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Background and Aims: The features of non-viral, nonalcohol hepatocellular carcinoma (NBNC-HCC) remain elusive. The aim of this study was to investigate this clinical characteristics and overall survival of NBNC-HCC compared to hepatitis B- (HBV-HCC) and hepatitis C-related (HCV-HCC) HCC.Methods: We analyzed the etiologies, fibrosis stages, clinical data, and outcomes of newly diagnosed patients with HCC.Results: A total of 1777 HCC patients were recruited, including 332 patients with NBNC-HCC, 682 patients with HBV-HCC, 680 patients with HCV-HCC, and 83 patients with HBV/HCV HCC. Patients with NBNC-HCC were older (69.9 ± 11.9 years). Patients with NBNC-HCC exhibited a higher prevalence of diabetes (43.9%) compared to the HBV-HCC (27.1%, p < 0.05) and HCV-HCC (30.2%, p < 0.05) groups. Compared to patients from the viral-related HCC groups, patients with NBNC-HCC exhibited a significantly lower fibrosis stage. NBNC-HCC patients exhibited a higher proportion of Barcelona Clinic Liver Cancer (BCLC) classification stage C and stage D compared to patients from the HBV-HCC and HCV-HCC groups. With a mean of 2.33 ± 2.31 years of follow-up, the median survival of patients with NBNC-HCC was 1.75 (95% CI 1.33-2.17) years, which was significantly lower than that of patients with HBV-HCC (p = 0.041) and HCV-HCC (p < 0.001).Conclusions: Patients with NBNC-HCC have a higher risk of diabetes than patients with HCC of viral etiologies. Although patients with NBNC-HCC exhibited a milder fibrosis stage, their more advanced HCC stages and worse overall survival should be taken into consideration in clinical care. [ABSTRACT FROM AUTHOR]

Abstract This paper discusses the power variation of photovoltaic power plant (PVPP) impact on the frequency response of an isolated island microgrid. An island microgrid with PVPPs and diesel generators is selected for study. The power system network, diesel generation units, load and PVPP data are collected in detail. And the one-line diagram of the study system with regarding peak and off-peak loading is set up in the simulation software for the steady state load flow analysis. After that, the transient stability analysis is executed with considering the tripping and power variation of various PVPP ramp rates with and without considering the over frequency compensation of photovoltaic (PV) inverters. The dynamic response of diesel generators and system frequency are examined carefully. It is found that the over frequency phenomenon can be controlled effectively by the regulation of PV inverters to achieve better reliability of the microgrid. [ABSTRACT FROM AUTHOR]

This article presents the electrical power planning, tests and analysis for a micro-grid (MG) in the distribution system. The MG of the Institute of Nuclear Energy Research has been selected for study. To enhance the MG reliability, two power sources are used for connecting to the utility power grid. The two power sources are currently interlocked, one for the regular and the other for the standby. Firstly, the phase sequence tests of the two power sources were performed to avoid the failure and damage of the equipment during power transfer. After that, the control logic planning between the two power sources is done to maintain the power supply of the MG. Finally, the reliability analysis for the load in the MG is performed to examine the effectiveness of the two power sources configuration. [ABSTRACT FROM AUTHOR]

This paper presents the effectiveness of the particle swarm optimization (PSO) to minimize the total active power loss of an island scale micro grid distribution network. In the adopted method, the co-simulation of the PSO algorithm and the Mat-power software on an island scale electrical network was proposed. The power system in Kiribati is selected as the study case. Two diesel power generation stations, one voltage regulator unit and one switching shunt capacitor bank are used to regulate the system voltage. The 24-h load flow is executed with the proposed PSO algorithm to minimize the active power loss and the annual power loss savings can be estimated. It is concluded that the proposed PSO algorithm can work well and give a satisfactory result. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) thermal resistance analysis provides a rapid and simple method to estimate the power generated from a waste heat recovery system with thermoelectric generators (TEGs), and facilitates an optimization of the system. Such a system comprises three parts – a waste heat recovery chamber, TEG modules and a cooling system. A fin-structured duct serves as a waste heat recovery chamber, which is attached to the hot sides of the TEGs; the cold sides of the TEGs are attached to a cooling system. The waste heat recovery chamber harvests energy from exhaust heat that the TEGs convert into electricity. The estimation of generated power is an important part of the system design. Methods of Computational Fluid Dynamics (CFD) assist the analysis and improve the performance with great accuracy but great computational duration. The use of this method saves much time relative to such CFD methods. In 3D thermal resistance analysis, a node of unknown temperature is located at the centroid of each cell into which the system is divided. The relations of unknown temperatures at the cells are based on the energy conservation and the definition of thermal resistance. The temperatures of inlet waste hot gas and ambient fluid are known. With these boundary conditions, the unknown temperatures in the system are solved, enabling estimation of the power generated with TEGs. A 3D model of the system was simulated with FloTHERM; its numerical solution matched the solution of the 3D thermal resistance analysis within 6%. The power generated with the same system with TEGs (TMH400302055, Wise Life Technology, Taiwan) was measured; the experimental result is consistent with the result obtained from the 3D thermal resistance analysis; the relative deviation is approximately 10%. The power generated is affected by many variables; the positions of the TEGs, the uniformity of the internal flow of the velocity profile and the internal and external flow velocities are considered in our 3D thermal resistance analysis. According to the results, both the positions of the TEGs and the uniformity of the internal flow of the velocity profile should be taken into account to maximize the power generation. Under varied operational conditions, the power generated from the system might be more sensitive to the velocity of either the internal or external flow. Choosing an appropriate method makes increasing the power generation efficient. The relations between variables and power generation are readily revealed, even with varied parameters, yielding an optimal design of a waste heat recovery system. [ABSTRACT FROM AUTHOR]

This paper investigates the impacts of a large wind power generation system (WPGS) on the distribution system. The installation of various types of distributed generators (DGs) on the distribution system will significantly affect the operating, planning and maintaining strategies of the utility. In this paper, one practical distribution system of Taiwan Power Company (Taipower) is selected for study. Various power quality issues like steady state voltage variation ratio, reverse power, flicker, short-circuit current as well as harmonic are investigated and calculated by applying the computer program simulation and the simplified calculation methods suggested by the International Electrotechnical Commission (IEC). The results will be compared with the Taipower relative standards to demonstrate the feasibility of the WPGS to be installed in the distribution feeder. [ABSTRACT FROM AUTHOR]

This paper presents the three-phase voltage and unbalance analysis for the distribution systemwith the loading of a light rail transit (LRT) tram. To investigate the dynamic responses of the system voltage and current, this paper adopts the Alternative Transients Program(ATP) software tomodel and simulate amultigrounded four-wire distribution system with an LRT loading. Two different definitions about unbalance are used to evaluate the problem. In this paper, the traction supply substation (TSS) with a singlephase transformer configuration is designed first for providing the electric power to the trams of LRT. However, itmay result in the significant neutral line current and unbalance phenomenon to deteriorate the power quality of the distribution system. A Le-Blanc connection transformer in the TSS is therefore proposed to solve the problems. [ABSTRACT FROM AUTHOR]

Abstract: This article proposes a concept of “effective Seebeck coefficient”, which discusses the inconsistency between the theoretical Seebeck coefficient and the measured one. The inconsistency can be explained via contact effect and thermal resistor network. Two different clamping forces are applied to the TEG module to observe the contact effect. Throughout the experiments, the electric resistance seems insensitive to the clamping force; somehow the thermal contact effect dominates the TEG module performance. In addition, a thermal resistor network, which is used to calculate the exact temperature difference traverse the TE ingot, has been constructed. After applying a suitable clamping pressure and modifying the actual ΔT with thermal resistor network, the “effective Seebeck coefficient” has been proposed. Notably, this proposed value is very helpful for better understanding characteristics of the behavior of the TEG module operating in the actual conditions we provided, and it can be used to predict the performance of the TEG module under any other condition. [Copyright &y& Elsevier]

Abstract: This paper presents the design of adaptive load-shedding strategy by executing the artificial neural network (ANN) and transient stability analysis for an Industrial cogeneration facility. ► To prepare the training data set for ANN, the transient stability analysis has been performed to solve the minimum load shedding for various operation scenarios without causing tripping problem of cogeneration units. Various training algorithms have been adopted and incorporated into the back-propagation learning algorithm for the feed-forward neural networks. ► By selecting the total power generation, total load demand and frequency decay rate as the input neurons of the ANN, the minimum amount of load shedding is determined to maintain the stability of power system. ► To demonstrate the effectiveness of the ANN minimum load-shedding scheme, the traditional method and the present load shedding schemes of the selected cogeneration system are also applied for comparison and verification of the proposed methodology. [Copyright &y& Elsevier]

This paper presents the electric power system analysis and design of an expanding steel cogeneration plant. The site and capacity of shunt capacitor banks as well as the tap position of transformers are determined according to the power flow analysis. Also, to comply with the restriction of circuit breaker capacity, the high-impedance transformers are designed. In addition, the voltage fluctuation resulted from the dramatic reactive power variation of hot strip rolling mill can be greatly reduced if proper static var compensator is installed. The significant voltage sag due to the starting of induction motor can be effectively improved by applying wye–delta transformer starter. Furthermore, the total voltage harmonic distortion and the total current demand distortion are both acceptable if the proper filters are installed. It is also found that the cogeneration system can keep stable operation in autonomous mode by applying the governor control action and the load-shedding scheme after tie line tripping. It is concluded that the power system analyses are important for the steel plant with cogeneration unit to identify hidden problems and remedy strategy to ensure the system power quality and operation performance. [ABSTRACT FROM AUTHOR]

Abstract: In this case study, a system to recover waste heat comprised 24 thermoelectric generators (TEG) to convert heat from the exhaust pipe of an automobile to electrical energy has been constructed. Simulations and experiments for the thermoelectric module in this system are undertaken to assess the feasibility of these applications. A slopping block is designed on the basis of simulation results to uniform the interior thermal field that improves the performance of TEG modules. Besides simulations, the system is designed and assembled. Measurements followed the connection of the system to the middle of an exhaust pipe. Open circuit voltage and maximum power output of the system are characterized as a function of temperature difference. Through these simulations and experiments, the power generated with a commercial TEG module is presented. Overview this case study and our previous work, the results establish the fundamental development of low-temperature waste heat thermoelectric generator system that enhances the TEG efficiency for vehicles. [Copyright &y& Elsevier]

This article presents the innovative control scheme of renewable ancillary services to support the system operation of a bulk power system with high penetration of renewable energy. The smart inverters of PV systems can be controlled to adjust the renewable generation of real and reactive power according to the variation of system voltage and frequency. The dispatch control of renewable ancillary services is integrated with the energy management system to achieve the coordination control of renewable energy and synchronous generators. The sensitivity factors of renewable system was applied to determine the generation curtailment for the mitigation of line overloading. The ancillary service of reactive power compensation by renewable energy was considered to improve the system voltage quality. The emergency generation control of renewable systems with fast ramping up capability was applied to illustrate the effectiveness of renewable ancillary service to improve the system frequency response after sudden generator tripping. Based on the computer simulation of an actual power system with large renewable energy to be integrated, the functions of virtual synchronous generators by the photovoltaic systems and wind farms have to be applied to ensure the successful steady-state operation and to improve the system transient stability for severe disturbance contingency. [ABSTRACT FROM AUTHOR]

Background and Aim: The serial serologic changes of hepatitis D virus (HDV) infection among chronic hepatitis B virus (HBV) infected patients who received oral nucleotide/nucleoside analogues are elusive. Methods: Serum anti‐HDV and HDV RNA among chronic hepatitis B (CHB) patients were tested at the time of initiating anti‐HBV therapy and subsequently during the follow‐up period. Results: The seropositive rate of anti‐HDV and HDV RNA among 2850 CHB patients, was 2.7% and 0.9%, respectively. Factors associated with anti‐HDV seropositivity were platelet counts (odds ratio [OR]/95% confidence intervals [CI]: 0.995/0.992–0.999; P = 0.006), HBV DNA levels (OR/CI: 0.81/0.70–0.94; P = 0.005), and hepatitis B e‐antigen (HBeAg) seropositivity (OR/CI: 0.22/0.05–0.95; P = 0.04). The only factor associated with HDV RNA positivity among anti‐HDV seropositive patients was age (OR/CI: 0.95/0.90–1.00; P = 0.03). The spontaneous clearance rate of serum anti‐HDV antibody was 3.0 per 100 person‐years with a median follow‐up period of 3.5 years (range 2–12 years), whereas the seroclearance rate of HDV RNA was 4.3 per 100 person‐years among anti‐HDV seropositive patients after a median follow‐up period of 6.0 years (range 2–11 years). A baseline anti‐HDV titer < 0.5 cut‐off index was the only factor predictive of anti‐HDV seroclearance (hazard ratio [HR]/CI: 30.11/3.73–242.85; P = 0.001). Conclusions: HDV infection was not common among patients treated for HBV in Taiwan. Seroclearance of anti‐HDV and HDV RNA did occur over time, albeit the chance is rare. [ABSTRACT FROM AUTHOR]

Background and Aims: Regorafenib has demonstrated its survival benefit for unresectable hepatocellular carcinoma (uHCC) patients in a phase III clinical trial. We aimed to assess the efficacy and tolerability of regorafenib and the predictors of treatment outcomes in Taiwanese patients. Methods: We analyzed the survival, best overall response, predictors of treatment outcomes, and safety for uHCC patients who had tumor progression on sorafenib therapy and received regorafenib as salvage therapy between March 2018 and November 2020. Results: Eighty‐six patients with uHCC were enrolled (median age, 66.5 years; 76.7% male). The median regorafenib treatment duration was 4.0 months (95% confidence interval [CI], 3.6–4.6). The most frequently reported adverse events were hand‐foot skin reaction (44.2%), diarrhea (36.0%), and fatigue (29.1%). No unpredictable toxicity was observed during treatment. The median overall survival (OS) with regorafenib was 12.4 months (95% CI, 7.8–17.0) and the median progression‐free survival (PFS) was 4.2 months (95% CI, 3.7–4.7). Of 82 patients with regorafenib responses assessable, 4 patients (4.9%) achieved a partial response, and 33 (40.2%) had stable disease, leading to a disease control rate (DCR) of 45.1% (n = 37). Patients possessing baseline AFP < 400 ng/ml exhibited a markedly longer median OS, median PFS, and higher DCR compared with their counterparts (15.7 vs. 8.1 months, 4.6 vs. 3.7 months, 60.9% vs. 27.5%, respectively). Despite possessing high baseline AFP levels, patients with early AFP response (>10% reduction at 4 weeks or >20% reduction at 8 weeks after regorafenib administration) exhibited comparable treatment outcomes to those with baseline AFP < 400 ng/ml. Conclusions: The results of this real‐world study verified the tolerability and efficacy of regorafenib treatment for uHCC patients who failed prior sorafenib therapy, especially for those with lower baseline AFP levels or with early AFP response. [ABSTRACT FROM AUTHOR]

Background and Aim: Hepatitis B virus (HBV) surface antigen (HBsAg) seroreversion usually occurs during immunosuppressive therapy. The risk and factors of HBsAg seroreversion from resolved HBV infection in the general population remained unclear. Methods: This retrospective study enrolled subjects with resolved HBV infection and who had received at least two times of screening in a longitudinal community screening program. HBsAg, hepatitis B surface antibody (anti‐HBs), and hepatitis C virus antibody (anti‐HCV) were tested every time in all subjects. The primary endpoint was HBsAg seroreversion. Results: Of the 7630 subjects enrolled, 5158 (67.6%) subjects had positive anti‐HBs at baseline. HBsAg seroreversion occurred in 84 subjects during 42 815‐person‐year follow‐up with an annual incidence of 0.2% and a 10‐year cumulative risk of 1.9%. Anti‐HBV treatment‐experienced subjects had a significantly higher risk of HBsAg seroreversion than anti‐HBV treatment‐naive subjects (83/310 [26.8%] vs 1/7320 [0.01%], P < 0.001). Lower rates of positive anti‐HBs and anti‐HCV were observed in anti‐HBV treatment‐experienced subjects who developed HBsAg seroreversion. Both positive anti‐HBs (hazard ratio/95% confidence interval: 0.56/0.348–0.903, P = 0.017) and positive anti‐HCV (hazard ratio/95% confidence interval: 0.08/0.030–0.234, P < 0.001) were independent factors of HBsAg seroreversion in anti‐HBV treatment‐experienced subjects. Less than 5% of the HBsAg seroreverters had clinical hepatitis flare at HBsAg seroreversion. The HBsAg titer was low, and only transient reappeared in most of the HBsAg seroreverters. Conclusions: Subjects with resolved HBV infection were at a minimal risk of HBsAg seroreversion, unless with prior anti‐HBV treatment experience. Fortunately, even with a reappearance of HBsAg, it was transient and clinically non‐relevant. [ABSTRACT FROM AUTHOR]

Background and Aim: Hemodialysis patients are at increased risk of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. Both HBV and HCV infections lead to risks of end‐stage liver diseases and extrahepatic manifestations. This study aimed to investigate hepatic and extrahepatic comorbidities in hemodialysis patients with HBV or HCV infections compared with those without viral hepatitis. Methods: A total of 1910 hemodialysis patients, including 159 HCV viremic patients (HCV group), 217 seropositive for HBV surface antigen (HBsAg, HBV group) and 1534 seronegative for both anti‐HCV and HBsAg (non‐B and non‐C [NBNC] group), from 23 hemodialysis centers were enrolled. Comorbidities were classified into 10 categories by the International Classification of Diseases‐10th Revision. Results: Among the 1910 patients, the mean age was 64.6 years, and 52.7% were male patients. A total of 1834 (96%) patients had at least one comorbidity, and the mean number of comorbidities was 2.9 ± 1.5 per person. The three most common comorbidities were hypertension, diabetes, and ischemic heart diseases. The mean number of comorbidities per person was significantly higher in the HCV group (3.3 ± 1.7) than in the HBV (2.7 ± 1.5, P < 0.001) and NBNC groups (2.9 ± 1.5, P = 0.004), mainly due to the higher prevalence of ischemic heart disease, respiratory disorders, and mental/behavioral disorders. The HBV and NBNC groups exhibited comparable burdens of comorbidities. Conclusions: Hemodialysis patients had a high prevalence of multiple comorbidities. Hemodialysis patients with HCV exhibited a higher burden of comorbidities, especially ischemic heart diseases, respiratory disorders, and mental/behavioral disorders, than HBV and NBNC patients did. [ABSTRACT FROM AUTHOR]

Uraemic patients undergoing haemodialysis are at high risk of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. We aimed to evaluate the evolutionary seroprevalence of viral hepatitis and the gap in HCV care cascades in this special population by a large‐scale surveillance study in Taiwan. Uraemic patients on maintenance haemodialysis from 22 sites (FORMOSA‐LIKE group) in 2012 (n = 1,680) and 2019 (n = 2,326) were recruited for this study. The distributions and sequential changes of viral hepatitis markers were analysed. The prevalence of anti‐HCV antibody and hepatitis B surface antigen (HBsAg) seropositivity was 13.6% (316/2326) and 11.5% (267/2326), respectively, in 2019 compared with 17.3% (290/1680, P =.002) and 13.6% (229/1680, P =.046), respectively, in 2012. The HCV‐viremic rate among anti‐HCV‐seropositive patients was significantly lower in 2019 than in 2012 (56.3% [178/316] vs. 73.8% [214/290], P <.001). The HCV treatment rate increased from 2.3% (5/217) in 2012 to 21.7% (49/226) in 2019 (P <.001). In the sequential analysis of the 490 patients who participated in both screens, 17 of the 55 HCV‐viremic patients became HCV RNA seronegative, including 13 by antivirals and four spontaneously. By contrast, one anti‐HCV‐seropositive but nonviremic patient became viremic, and six anti‐HCV‐seronegative patients became anti‐HCV‐seropositive in 2019. The annual incidence of new HCV was 0.2%/year. Seven HBsAg‐seropositive patients experienced HBsAg loss (1.25%/year). Two patients had new anti‐HBc seropositivity (new HBV exposure: 0.57%/year). The seroprevalence of viral hepatitis decreased in an 8‐year follow‐up but remained prevalent, and the treatment of HCV infection was underutilized in uraemic patients. Additional efforts are needed to enhance the HCV treatment uptake of uraemic patients. Clinical Trial IDs: NCT03803410, NCT01766895. [ABSTRACT FROM AUTHOR]

The spreading of viral hepatitis among injecting drug users (IDU) is an emerging public health concern. This study explored the prevalence and the risks of hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis D virus (HDV) among IDU-dominant prisoners in Taiwan. HBV surface antigen (HBsAg), antibodies to HCV (anti-HCV) and HDV (anti-HDV), viral load and HCV genotypes were measured in 1137(67.0%) of 1697 prisoners. 89.2% of participants were IDUs and none had HIV infection. The prevalence of HBsAg, anti-HCV, dual HBsAg/anti-HCV, HBsAg/anti-HDV, and triple HBsAg/anti-HCV/anti-HDV was 13.6%, 34.8%, 4.9%, 3.4%, and 2.8%, respectively. HBV viremia rate was significantly lower in HBV/HCV-coinfected than HBV mono-infected subjects (66.1% versus 89.9%, adjusted odds ratio/95% confidence intervals [aOR/CI] = 0.27/0.10–0.73). 47.5% anti-HCV-seropositive subjects (n = 396) were non-viremic, including 23.2% subjects were antivirals-induced. The predominant HCV genotypes were genotype 6(40.9%), 1a(24.0%) and 3(11.1%). HBsAg seropositivity was negatively correlated with HCV viremia among the treatment naïve HCV subjects (44.7% versus 72.4%, aOR/CI = 0.27/0.13–0.58). Anti-HCV seropositivity significantly increased the risk of anti-HDV-seropositivity among HBsAg carriers (57.1% versus 7.1%, aOR/CI = 15.73/6.04–40.96). In conclusion, IUDs remain as reservoirs for multiple hepatitis viruses infection among HIV-uninfected prisoners in Taiwan. HCV infection increased the risk of HDV infection but suppressed HBV replication in HBsAg carriers. An effective strategy is mandatory to control the epidemic in this high-risk group. [ABSTRACT FROM AUTHOR]

Hepatitis D virus (HDV) infection increases the risk of hepatocellular carcinoma (HCC) in the natural course of chronic hepatitis B (CHB) patients. Its role in patients treated with nucleotide/nucleoside analogues (NAs) is unclear. We aimed to study the role of hepatitis D in the development of HCC in CHB patients treated with NAs. Altogether, 1349 CHB patients treated with NAs were tested for anti-HDV antibody and RNA. The incidence and risk factors of HCC development were analyzed. Rates of anti-HDV and HDV RNA positivity were 2.3% and 1.0%, respectively. The annual incidence of HCC was 1.4 per 100 person-years after a follow-up period of over 5409.5 person-years. The strongest factor association with HCC development was liver cirrhosis (hazard ratio [HR]/95% confidence interval [CI] 9.98/5.11–19.46, P < 0.001), followed by HDV RNA positivity (HR/ CI 5.73/1.35–24.29, P = 0.02), age > 50 years old (HR/CI 3.64/2.03–6.54, P < 0.001), male gender (HR/CI 2.69/1.29–5.60, P: 0.01), and body mass index (BMI, HR/CI 1.11/1.03–1.18, P = 0.004). The 5-year cumulative incidence of HCC was 7.3% for patients with HDV RNA negativity compared to that of 22.2% for patients with HDV RNA positivity (P = 0.01). In the subgroup of cirrhotic patients, the factors associated with HCC development were HDV RNA positivity (HR/CI 4.45/1.04–19.09, P = 0.04) and BMI (HR/CI 1.11/1.03–1.19, P = 0.01). HDV viremia played a crucial role in HCC development in CHB patients who underwent NA therapy. [ABSTRACT FROM AUTHOR]

This article proposes a fault identification method that is embedded in an asset management system (AMS) to identify the faulted location based on the fault flags reported from the fault indicators (FIs). The fault identification model based on the Petri-net technology is developed using the distribution network topology generated by a geographic information system. The proposed method uses the data set of fault flags generated by FIs, the statuses of circuit breakers, the available precurrent and postcurrent measurements of FIs, and the loadings of distribution feeders and laterals. The hybrid communication system is applied to provide two-way communication between the control center and FIs. The AMS with the embedded fault identification method can dispatch the repair crews to the fault location faster to accelerate the customer service restoration. A distribution feeder of Taiwan Power Company was selected for the computer simulation to demonstrate the effectiveness of the proposed method by using the communication-capable FIs to identify the exact fault location of distribution lines after a short circuit fault occurs in a distribution system. [ABSTRACT FROM AUTHOR]

Background/Aims: Undetectable HCV RNA 12 weeks after the end of treatment (SVR12) has been the valid efficacy endpoint in the era of direct-acting antivirals (DAAs). Its concordance with SVR4 and SVR24 and long-term durability is unknown in Taiwanese chronic hepatitis C (CHC) patients. Methods: A total of 1080 CHC patients who received all-oral DAAs and an achieved end-of-treatment virological response (EOTVR), defined as undetectable HCV RNA at the end of therapy, were consecutively enrolled. HCV RNA was monitored 4, 12, and 24 weeks after EOT. Patients who achieved SVR24, defined as undetectable HCV RNA 24 weeks after EOT, were followed annually for assessing SVR durability. Results: Eleven (1.02%) patients experienced HCV RNA reappearance after EOT. The most frequent timing of RNA reappearance was observed at SVR4 (n = 7), followed by SVR12 (n = 3) and SVR 24 (n = 1). The positive predictive value (PPV) and negative predictive value (NPV) of SVR4 in predicting SVR12 were 99.7% and 100%, respectively, whereas the PPV and NPV of SVR12 in predicting SVR24 were 99.9% and 100%, respectively. Pyrosequencing confirmed delayed relapse rather than reinfection for the patient who had detectable HCV RNA at SVR24. Among 978 patients who achieved SVR24, after a median follow-up period of 17.3±8.2 months, the SVR durability is 100% up to a 4-year follow-up. Conclusion: Achievement of SVR12 provides excellent durability of HCV seroclearance after DAA therapy. On-demand HCV RNA beyond SVR12 should be recommended for patients with unexplainable abnormal liver function or high-risk behaviors. [ABSTRACT FROM AUTHOR]

To enhance the outage quality of a distribution system with a high penetration of photovoltaic (PV) renewable energy, this paper proposes a coordinating control strategy for an on-load tap changer (OLTC) of the main transformer in a distribution substation and PV smart inverters. The voltages at the end points of all distribution feeders that are served by the main transformer and the power generation of each PV system are collected using a SCADA system. The hourly tap position of the OLTC is then derived from the daily profiles of feeder voltage and the injected power that is generated by all PV systems along the feeder. Thereafter, the PV smart inverters perform autonomous control of reactive power compensation so that the voltage at the point of common coupling can be fixed at the specified voltage level. To demonstrate the effectiveness of the proposed voltage-control strategy, a main transformer, which serves six feeders of the Taiwan Power Company(Taipower) with high PV penetration, was considered in a case study. The proposed coordinating control of the OLTC and PV smart inverters dramatically improved the voltage quality of the distribution feeder and enabled the effective mitigation of the impact of large PV integration in the distribution system. [ABSTRACT FROM AUTHOR]

This paper proposes an innovative transformer management system (TMS) for energy control of customer loads and photovoltaic (PV) systems to solve the problems of transformer overloading and overvoltage due to power injection by PV renewable energy. The operation status of distribution transformers is monitored by transformer terminal unit (TTU) and reported to the control master station via the hybrid communication system. The demand response of customer load control is activated to reduce the loading level of transformers for mitigation of overloading problem. For the residential customers with installation of roof top PV system, the TTU is applied to perform the power factor control of smart inverter to prevent the overvoltage problem. The hybrid communication system consisting of power line carrier, LoRa radio frequency, and optical fiber is used to provide two-way communication for data collection and controls of customer loads and PV system. According to the field testing of the proposed TMS in Taiwan Power Company, the adaptive energy control of customer loads by TTU is executed when the overloading problem of distribution transformer occurs. The TTU also performs the power factor control of PV smart inverters to solve the overvoltage problem due to too much of PV power being injected during the solar peak period. The overvoltage problem due to PV power injection has also been solved by TTU for control of PV smart inverters to perform the proper reactive power compensation. [ABSTRACT FROM AUTHOR]

This study develops a renewable energy management system (REMS) for the control of photovoltaic (PV) smart inverters to mitigate the voltage violation of distribution systems with high penetration of PV installation. The impact analysis of distribution feeders with the PV system integration for decision making of smart inverter control has been embedded in REMS to solve the voltage violation problem. To verify the effectiveness of the proposed REMS to enhance the system voltage quality, a PV system installed in a distribution feeder of Taiwan Power Company (Taipower) has been selected for field testing. The real power, reactive power, and voltage of the studied PV system have been collected. The impact analysis of PV integration is performed to solve the mitigation of voltage variation by the control of reactive power compensation of smart inverters. It is found that the voltage at the test PV system is very consistent with the field test results. The computer simulation of a distribution feeder with a large PV farm has been executed to illustrate that the control of smart inverters can enhance the utilization of solar energy by reducing the curtailment of renewable power generation dramatically for a distribution system with high penetration of PV systems. [ABSTRACT FROM PUBLISHER]

An intelligent load-shedding strategy was designed and embedded in the special protection system (SPS) to enhance the system stability for an offshore island with high penetration of photovoltaic (PV) systems. To prepare the training dataset for the artificial neural network (ANN), the transient stability analysis of the isolated power system was executed to determine the minimum amount of load to be interrupted to prevent the tripping of diesel generators for the emergency shutdown of PV systems. By selecting various combinations of PV penetration levels, total system load demand, and the frequency decay rate at the instant of PV system tripping as the input neurons of the ANN, the proper load-shedding scheme is derived and stored in the decision knowledge base of the SPS. When the intelligent energy management system detects the tripping of a PV system, the SPS will be triggered to determine the amount of loss to be disconnected and executes the corresponding load interruption. By applying the proposed ANN-based load-shedding scheme in SPS, the amount of customer loading to be interrupted has been reduced dramatically for the restoration of system stability after the emergency shutdown of high-penetration PV system. [ABSTRACT FROM PUBLISHER]

This paper presents the dispatch of reactive power compensation and real power curtailment of photovoltaic (PV) systems to prevent the overvoltage violation when load transfer between distribution feeders is executed. The voltage sensitivity factors of reactive power injection at all PV buses are derived according to the configuration of the distribution network. The advanced distribution automation system issues the control command to each PV inverter for adjustment of PV power generation, according to the sensitivity coefficients and PV installation capacity, so that the ancillary service of voltage support can be provided by all PV systems in a fairer manner. The practical Taiwan Power Company (Taipower) distribution feeders are selected for computer simulation, to verify the effectiveness of the proposed control method to mitigate the voltage violation problem for the operation of load transfer between distribution feeders with high penetration of PV installation. [ABSTRACT FROM AUTHOR]

This paper presents a method for an adaptive relay setting for distribution systems with wind generators (WGs). The advanced distribution automation system (ADAS) is applied to monitor the operational status of WGs and line switches. For the change of operational status of WGs or network reconfiguration of distribution systems because of the operation of line switches, the function of the adaptive relay setting is activated by the ADAS control master station. Short-circuit analysis is performed to solve the magnitude and direction of fault-current flows. The protective relay settings are then accordingly revised and loaded to the protective relays along the feeder to achieve the adaptive fault protection. Sample distribution feeders with open- and closed-loop configurations are used to demonstrate the adaptive relay setting for distribution systems with various operational scenarios of WGs. It is concluded that the fault currents contributed by WGs must be included in the design of the tap/level settings of protective relays by the ADAS to achieve good protection of smart distribution systems. [ABSTRACT FROM PUBLISHER]

The PV penetration level of a distribution system is often limited by the violation of voltage variation caused by large intermittent power generation. This study investigates the use of a distribution static compensator (DSTATCOM) in reactive power compensation for system voltage control, during peak solar irradiation, in order to increase the PV installation capacity of a distribution feeder and avoid the voltage violation problem. PV power generation is simulated using hourly solar irradiation and temperature data provided by the weather bureau. The voltage variation at the point of common coupling (PCC) is also derived by executing the 3-\varphi load flow analysis to determine the maximum PV power injection without causing voltage violation. By applying the proposed voltage control scheme of DSTATCOM during high solar irradiation periods, the total power generation and the total energy delivered by the PV system over one year are determined according to the annual duration of solar irradiation. The annual sales of PV power, the system O&M cost, the cost of DSTATCOM installation and the initial capital investment for a PV system are then used to calculate the cash flow over the system life-cycle and the final net present value (NPV) of the PV project. With the proposed DSTATCOM voltage control to perform reactive power compensation, the optimal installation capacity of PV systems can be determined by maximizing the net present value of the system to ensure the best cost-effectiveness of the PV project and to better utilize solar energy. [ABSTRACT FROM PUBLISHER]

To promote the photovoltaic (PV) installation, a large-scale PV system installed in the Main Stadium of the 2009 World Games has been investigated for the design of selling price of PV power generation. The PV power generation is simulated according to the hourly solar irradiation and temperature provided by the weather bureau. The cash flow of annual power generation, the O&M cost, and the capital investment cost of the PV system is then used to derive the payback years and the internal rate of return for the PV system under different selling price of PV power generation. The voltage variation and the power system loss of the distribution feeder, which serves the Main Stadium, are also performed by executing the 3-\varphi load flow analysis for the impact analysis of the PV system. The results indicate that the reduction of voltage drop and power system loss can be obtained with the PV system installed to provide the dispersed generation for the local loads. However, the PV system penetration is limited due to the violation of voltage variation introduced by the large intermittent PV power generation. The selling price of PV generation has to be designed according to the conditions of solar irradiation and temperature so that sufficient incentives can be provided to encourage more customers to participate the PV program. [ABSTRACT FROM AUTHOR]