A Regulating Capacity Determination Method for Pumped Storage Hydropower to Restrain PV Generation Fluctuations

The variable speed and constant frequency pumped storage hydropower(PSH)unit can strongly support the complementation and joint power supply of cascaded hydropower and photovoltaic(PV)plants.Its fast response capability has provided a feasible solution for the rapid power and voltage regulation caused by real-time fluctuations of PV systems.However,currently there is a lack of research on precise evaluation on regulation capability and regulating capacity configuration for PSH to restrain the real-time fluctuations.In this paper,a cascaded hydro-PV-PSH complementary joint power system(CHPP)is studied,and a“rule-based”method for regulating capacity determination is proposed.A combined statistical technique is introduced to analyze the initial estimated regulating capacity of PSH.A continuous cyclic revision method is adopted to renew the ideal PV curve by repeatedly using the main operating constraints until an optimal regulating capacity of PSH matching the PV generation scale is achieved.The results of the case study verified the feasibility and effectiveness of PSH for restraining the fast fluctuations of PV systems in real-time,and the configuration between PV and PSH regulating capacity is obtained with real-time application requirements.Finally,analyses including weather conditions,curtailed energy and electricity shortage,the sensitivity analysis,and state transition frequency are presented to demonstrate the robustness of this study.

Valve Dynamic and Thermal Cycle Model in Stepless Capacity Regulation for Reciprocating Compressor

The existing researches of stepless capacity regulation system by depressing the suction valve for reciprocation compressor always adopt hypothesis that the compressor valves are open or close instantaneously, the valve dynamic has not been taken account into thermal cycle computation, the influence of capacity regulation system on suction valves dynamic performance and cylinder thermal cycle operation has not been considered. This paper focuses on theoretical and experimental analysis of the valve dynamic and thermal cycle for reciprocating compressor in the situation of stepless capacity regulation. The valve dynamics equation, gas forces for normal and back flow, and the cylinder pressure varying with suction valve unloader moment during compression thermal cycle are discussed. A new valve dynamic model based on L-K real gas state equation for reciprocating compressor is first deduced to reduce the calculation errors induced by the ideal gas state equation. The variations of valve dynamic and cylinder pressure during part of compression stroke are calculated numerically. The calculation results reveal the non-normal thermal cycle and operation condition of compressor in stepless capacity regulation situation. The numerical simulation results of the valve dynamic and thermal cycle parameters are also verified by the stepless capacity regulation experiments in the type of 3L-10/8 reciprocating compressor. The experimental results agree with the numerical simulation results, which show that the theoretical models proposed are effective and high-precision. The proposed theoretical models build the theoretical foundation to design the real stepless capacity regulation system.

Impact of the Three Gorges Dam on Regulation and Storage Capacity of Poyang Lake

The regulation and storage capacity of Poyang Lake is infl uenced by the fl ow from the main stream of the Yangtze River and the fi ve rivers in the Poyang Lake basin.After the operation of the Three Gorges Dam(TGD),hydrological changes in the main stream of the Yangtze River impact water exchange between the Yangtze River and Poyang Lake.Based on the analysis of measured data and factors infl uencing outfl ow at Hukou station,a new empirical formula describing outfl ow at Hukou station and critical water level for lake storage capacity is established.The change in monthly storage capacity of Poyang Lake before and after the construction of the TGD is analyzed quantitatively.The results show that the fl ows from the main stream of the Yangtze River and the fi ve rivers in the Poyang Lake basin affect outfl ow and water storage capacity by changing the water level difference between Xingzi and Hukou stations and by changing the water level at Hukou station.But the Yangtze River and the fi ve rivers in the Poyang Lake basin differ in process and degree.If the water level at Hukou station remains consistent,when the fl ow from the fi ver rivers increases by 1,000 m3/s,the outfl ow at Hukou station increases by 304 m3/s.When the fl ow from the main stream of the Yangtze River increases by 1,000 m3/s,the outfl ow at Hukou station decreases by 724 m3/s.In addition,the operation of the TGD affects the water storage capacity of Poyang Lake.The water volume of Poyang Lake decreases by 49.4%in September,but increases by 47.7%in May.

Dynamic discharging characteristics of absorption thermal battery under different capacity regulation strategies

Thermal battery plays an important role in renewable energy utilization towards carbon neutrality.The novel absorption thermal battery(ATB)has excellent performance but suffers from serious capacity attenuation.To address this problem,two capacity regulation methods,i.e.,variable solution flow and variable cooling water flow,are proposed to achieve a demanded discharging rate.The effects of the two regulation strategies on the dynamic discharging characteristics and overall storage performance are comparatively investigated.To demon-strate the adjustability of the output capacity,several stable discharging rates are successfully maintained by the proposed methods.To maintain a higher discharging rate,the stable discharging time has to be sacrificed.As the demanded output increased from 0.5 kW to 6.0 kW,the stable discharging time decreased from 781.8 min to 27.9 min under variable solution flow and from 769.9 min to 30.7 min under variable cooling water flow.With the increase of solution or water flow rate,the energy storage density is improved,while the energy storage efficiency is slightly increased first and decreased later.The regulation method of variable water flow shows relatively lower energy storage efficiency due to the larger pump power.This study could facilitate reasonable development and application of ATB cycles.

A One Health approach to fight antimicrobial resistance in Uganda: Implementation experience, results, and lessons learned

Uganda has been implementing the Global Health Security Agenda(GHSA)since 2015 to build its capacity according to World Health Organization(WHO)Benchmarks on International Health Regulations Capacities.The country remains prone to outbreaks,with more than 20 disease outbreaks reported in the past five years,including Ebola virus disease,Crimean-Congo haemorrhagic fever,Marburg haemorrhagic fever,measles,yellow fever,coronavirus disease 2019(COVID-19),and cholera.Antimicrobial resistance(AMR)is an ongoing challenge.Uganda scored capacity level 3 on infection prevention and control(IPC)and antimicrobial stewardship(AMS)in the 2017 Joint External Evaluation(JEE)assessment.Identified gaps were being addressed after a self-assessment in 2021.This paper describes the technical assistance approaches provided to Uganda by the Medicines,Technologies,and Pharmaceutical Services Program,funded by the United States(U.S.)Agency for International Development,and implemented by Management Sciences for Health.The program,through a One Health approach,supported systematic capacity strengthening based on the JEE's capacity advancement framework for global health security,specifically relating to AMR.The program's interventions impacted 32 WHO benchmark actions(7 for AMR multisectoral coordination,16 for IPC,and 9 for AMS),contributing to Uganda's strengthened GHSA capacity.Leveraging success built on the AMR platform,the program trained 745 health workers in IPC for the Ebola virus and provided support for simulation exercises by eight district IPC teams.The program also worked with the Ministry of Health to coordinate IPC for the COVID-19 response in five health regions,covering 45 districts and reaching 5,452 health workers at 858 health facilities.