Stochastic Energy Scheduling in Microgrids With Intermittent Renewable Energy Resources

Wencong Su,Jianhui Wang,Jaehyung Roh IEEE 2014 IEEE transactions on smart grid Vol.5 No.4

<P>Renewable energy resources such as wind and solar are an important component of a microgrid. However, the inherent intermittency and variability of such resources complicates microgrid operations. Meanwhile, more controllable loads (e.g., plug-in electric vehicles), distributed generators (e.g., micro gas turbines and diesel generators), and distributed energy storage devices (e.g., battery banks) are being integrated into the microgrid operation. To address the operational challenges associated with these technologies and energy resources, this paper formulates a stochastic problem for microgrid energy scheduling. The proposed problem formulation minimizes the expected operational cost of the microgrid and power losses while accommodating the intermittent nature of renewable energy resources. Case studies are performed on a modified IEEE 37-bus test feeder. The simulation results demonstrate the effectiveness and accuracy of the proposed stochastic microgrid energy scheduling model.</P>

Commutation Compensation for Matrix based Rectifiers due to Leakage Inductances of Isolation Transformer

Tao Zhao,Jianhui Su,Dewei (David) Xu,Meiqin Mao 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes a compensation method for isolated matrix based rectifiers. The line side THD and output voltage isolated matrix rectifier are mainly affected by the commutation delay due to transformer leakage inductances. Since DC output voltage is usually regulated by a close loop controller. But the grid side current is affected by the commutation delay. The transformer leakage inductances increases the commutation delay which reduces actual dwell time of the active vector, causes distortion on grid side current with higher current THD. The proposed compensation method takes the commutation time into consideration and extends the dwell time for active vector properly. The algorithm has been verified by simulation results.

Autonomous Controller Based on Synchronous Generator dq0 Model for Micro Grid Inverters

Yan Du,Jianhui Su,Meiqin Mao,Xiangzhen Yang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

the parallel operation of voltage source inverter (VSI) in microgrid could benefit from characteristics of synchronous generator (SG) such as the kinetic energy stored in rotor, the self-isochronous and the droop characteristics if inverter can behave like generator in power system. Therefore an autonomous controller based on dq0 model of SG for microgrid inverter is proposed to mimic the above those characteristic of SG. Moreover, the inverter is designed to serve as either UF node or PQ node in micro grid by integrating a virtual primary frequency regulator (VPFR) and a virtual excitation regulator (VER) in the proposed controller. The results of simulation show the excellent performances of the proposed autonomous controller on voltage regulation, power sharing and seamless mode transfer.

Equivalent and identification of integrated coupling parameter of variable speed constant frequency brushless doubly fed generator

Yiding Wang,Jianhui Su,Jidong Lai,Bao Xie,Yong Shi,Hongru Yu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.1

Brushless doubly fed generator (BDFG) generally adopts double closed-loop vector control strategies. Owing to the influence of BDFG coupling parameters, the accuracy of feedforward decoupling parameters is very important; however, the complexity of the BDFG model makes its winding parameters difficult to identify. On the basis of the characteristics of the BDFG system control model and the decoupling control conditions, this study proposes a method for identifying the integrated coupling parameter. This method first uses particle swarm optimization to identify the coefficients of the current closed-loop transfer function. Then, the values of the integrated coupling parameters are calculated on the basis of the relationship between the coefficients of the current closed-loop transfer function and the integrated coupling parameters of the BDFG. This method bypasses the challenge of directly identifying BDFG winding parameters and can be used directly to design the controller. Experiments are performed using a 30 kW BDFG platform to prove the feasibility and effectiveness of the proposed method.

Granularity and Laxative Effect of Ultrafine Powder of Dendrobium officinale

DanDan Luo,Chao Qu,ZhenBiao Zhang,JianHui Xie,LieQiang Xu,HongMei Yang,CaiLan Li,GuoSheng Lin,HongFeng Wang,ZiRen Su 한국식품영양과학회 2017 Journal of medicinal food Vol.20 No.2

Constipation is a common disorder that is a significant source of morbidity among people around the world ranging from 2% to 28%. Dendrobium officinale Kimura et Migo is a traditional herbal medicine and health food used for tonicity of the stomach and promotion of body fluid production in China. This study aimed to prepare the ultrafine powder of Dendrobium officinale (UDO) and investigate its laxative effect and potential mechanism in mice with diphenoxylate-induced constipation. Results indicated that the mean diameter (d50) of UDO obtained by ball milling was 6.56 lm. UDO (62.5, 125, and 250 mg/kg, p.o.) could significantly enhance the gastrointestinal transit ratio and promote fecal output. Moreover, UDO treatment resulted in significant increases in the serum levels of acetylcholinesterase (AChE), gastrin (Gas), motilin (MTL), and substance P (SP), and obviously decreased serum contents of somatostatin (SS). Taken together, UDO, which can be easily obtained through milling to a satisfactory particle size, exhibited obvious laxative effect in diphenoxylate-induced constipated mice, and the mechanism might be associated with elevated levels of AChE, Gas, MTL, SP, and reduced production of SS. UDO has the potential for further development into an alternative effective diet therapy for constipation.

Angelica sinensis Supercritical Fluid CO2 Extract Attenuates D-Galactose-Induced Liver and Kidney Impairment in Mice by Suppressing Oxidative Stress and Inflammation

Zhi-Zhun Mo,Zhi-Xiu Lin,ZiRen Su,Lin Zheng,Hui-Lin Li,JianHui Xie,Yan-Fang Xian,Tie-Gang Yi,Shui-Qing Huang,Jian-Ping Chen 한국식품영양과학회 2018 Journal of medicinal food Vol.21 No.9

Angelica sinensis (AS, Danggui in Chinese) is an important herbal component of various traditional formulae for the management of asthenia and its tonic effects. Although AS has been shown to ameliorate cognitive damage and nerve toxicity in D-galactose (D-gal)-elicited senescent mice brain, its effects on liver and kidney injury have not yet been explored. In this work, mice were subjected to hypodermic injection with D-gal (200 mg/kg) and orally gavaged with AS (20, 40, or 80 mg/kg) once a day for 8 successive weeks. Results revealed that AS significantly improved liver and kidney function as assessed by organ index and functional parameters. In addition, AS pretreatment effectively ameliorated the histological deterioration. AS attenuated the MDA level and markedly enhanced the activities and gene expressions of antioxidative enzymes, namely Cu, Zn-SOD, CAT, and GPx. Furthermore, AS markedly inhibited the D-gal-mediated increment of expressions of inflammatory cytokines iNOS, COX-2, IκBα, p-IκBα, and p65 and promoted the IκBα expression level in both hepatic and renal tissues. In sum, AS pretreatment could effectively guard the liver and kidney of mice from D-gal-induced injury, and the underlying mechanism was deemed to be intimately related to attenuating oxidative response and inflammatory stress.

Online broadband grid impedance estimation method based on multi‑objective optimized random PWM

Yan Du,Shiyou Yang,Chunran Gao,Xiangzhen Yang,Houbo Wu,Jianhui Su 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.12

Grid-connected inverter (GCI)-based online grid impedance estimation (GIE) can be used in the fields of grid state monitoring, fault diagnosis, and the stability control of grid-connected equipment, which can collectively improve the intelligence of GCI. However, the available frequency range of GCI-based GIE is limited by the bandwidth of the controller because a perturbation signal is injected into the reference current. To broaden the bandwidth of grid impedance estimation, an online GIE technology based on multi-objective optimized random pulse width modulation (MOO-RPWM) is proposed in this paper. Besides taking advantage of the harmonic dispersion characteristic of RPWM, the distribution of the switching frequency is further optimized by the constraints on the measurement accuracy and the total harmonic distortion (THD) of the grid current. Moreover, the frequency boundary is constrained by the frequency range of GIE, the stability of the system, and power loss. A genetic algorithm (GA) is applied to obtain the switching frequency sequence that satisfies the optimization targets. A single-phase grid-connected inverter system is built on a StarSim hardware-in-the-loop (HIL) platform to verify that MOO-RPWM-based GIE has the advantages of a broad GIE range, high accuracy, and low disturbance.