Modeling and Analysis of SEIG-STATCOM Systems Based on the Magnitude-Phase Dynamic Method

Haifeng Wang,Xinzhen Wu,Rui You,Jia Li 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

This paper proposes an analysis method based on the magnitude-phase dynamic theory for isolated power systems with static synchronous compensators (STATCOMs). The stability margin of an isolated power system is greatly reduced when a load is connected, due to the disadvantageous features of the self-excited induction generators (SEIGs). To analyze the control process for system stability and to grasp the dynamic characteristics in different timescales, the relationships between the active/reactive components and the phase/magnitude of the STATCOM output voltage are derived in the natural reference frame based on the magnitude/phase dynamic theory. Then STATCOM equivalent mechanical models in both the voltage time scale and the current time scale are built. The proportional coefficients and the integral coefficients of the control process are converted into damping coefficients, inertia coefficients and stiffness coefficients so that analyzing its controls, dynamic response characteristics as well as impacts on the system operations are easier. The effectiveness of the proposed analysis method is verified by simulation and experimental results.

Numerical Calculation of Stator End Leakage Reactance of Permanent Magnet Machines with Concentric Winding

Xiaoqin Zheng,Wen Zhang,Xinzhen Wu,Ronggang Ni 한국자기학회 2019 Journal of Magnetics Vol.24 No.1

Concentric winding has been widely used in small capacity AC motors due to its excellent performance. In this paper, a numerical calculation method based on the magnetic vector potential is proposed to calculate the stator end leakage reactance of concentric winding. In this case, the basic unit of numerical calculation becomes the coil group rather than the coil since concentric windings have different coil sizes. The calculated stator end leakage reactance of a prototype three-phase permanent magnet machine with concentric winding is validated using the finite element method. Compared to 3D electromagnetic field calculation, the proposed method does not require a complex modeling process and is therefore highly efficient computationally, requiring only a fraction of the calculation time.

Modeling and Analysis of SEIG-STATCOM Systems Based on the Magnitude-Phase Dynamic Method

Wang, Haifeng,Wu, Xinzhen,You, Rui,Li, Jia The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

This paper proposes an analysis method based on the magnitude-phase dynamic theory for isolated power systems with static synchronous compensators (STATCOMs). The stability margin of an isolated power system is greatly reduced when a load is connected, due to the disadvantageous features of the self-excited induction generators (SEIGs). To analyze the control process for system stability and to grasp the dynamic characteristics in different timescales, the relationships between the active/reactive components and the phase/magnitude of the STATCOM output voltage are derived in the natural reference frame based on the magnitude/phase dynamic theory. Then STATCOM equivalent mechanical models in both the voltage time scale and the current time scale are built. The proportional coefficients and the integral coefficients of the control process are converted into damping coefficients, inertia coefficients and stiffness coefficients so that analyzing its controls, dynamic response characteristics as well as impacts on the system operations are easier. The effectiveness of the proposed analysis method is verified by simulation and experimental results.

Sodium nitrate modified SBA-15 and fumed silica for efficient production of acrylic acid and 2,3-pentanedione from lactic acid

Junfeng Zhang,Weijie Ji,Chak-Tong Au,Xinzhen Feng,Yuling Zhao 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

The catalytic conversion of lactic acid to acrylic acid and 2,3-pentanedione over sodium nitrate-supported mesoporous SBA-15 and fumed silica was studied. The yields of acrylic acid, 2,3-pentanedione, and acetaldehyde are 44.8%, 25.1%, and 13.3%, respectively, over the 23%NaNO3/SBA-15 catalyst. The performance of the catalysts is strongly affected by NaNO3 loading, catalyst texture and porosity, and product diffusion efficiency. A proper control of NaNO3 loading can result in modification catalyst structure for improvement of 2,3-pentanedione selectivity. Under certain reaction conditions, the surface NaNO3 species can readily transform to sodium lactate that functions as active component to catalyze the target reactions.

A New Colorimetric Sensor for Cysteine Determination Based on Dual Reacting-mediated Strategy

Honghong Rao,Ying Li,Guoliang Zhang,Zhonghua Xue,Guohu Zhao,Shengyin Li,Xinzhen Du 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.9

Rapid and simple determination of cysteine is a key requirement for both diagnosis and treatment of diseases. A novel concept is proposed for combining dual reacting-mediated process into the construction of a simple yet effective colorimetric strategy for cysteine detecting, which is based on the analyte-induced formation of ferrous ion and graphene oxide-supported ionic recognition through selective coordination process between phenanthroline molecule and ferrous ion. In colorimetric analysis, the simple principle of ferrous ion that cysteine-induced can be recognized by phenanthroline indicator due to their good binding affinity and therefore provided a sensitive optical readout for conveniently detecting cysteine. Proof-concept experiments demonstrate that the proposed colorimetric system shows rapid response toward cysteine determination as well as with a satisfying detection limit of 4.8 μM only by using simple UV–Vis spectroscopy and 15 μM with the naked eye.

Initial Position Detection of Permanent Magnet Synchronous Machines with Self-Tuning Extended State Observer

Yawei Wu,Yifan Cui,Ronggang Ni,Shuxin Nie,Xinzhen Wu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The performance of the initial rotor position detection of Permanent Magnet Synchronous Machines (PMSMs) at standstill depends much on the position observer. In this paper, the Extended State Observer (ESO) is compared with the traditional Proportional Integration (PI) observer adopting the rotating high frequency voltage injection algorithm, and the observer parameter design method is derived based on the bandwidth analysis of the close-loop transfer function. Experiments are carried out on a 3 kW PMSM prototype for verifications.

Experimental Study on Frequency Support of Variable Speed Wind Turbine Based on Electromagnetic Coupler

Rui You,Jianyun Chai,Xudong Sun,Daqiang Bi,Xinzhen Wu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

In the variable speed Wind Turbine based on ElectroMagnetic Coupler (WT-EMC), a synchronous generator is coupled directly to the grid. Therefore, like conventional power plants, WT-EMC is able to inherently support grid frequency. However, due to the reduced inertia of the synchronous generator, WT-EMC is expected to be controlled to increase its output power in response to a grid frequency drop to support grid frequency. Similar to the grid frequency support control of Type 3 or Type 4 wind turbine, inertial control and droop control can be used to calculate the WT-EMC additional output power reference according to the synchronous generator speed. In this paper, an experimental platform is built to study the grid frequency support from WT-EMC with inertial control and droop control. Two synchronous generators, driven by two induction motors controlled by two converters, are used to emulate the synchronous generators in conventional power plants and in WT-EMCs respectively. The effectiveness of the grid frequency support from WT-EMC with inertial control and droop control responding to a grid frequency drop is validated by experimental results. The selection of the grid frequency support controller and its gain for WT-EMC is analyzed briefly.

Experimental Study on Frequency Support of Variable Speed Wind Turbine Based on Electromagnetic Coupler

You, Rui,Chai, Jianyun,Sun, Xudong,Bi, Daqiang,Wu, Xinzhen The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

In the variable speed Wind Turbine based on ElectroMagnetic Coupler (WT-EMC), a synchronous generator is coupled directly to the grid. Therefore, like conventional power plants, WT-EMC is able to inherently support grid frequency. However, due to the reduced inertia of the synchronous generator, WT-EMC is expected to be controlled to increase its output power in response to a grid frequency drop to support grid frequency. Similar to the grid frequency support control of Type 3 or Type 4 wind turbine, inertial control and droop control can be used to calculate the WT-EMC additional output power reference according to the synchronous generator speed. In this paper, an experimental platform is built to study the grid frequency support from WT-EMC with inertial control and droop control. Two synchronous generators, driven by two induction motors controlled by two converters, are used to emulate the synchronous generators in conventional power plants and in WT-EMCs respectively. The effectiveness of the grid frequency support from WT-EMC with inertial control and droop control responding to a grid frequency drop is validated by experimental results. The selection of the grid frequency support controller and its gain for WT-EMC is analyzed briefly.