnetic energy storage (SMES) to improve the stability of the distribution network with a photovoltaic (PV) system and plug-in battery electric vehicles (PBEVs). The PBEVs are expected to play a major role in making the transport system. The charge of their batteries by the penetration of PBEVs results in an increase of peak demand. Also, the output power fluctuation from a large-scale PV system due to the weather conditions often causes instability of the system. To handle these problems, the SMES is applied in this paper. To analyze the effects of SMES on the system stability, several important factors such as the capacity of SMES, its regulation for grid-connection, power reserve margin, the charging scenario of battery, the output power fluctuation of the PV system, and the seasonal load demands, etc., are considered with field measurement data. The performances of the SMES are evaluated and verified with the PSCAD/EMTDC based simulation test.

This paper describes a study on the application of superconducting magnetic energy storage (SMES) and grid code compliance to a wind and photovoltaic (PV) generation system. When a grid operates under instantaneous outage or surge condition, the distributed generation systems such as wind and PV systems must remain connected to the grid during a certain period of time. Therefore, the distributed generation system should be able to operate under abnormal conditions, such as reactive power or current fluctuations, which can damage the system and critical loads. The SMES can significantly enhance the dynamic security of such distributed power systems due to its high energy density and quick response characteristics. In this paper, the SMES control strategies for a wind and PV generation system during a fault ride through condition are examined, and the dynamic performance of SMES is evaluated by a case study based on the PSCAD/EMTDC simulation.

This paper proposes a method to determine the optimal size of superconducting magnetic energy storage (SMES) to improve the stability of distribution power system with photovoltaic (PV) generation. The output power of PV system fluctuates according to changing weather conditions. Then, the system is subject to be unstable. In order to improve its stability, the SMES is applied. In general, the SMES is being considered as a strong candidate among energy storage devices in industry due to its high efficiency, fast response, and high energy density.