A Random Forest and Current Fault Texture Feature–Based Method for Current Sensor Fault Diagnosis in Three-Phase PWM VSR

Three-phase PWM voltage-source rectifier (VSR) systems have been widely used in various energy conversion systems, where current sensors are the key component for state monitoring and system control. The current sensor faults may bring hidden danger or damage to the whole system; therefore, this paper proposed a random forest (RF) and current fault texture feature–based method for current sensor fault diagnosis in three-phase PWM VSR systems. First, the three-phase alternating currents (ACs) of the three-phase PWM VSR are collected to extract the current fault texture features, and no additional hardware sensors are needed to avoid causing additional unstable factors. Then, the current fault texture features are adopted to train the random forest current sensor fault detection and diagnosis (CSFDD) classifier, which is a data-driven CSFDD classifier. Finally, the effectiveness of the proposed method is verified by simulation experiments. The result shows that the current sensor faults can be detected and located successfully and that it can effectively provide fault locations for maintenance personnel to keep the stable operation of the whole system

A Random Forest and Current Fault Texture Feature-Based Method for Current Sensor Fault Diagnosis in Three-Phase PWM VSR

Three-phase PWM voltage-source rectifier (VSR) systems have been widely used in various energy conversion systems, where current sensors are the key component for state monitoring and system control. The current sensor faults may bring hidden danger or damage to the whole system; therefore, this paper proposed a random forest (RF) and current fault texture feature-based method for current sensor fault diagnosis in three-phase PWM VSR systems. First, the three-phase alternating currents (ACs) of the three-phase PWM VSR are collected to extract the current fault texture features, and no additional hardware sensors are needed to avoid causing additional unstable factors. Then, the current fault texture features are adopted to train the random forest current sensor fault detection and diagnosis (CSFDD) classifier, which is a data-driven CSFDD classifier. Finally, the effectiveness of the proposed method is verified by simulation experiments. The result shows that the current sensor faults can be detected and located successfully and that it can effectively provide fault locations for maintenance personnel to keep the stable operation of the whole system.Comment: Frontiers in Energy Researc

Research and application of intermittent partial discharge characteristics and easy-warning system for electric equipment

Intermittent partial discharge has become an essential threat to the safety and stability of high voltage electrical equipment. In order to reduce the sudden insulation breakdown failure due to the intermittent and latent partial discharge of the operating equipment, this paper analyzes the discharge characteristics of the intermittent partial discharge in the constant voltage mode. The UHF partial discharge spectrum of typical intermittent partial discharges is obtained, and the intermittent discharges are divided into low-risk and high-risk categories by adopting PCA and FCM cluster algorithms. Aiming at the characteristics of intermittent partial discharge and the on-line monitoring method of partial discharge, a partial discharge signal collection method based on dynamic frequency is proposed. An intelligent monitoring system of intermittent partial discharge is designed to acquire partial discharge signals initially locate defects. Then the BP neural network method is applied to automatically evaluate and early warn the internal insulation status. The test concluded that the designed monitoring system for intermittent partial discharge could dynamically track and warn the low-risk and high-risk, and evaluate the insulation status of the equipment

Sex-specific Association of Antipsychotic-induced Weight Gain and Treatment Response for Antipsychotic-Naive First Episode Schizophrenia Patients: A Prospective 8-week Longitudinal Study

Background Patients with antipsychotic-naive first-episode (ANFE) schizophrenia (SZ) can help clarify many confounding factors in determining sex differences in antipsychotic drug induced weight gain and its association with symptom improvement. Methods This 8-week longitudinal trial of ANFE patients with SZ enrolled 526 patients and 313 healthy controls. We evaluated bodyweight and the efficacy of antipsychotics on the Positive and Negative Syndrome Scale (PANSS) at baseline and at the end of week 8. Results Males and females after treatment showed no sex difference in weight gain, BMI increase, and percentage of weight gain. However, at baseline, male patients had more positive symptoms than female patients, and decreases in positive symptoms, general psychopathology, and total PANSS scores were less in male than female patients. Adjusting for confounding factors using multiple linear regression confirmed that weight gain was significantly associated with these decreases in PANSS symptoms only in men not women. Conclusions The relationship between weight gain and symptom reduction after 8 weeks of antipsychotic treatment exists only in male patients with ANFE SZ and not in female patients

Postischemic Long-Term Treatment with Qiangli Tianma Duzhong Capsule Improves Brain Functional Recovery via the Improvement of Hemorrheology and the Inhibition of Platelet Aggregation in a Rat Model of Focal Cerebral Ischemia

Qiangli Tianma Duzhong capsule (TMDZ), a Chinese herbal drug, is clinically used to improve functional outcome in patients with ischemic stroke in China. This study was conducted to establish whether postischemic long-term treatment with TMDZ could reduce the loss of injured hemisphere and confer the improvements of neurological outcome in chronic survival of rats with 2 h middle cerebral artery occlusion (MCAO)/reperfusion brain injury and its primary mechanisms. We found that TMDZ (44.5, 89, or 178 mg/kg), administered per os 6 h after the onset of ischemia and for 28 consecutive days, significantly improved the behavior deficits, beginning on day 7, and further improved later. TMDZ treatment also markedly reduced the tissue loss of the injured hemisphere and improved histopathology. In the meantime, TMDZ treatment could improve hemorrheology and inhibit platelet aggregation. These results provide the first evidence that post-ischemic long-term treatment with TMDZ confers the improvements of neurological outcome and the loss of injured hemisphere in an animal ischemic stroke model, and its mechanisms might be associated with the improvements of hemorrheology and the inhibition of platelet aggregation

Elevation and Land Use Types Have Significant Impacts on Spatial Variability of Soil Organic Matter Content in Hani Terraced Field of Yuanyang County, China

Soil organic matter (SOM) content is one of the most important indicators of the sustainability of soil. To maintain sustainable soil utilization and management in fragile Hani terraced field, it is meaningful to investigate the effects of topography and land use type on SOM content. Descriptive statistics and geostatistics were used to analyze the data and the kriging method was applied to map the spatial patterns of SOM content. The results showed that the mean SOM content was 32.76 g/kg, with a variation coefficient of 40%. The SOM content was affected by elevation and land use type. As the increase of elevation, the SOM content in Hani terraced field also increased obviously. The SOM content in tea garden, which is almost at high elevation, was the highest in all six land use types, and the SOM content decreased in a following sequence: tea garden > paddy field > corn field > banana garden > cassava field > sugarcane field. In addition, at the same elevation, the paddy field had the highest SOM content compared with other land use types. All these results demonstrate that paddy field is the most efficient and suitable land use type for SOM conservation at high, middle or low elevations in the fragile Hani terraced field. In order to protect soil quality and maintain the sustainable agricultural development, it is necessary to maintain or even to enlarge the area of paddy field in Yuanyang county, Yunnan Province, China