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This paper proposes a novel data driven framework for detecting topology transitions in a distribution network. The framework analyzes data from phasor measurement units (PMUs) and relies on the fact that changes in network topology results in changes in the structure and admittance of the network. Using voltage and current phasors recorded by PMUs, the proposed method approximates network parameters using an ensemble-based deep learning model and thus, it does not require any knowledge of network parameters and load models. Using the prediction error of the proposed model, a connectivity matrix which shows the status of switches is constructed. In contrast to other methods, this proposed framework does not require a library of voltage and current transients associated with possible network transitions. It can also detect simultaneous switching actions and is robust to noise and load variations. The model yields a lower error detection rate, and its performance is validated using a modified version of the IEEE 33 bus network and a real feeder located in Queensland, Australia, under full and partial observability conditions. The proposed model has also been compared with another data driven method in terms of inference time and error detection rates. [ABSTRACT FROM AUTHOR]

Synchronous generators are operating for less time than before or being decommissioned in the National Electricity Market (NEM) of Australia, due to the proliferation of asynchronous wind and solar generation. Sub-networks of the NEM will face inertia shortages in the near future. This paper develops a formulation of zonal inertia constrained generator dispatch for power systems with a diversified generator portfolio including synchronous generators, synchronous condensers, inverter-interfaced generators and energy storages. Zonal inertia constraints are formulated in unit commitment and optimal power flow to limit the rate of change of frequency (RoCoF) in the event of network separation. Load frequency relief is also considered to reduce the ramp rate requirement of primary reserve. The proposed formulation can reduce the average cost of primary reserve and maintain zonal inertia adequacy to constrain RoCoF in case of the trip of the interconnector(s). [ABSTRACT FROM AUTHOR]

Particulate matter exposure has been described to elevate the risk of lung and cardiovascular diseases. An increasing number of recent studies have indicated positive correlations between PM 2.5 (the fraction of airborne particles with an aerodynamic diameter less than 2.5 μm) exposure and the risk of liver diseases. However, research on the effects of PM 2.5 exposure on liver fat synthesis, secretion, and clearance mechanisms under normal diet conditions is limited, and whether these effects are age-dependent is largely unknown. Female C57BL/6 mice at different ages (4 weeks (4 w), 4 months (4 m), and 10 months (10 m)) were treated with 3 mg/kg body weight of PM 2.5 every other day for 4 weeks. Subsequently, the ultrastructural changes of liver, the expression of genes involved in oxidative damage and lipid metabolism in the liver were examined. Observation of hepatic ultrastructure showed more and larger lipid droplets in the livers of 4-week-old and 10-month-old mice exposed to PM 2.5. Further analysis showed that PM 2.5 exposure increased the expression of genes related to lipid synthesis, but decreased the expression of genes involved in lipid transport and catabolism in the livers of 10-month-old mice. Our findings suggest that exposure to PM 2.5 disrupts the normal metabolism of liver lipids and induces lipid accumulation in the liver of female mice in an age-dependent manner, with older mice being more susceptible to PM 2.5. Image 1 [ABSTRACT FROM AUTHOR]

• Both current and voltage waveform data is required for abnormality detection. • The assumption of real-life data following Gaussian Distribution is too ideal. • The Direct Comparison method can enable real-time online condition monitoring. • Performance of the Direct Comparison method is superior than the other two methods. In recent years, high quality sensors and meters have enabled equipment condition monitoring. In comparison with power quality monitoring, which has been well-studied in the past three decades, equipment condition monitoring is a relatively new field that focuses on the identification of incipient faults or abnormal operations. In current literature, equipment condition monitoring is carried out through the abnormality detection of waveform-type disturbance data. However, most waveform abnormality detection methods focus on events associated with specific equipment, with only a few methods developed for generic detection. Generic detection is crucial when engineers have no knowledge of the exact equipment that is causing abnormal operations while monitoring a complex system, such as a substation. To this end, this paper summarizes the theories behind abnormality detection and develops three different generic methods in the process, namely the Direct Comparison method, the KLD method and the RSV method. It is proven in this paper that the KLD method and the RSV method are fundamentally inferior in performance compared to the Direct Comparison method due to their assumptions being too ideal. Finally, the Direct Comparison method is proved to be reliable in terms of detection rate and fast enough for online applications. [ABSTRACT FROM AUTHOR]

Abstract There are often multiple volume fracturing horizontal wells producing simultaneously in the tight oil reservoir. However, from the published literature, there are a large number of seepage models for a single volume fracturing horizontal well, and there are few literature on the transient pressure behavior of multiple horizontal wells. In order to simulate the actual production of multiple horizontal wells in the field, the seepage model of multiple horizontal wells was established in this paper. In this paper, transient pressure behavior model of multiple horizontal wells is composed of two parts. One is the seepage model of reservoir and the other is seepage model in the fracture network. Firstly, based on a new plane source function, by virtue of superimposing method, the seepage model of dual medium reservoir is established considering interference between fractures. Secondly, the fluid seepage model of the complex fracture network is established by using "star-triangle" transformation method. Finally, based on the continuity equation, the reservoir model and the fracture flow model are coupled to form a complete transient pressure behavior model for multiple volume fracturing horizontal wells. Using this model, we calculate the transient pressure behavior of multiple fracturing horizontal wells, and ten typical flow regimes are divided. The influences of some of the critical parameters on the transient pressure behavior were studied, including the distance between the multiple wells, storage ratio and cross flow coefficient et al. In a word, this paper provides a very useful model for reservoir engineers regarding evaluating the performance of multiple horizontal wells with complex fracture networks. Highlights • This paper establishes a transient pressure behavior model that can simulate multiple fractured horizontal wells. The model considers the influence of complex fracture network and interference between horizontal wells. • The process of fluid flow of multiple horizontal wells with complex fracture networks in tight oil reservoir can be divided into ten flow regimes: StageⅠfracture linear flow, StageⅡis bilinear flow, Stage Ⅲ is reservoir linear flow, Stage Ⅳ is first transition flow, StageⅤis fractures interference flow inside the complex fracture network, Stage Ⅵ is second transition flow, Stage Ⅶ is interference flow between the two wells, Stage Ⅷ is first radial flow, StageⅨ is cross flow, StageⅩ is pseudo-radial flow in the entire system. • In order to study the seepage characteristics of each flow regime more directly, we choose seven typical moments (t1∼t7) in Fig. 11 and give the dimensionless production of each fracture in 3D view (as shown in Fig. 12). [ABSTRACT FROM AUTHOR]

Over the last decade, many power systems have significantly changed with the proliferation of renewable generation sources, such as wind and solar photovoltaic. Due to their variability and nonsynchronous nature, new challenges and complexities have emerged regarding operational security of modern power systems. The 2016 South Australia (SA) blackout was the first known blackout due to such a high renewable situation. An official report has recently been published to review the causes and provide the corresponding recommendations for improvement of network operation, control, and security. However, there are still a number of critical issues and debates which remain unsolved, such as network bottleneck identification, overvoltage explanation, pole slip concern, frequency dip mystery, and frequency/voltage instability debate. In this paper, based on the reconstruction of the event, these unsettled issues are prudently analyzed to unveil their root causes. In addition, an innovative scheme is proposed to prevent the blackout by identifying the network separation at an early stage. This research will not only further advance the understanding of the 2016 SA blackout, but also will provide valuable guidelines for the management of future renewable-rich networks. [ABSTRACT FROM AUTHOR]

• Urbanized river had a higher sediment denitrification rate and N 2 O production. • Denitrification rate decreased with nitrate removal but its efficiency increased. • Warming offset the efforts of reducing river N 2 O production by pollution abatement. Global nitrogen (N) pollution has resulted in increased river nitrous oxide (N 2 O) emissions, which contribute to climate change. However, little is known about how pollution abatement conversely reduces river N 2 O production in a warming climate. Here, field observations and microcosmic experiments were conducted in a coastal urbanized watershed (S.E. China) to explore the interactive effect of changing nitrate and temperature on river sediment denitrification (DNF) and N 2 O production. The results showed that urban river reaches (UR) with higher organic carbon content and denitrifying gene abundance in sediments have a greater DNF rate, nitrate removal efficiency (NRE), and N 2 O concentration than agricultural river reaches (AR). Microcosmic incubation suggested that the DNF rate and associated N 2 O production decreased under low nitrate addition, wherein the NRE increased. The scenario simulation illustrated a nonlinear response of N 2 O production to nitrate removal (i.e., ΔN 2 O/ΔNO 3 -N) from both UR and AR sediments at a given temperature, and the DNF rate and N 2 O production increased with increasing temperature. An increase in temperature by 1 degree Celsius would offset 18.75% of the N 2 O reduction by nitrate removal via DNF. These findings implied that watershed pollution abatement undoubtedly contributes to the reduction in global river N 2 O emissions although it is partially offset by extra N 2 O production caused by global warming. [Display omitted] [ABSTRACT FROM AUTHOR]

With the rapid development of photovoltaic (PV) technology, more utility-scale PV systems are being integrated into rural areas where abundant and low-cost land is available. In these areas, step-voltage regulators (SVRs) with an open-delta configuration are widely used for voltage regulation. However, since SVRs were initially designed for tackling slow and smooth load variations, frequent PV output fluctuations can cause excessive tap changes. Moreover, rural communication facilities are normally expensive and underdeveloped, so only limited parameters are recorded with low resolution and reliability. Thus, much needed tap information cannot be properly monitored in a cost-effective way. In contrast, a downstream load center or utility-scale PV site is commonly well equipped with modern sensors and data acquisition systems, which provide the possibility for tap evaluation. Therefore, this paper proposes a new remote tap position estimation approach to accurately assess the upstream tap positions of open-delta SVRs from downstream measurements. Furthermore, the proposed approach is firmly validated through field testing under the support of the local utility and PV plant owner. This novel method not only enables reliable tap position monitoring with high precision for utilities to research PV–SVR interaction, but also provides valuable information to PV owners for correctly analyzing downstream voltage performance. [ABSTRACT FROM AUTHOR]

The installed capacity of wind generation and photovoltaics (PV) in many countries is going to dominate generation fleets in a bid to meet growing renewable energy targets. Synchronous inertia has never been problematic as there was more available than needed, but it is being significantly reduced due to the increasing integration of nonsynchronous renewable generation. When the low bidding priced generation of wind and PV becomes considerably large, conventional economic dispatch algorithms can result in less online synchronous inertia and put power system security at risk. However, the compromise of power system security due to synchronous inertia shortage is not well studied in the literature. This paper develops a synchronous inertia constrained economic dispatch algorithm to satisfy the minimum required synchronous inertia of frequency control. Synchronous condensers and wind reserve are economically allocated to alleviate any shortage of synchronous inertia and frequency control ancillary services (FCAS). A Gaussian particle swarm optimization algorithm is introduced to simultaneously co-optimize the dispatch of synchronous generators and their FCAS, wind reserve, and synchronous condensers. [ABSTRACT FROM AUTHOR]

Any mismatch between load and generation (due to a generator or an interconnection trip) is intended to be balanced and stabilized by contingency reserve, which is also known as contingency Frequency Control Ancillary Services (FCAS) requirement. Load Frequency Relief (LFR), which represents the effect of frequency dependent loads on power system frequency excursion, is crucial for correctly evaluating contingency reserve requirement during generation dispatch to ensure an adequate frequency response. Over estimation of LFR can be accountable for less planned reserve during an economic dispatch that may cause undesirable frequency performance. On the other hand, under estimation of LFR can result in an excessive reserve and hence could unnecessarily increase system operational cost. Conventionally, LFR is considered as a fixed quantity during the evaluation of FCAS requirement. However, recent experience in the Australian power grid suggests that such an assumption may lead to an inaccurate outcome. To explore the above issue, this research investigates the LFR using field measurement data, which were captured at different locations of the southern states of Australia (e.g., Tasmania and Victoria). An approach is developed to identify the predominating factors affecting the LFR and subsequently a technique is proposed to appropriately determine contingency FCAS requirement. [ABSTRACT FROM PUBLISHER]

Power system security concerns due to significant wind generation could be twofold: first, the frequency response and second, the short‐circuit performance. Continuous development of wind energy may cause economic replacement and retirement of existing synchronous generators. Modern wind turbine generators do not inherently offer inertia and governor response after a disturbance, which may result in declining frequency response behaviour. Besides, they have limited fault current contribution, which may cause unacceptable short‐circuit ratio at the grid connection point of those wind power plants. Traditionally, frequency response and short‐circuit performance are individually improved. However, both of them are concurrently affected by high wind penetration. Hence, a common approach to simultaneously enhance both indices is essential. Therefore, this study introduces an idea of operating some of the retired synchronous generators in the synchronous condenser mode, which is termed as 'post‐retirement scheme (PRS)'. Such a second use of the retired synchronous generators can jointly upgrade frequency response and short‐circuit strength during high wind generation. This study also proposes a methodology to evaluate when and how much PRS should be deployed for ensuring an adequate security performance in a wind dominated power system. [ABSTRACT FROM AUTHOR]

Renewable generations are growing fast and they are becoming the major generation technology in power systems. Amongst all renewables, wind and solar resources have the highest growth rate. However, fluctuation and uncertainty of these sources are the main barriers in their utilization and can affect reliability of power system. Therefore, these generators must be treated differently in adequacy studies and their reliability contribution should be evaluated. South Australia (SA) accounts for more than half of Australia's wind share and its solar capacity is rapidly increasing as well. Thus, not only the reliability benefit of wind is required to be investigated in this power system, but also the contribution of solar energy and its impacts should be analysed as well. The reliability benefit of wind and PV has been studied in the literature, but there is a need to evaluate their combined contribution in reality and investigate the influence of their correlations. Therefore, this paper evaluates the reliability contribution of wind and solar power in South Australia and the impact of solar energy on wind load carrying capability. State sampling Monte Carlo technique is utilized for reliability assessment and Fuzzy C-means clustering method is employed to create a multistep load model. [ABSTRACT FROM AUTHOR]

In many countries, it is common for medium voltage (MV) and low voltage (LV) to share the same pole and power line corridor, and this has been a general practice for decades. The MV line and the LV line separation distance may be short under some situations; therefore the mutual coupling may become substantial, which can have a significant impact on network voltages. In the literature, such coupling effect is generally ignored, and there is a lack of a detailed model of the coupled MV and LV lines for incorporation into load flow programs. This study develops a model for unbalanced distribution lines considering the mutual coupling between different voltage levels. Then the established model is utilised in a current injection load flow program to analyse the MV/LV coupling impacts on distribution system voltage. [ABSTRACT FROM AUTHOR]

Purpose: The study aims to perform a meta-analysis to compare the diagnostic value of FDG PET with PET/CT in detecting peritoneal carcinomatosis (PC) to identify the potentially most useful diagnostic modality.Methods: A computer-aided search was performed in the Cochrane Library, PubMed, EMBASE, Web of Science, the China Biological Medicine Database, VIP, China National Knowledge Infrastructure database, and Wanfang databases for articles concerning diagnosis of peritoneal metastases with PET or PET/CT. QUADAS was used to evaluate the included articles' quality.Results: On a per-patient basis, the pooled sensitivity of PET/CT (84%) was significantly higher than that of PET (60%), and the pooled specificity of PET (98%) was markedly higher than that for PET/CT (94%). On a per-lesion basis, the pooled sensitivity and specificity of PET/CT were 87 and 95%, respectively. Only 1 PET study on a per-lesion basis, its sensitivity is 65.8 and specificity is 94.1%.Conclusions: PET and PET/CT are powerful imaging techniques for detection and characterization of PC. PET/CT can be used as a screening tool and it may be acceptable to use PET as a diagnosis tool. [ABSTRACT FROM AUTHOR]

Wind energy is becoming a significant source of generation in many countries because of its zero fuel cost and no air pollution. Due to integration of large-scale wind power in conventional grids, synchronous generators are being economically replaced. Modern wind farms are based on power electronics interface; and unlike synchronous generators, they do not have inherent frequency support capability. So, in a combined synchronous and non-synchronous machine based power system, it has always been a concern for a network operator to maintain system frequency within acceptable limits following a major disturbance. From power system security point of view, wind penetration can be limited by frequency response criteria. Up to now, several methodologies have been proposed to estimate maximum threshold of wind integration. However, none of them recommends how a system operator could be immediately informed about a secured wind penetration limit, as soon as generation profile is known. This paper proposes a new estimation tool of maximum wind penetration level from the frequency response adequacy point of view. Available system information viz. inertia and headroom are used as input parameters in the developed tool. Output of this tool will provide the highest margin of wind power that can be integrated at a particular load condition without violating frequency response constraints. The proposed technique is applied and analysed for a 250 bus, 65 machine Australian electricity network. [ABSTRACT FROM AUTHOR]

To achieve clean energy targets, more renewable generators – mainly wind and photovoltaic (PV) – are being integrated into electricity networks. However, wind and PV are non-synchronous generators to the grid and they traditionally have neither enough inertia response nor governor support to control major frequency excursions under most situations. Currently in South Australia, the combined generation of wind and rooftop PV has nearly reached the level of average demand with minor support through interconnection import. In such a situation it is likely that there may be fewer synchronous machines online for frequency regulation. Under such a scenario, a contingency could produce a more severe frequency excursion, violating in place frequency standards. Further, many distributed PV systems in South Australia may have a default under-frequency protection setting, which could be higher than the under-frequency load shedding (UFLS) threshold. Hence, a moderate generation/import trip may cause a massive secondary PV trip, which may result in an unacceptably low frequency, triggering further load shedding. This will certainly have an adverse impact on network security. A similar issue of secondary PV trip is not restricted to South Australia and may occur in other regions and countries as well. In this paper, a network which loosely represents the Australian National Electricity Market (NEM) is selected and modified to investigate and analyze network frequency response under high non-synchronous machine penetration. This network contains all necessary models for a comprehensive frequency response study, such as synchronous machine, governor, stabilizer and wind generator. The relevant functions such as load frequency relief, PV tripping and load shedding which are essential for frequency response evaluation are established in the approved and well-accepted platform – PSS®E. The results show that low inertia and secondary PV tripping can become serious issues for network frequency regulation and in some situations they can even cause system oscillation and stability concerns. [ABSTRACT FROM AUTHOR]

Highlights: [•] This paper investigates the impacts of PV power variability on voltage regulation. [•] Quasi-Static Time-Series method and recorded yearlong data are used in this study. [•] It is found a small DSTATCOM can significantly reduce OLTC tap changes. [•] Consequently OLTC maintenance cost will decrease. [•] The proposed strategy can be used to evaluate solutions for voltage regulation. [ABSTRACT FROM AUTHOR]

Highlights: [•] PV performance is investigated by utilizing the yearlong recorded data from the PV systems at the University of Queensland. [•] The established theoretical model has good agreement with the field measurement. [•] The validated theoretical model is applied for performance prediction of PV systems in Brisbane, Australia. [ABSTRACT FROM AUTHOR]

In distribution power systems line transposition is not a common practice and phase loading levels are always changing. Therefore, perfect balance is never achieved at a distribution level. Non-transposed lines can cause unequal voltage drops between phases and this may be further exacerbated by uneven loads in each phase. Consequently, the voltage magnitude of a certain phase may suffer a severe decrease, breaching the lower voltage limit or unbalanced three-phase voltages at a remote bus may violate the percentage voltage imbalance accepted in the standards. This paper examines the mechanism of causing uneven voltage drops and investigates the impacts of unbalanced line configurations with different phase loading levels on network voltage imbalance. Methodologies are proposed to analyze voltage drops affected by line and load imbalance. Based on these methods, general guidelines are recommended to mitigate the voltage problems, which are useful for network analysis, planning and reconfiguration. [ABSTRACT FROM PUBLISHER]

• The proposed method can solve voltage issues and enable higher PV penetration. • PV imbalance makes traditional methods less effective on overvoltage mitigation. • A joint centralized-decentralized method is developed for unbalanced PV scenarios. • The new approach controls fast PV fluctuations in a coordinated and distributed way. Due to random connection of small-size single-phase rooftop photovoltaic (PV) generators in residential areas, low voltage distribution systems tend to have unbalanced PV integration across phases. In such situations, traditional reactive power compensation methods may cause unintended Voltage-Reactive Power responses across phases due to line coupling, which consequently affects their effectiveness on overvoltage mitigation. Such overvoltage problems significantly hinder the future integration of clean and renewable solar energy resources in power networks. In this paper, the limitations of traditional methods in PV imbalance scenarios are revealed and comprehensively analyzed by a voltage sensitivity method for the first time. On this basis, an innovative joint centralized-decentralized method is developed to overcome the PV imbalance-induced voltage regulation challenge. Specifically, the inverter's reactive power response to PV power variations in different phases is adaptively scheduled in order to avoid adverse effect of inter-phase Voltage-Reactive Power interaction on voltage regulation. The effectiveness of the proposed method is validated by time-series simulations with recorded data and a real-life low voltage distribution system in Australia. With the traditional method (i.e. power factor droop control strategy), 93 minutes' overvoltage can be observed in the case study, which will trigger overvoltage protection and disconnect PV inverters from the grid. While, the proposed method can always control the system voltage within the allowable range, and it consequently avoids PV disconnection. By solving this bottleneck issue, more PV systems can be integrated into distribution networks, which consequently contributes to CO 2 emission reduction in future. [ABSTRACT FROM AUTHOR]

This article proposes a novel algorithm employing space vector ellipse (SVE) in a complex plane to classify and visualize power quality disturbance-events (PQDEs). In the proposed method, at first, the time-domain signal and a reference signal, which are separated by 90°, are mapped in a complex 2D coordinates. Thus, the tip of resultant rotating vector traces an ellipse, from which three parameters, namely, semi-major axis, semi-minor axis and inclination angle, are obtained. Then, the ellipse parameters are exploited to classify and visualize nine types of PQDEs, namely, voltage sag, swell, interruption, harmonic, sag-harmonic, swell-harmonic, notch, flicker and transient. To validate the practicability of the proposed approach, an extensive real-time simulation study is carried out on RTDS platform using a test microgrid network to generate a large number of PQDEs. The test events were successfully classified and visualized in complex plane. Moreover, the noisy and practical signals, recorded by IEEE 1159.2 Working Group, were successfully classified to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

There are more large-scale photovoltaic (PV) plants being established in rural areas due to availability of low-priced land. However, distribution grids in such areas traditionally have feeders with low X/R ratios, which makes the independent reactive power compensation method less effective on voltage regulation. Consequently, upstream step voltage regulator (SVR) may suffer from excessive tap operations with PV-induced fast voltage fluctuations. Although a battery energy storage system (BESS) can successfully smooth PV generation, frequent charge/discharge will substantially affect its cost effectiveness. In this paper, a real-time method is designed to coordinate PV inverters and BESS for voltage regulation. To keep up with fast fluctuations of PV power, this method will be executed in each 5 s control cycle. In addition, charging/discharging power of BESS is adaptively retuned by an active adjustment method in order to avoid BESS premature energy exhaustion in a long run. Finally, through a voltage margin control scheme, the upstream SVR and downstream PV inverters and BESS are coordinated for voltage regulation without any communication. This research is validated via a real-time digital simulator MatLab cosimulation platform, and it will provide valuable insights and applicable strategies to both utilities and PV owners for large-scale PV farm integration into rural networks. [ABSTRACT FROM PUBLISHER]

• MACCDA-based method for revealing the coupling multifractal characteristics of SD. • WMFSI-based framework for generating synthetic fine granularity SD. • The results show reliability, efficiency and scalability of the proposed scheme. As one type of advanced sensor, Phasor Measurement Units (PMUs) provide network operators with high-precision time-series Synchrophasor Data (SD) which characterise the operational condition of power systems. Source information of SD acts as a critical role in many PMU-based applications and it is potentially subjected to malicious data spoofing attacks due to the lack of security mechanism in the widely adopted SD specifications. Considering the imperative need for defending against such spoofing attacks, this paper proposes a novel SD Source Authentication (SDSA) scheme by sufficiently exploiting multifractal coupling correlations of SD at multiple locations. Without the need for detailed knowledge of power networks (i.e., system topology and associated parameters) and costly upgrading the existing SD acquisition infrastructure (i.e., PMU hardware and SD transfer/storage device), the proposed method performs model-free and cost-effective SDSA in power systems from a new data-driven perspective of long-range coupling correlation discovery. Specifically, Multiscale Adaptive Coupling Correlation Detrended Analysis (MACCDA) is first developed to reveal the significant coupling multifractal characteristics of time series SD at multiple locations over a broad range of scales simultaneously from which the scale with the most significant multifractality is determined. Then the origin of multifractality and the contribution of SD at each individual location to the overall coupling correlation is quantified by shuffling and surrogating the original SD. Such contribution is further integrated with enhanced Weighted Multifractal Surface Interpolation (WMFSI) to generate synthetic high-resolution SD. Afterwards, distinctive time–frequency signatures are derived from the synthetic SD and they are used by computational intelligence algorithms for SDSA. Simulation results using the real-life SD of Victoria state demonstrate the reliability, efficiency and scalability of the proposed scheme in practical power grids. [ABSTRACT FROM AUTHOR]

Recently, there has been growing interest in the provision of market services from distributed energy resources (DERs). In pursuing this goal, demand response (DR) aggregators continue to face challenges in retaining privacy and comfort for end-users, mitigating scalability issues while controlling a large cohort of DERs and handling uncertainties which are inevitable in a practical setting. This paper presents an end-user privacy and comfort preserving, scalable, hierarchical control scheme for inverter-type air conditioners to provide real-time market services in the presence of uncertainties. Privacy and scalability are achieved thorough the adoption of the alternating direction method of multipliers (ADMM) framework which ensures minimal reliance on local information whilst ensuring desired reference tracking without compromising the end-user comfort. Benefiting from the proposed non-conservative robust MPC design, the local control is able to account for mismatches in outdoor temperature predictions. The overall scheme is validated using real data obtained from the Australian Energy Market operator. The results demonstrate that the proposed approach can achieve desired tracking of the reference signal while regulating indoor temperature within a narrow range (±1 °C) from the nominal set-point. Besides, the robustness to uncertainties is achieved without compromising computational performance and therefore the approach is scalable. • A hierarchical control scheme for inverter-type air conditioners to provide market services. • The uncertainty in outdoor temperature predictions is considered. • A combination of ADMM and robust MPC is employed. • The overall approach is scalable and preserves end-user data privacy. [ABSTRACT FROM AUTHOR]

Uncertainties at end-user and aggregator levels can be highly detrimental to the practical implementation of residential load control schemes for electricity market applications. Uncertainty factors such as end-user non-compliance, comfort violations and load set-point changes associated with the demand response aggregator are unavoidable in practice. This paper proposes a novel two-stage control algorithm for robust centralised management of aggregate residential loads which guarantee precise load set-point tracking in the presence of uncertainties occurring in real-time while ensuring that end-user thermal comfort is not compromised. The approach is underpinned by optimal selection of appliances based on an emulated supply curve followed by solving a one-step-ahead optimisation problem. Using air conditioners and water heaters as the controllable loads, the paper illustrates the effectiveness of the proposed approach in load management whilst mitigating the effects of unknown uncertainties. Further, the developed control scheme is compared with an existing industry approach. The results yield that the proposed control scheme is robust to uncertainties, preserves thermal comfort and is applicable for practical implementation under existing demand response standards. • A two-stage control scheme is proposed for robust management of residential loads. • The controller performance is studied under three different uncertainty scenarios. • The end-user thermal comfort is not compromised for the entire control period. • The proposed control scheme is consistent with existing demand response standards. [ABSTRACT FROM AUTHOR]

To effectively coordinate the distributed energy resources calls for reasonable energy management methods. Nowadays, there are a great number of studies about home energy management systems (HEMSs) and centralised control. However, the former has the problem of producing new peaks and valley when incentives are applied, and the latter only focuses on overall economic benefits and ignores individual preferences. Therefore, the authors take an emerging decentralised solution, i.e. peer‐to‐peer (P2P) energy sharing mechanism, into consideration and then propose an autonomous energy community model. In this P2P autonomous energy community, participants form an alliance and can trade energy with each other to maximisation individual benefit without a central controller. To allocate profit fairly among members, an energy contract based on Shapley values is proposed. Modelling of participants, implementation of energy contract and operation principle of community is presented in this study. Finally, case studies are conducted with the comparison of the model where households apply HEMS independently. The results show that the proposed model yields reduction in electricity cost and it is also friendly to the power grid with lower energy fluctuation compared with the counterpart. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wastewater significantly stimulated GHG productions in the mangrove and salt marsh sediments. • Salt marshes had much higher CO 2 and CH 4 emissions and lower N 2 O emissions than mangroves with wastewater input. • The saltmarsh sediments with wastewater input had less global warming potential than mangrove sediments. Wastewater discharge and salt marsh invasion are two main disturbances in global mangrove wetland ecosystems, but their combined effects on greenhouse gas (GHG) emissions remain unclear. Here, we performed a laboratory incubation experiment by adding wastewater (aquaculture and domestic wastewater) to mangrove and salt marsh sediments. Dissolved GHGs (CO 2 , CH 4 and N 2 O) and environmental parameters were measured over a time series of 50 days. The nitrification and denitrification rates and corresponding functional gene abundances (AOA, AOB, nirS , and narG) were also quantified. The results show that wastewater addition significantly increased GHG emissions and global warming potential (GWP) in wetland sediments (p < 0.05 for both). Compared with mangroves, salt marsh sediments produced more carbon GHGs (CO 2 and CH 4) but less N 2 O after wastewater input. These different stimulatory effects could be explained by the nitrogen and carbon substrate availability, organic matter quality, and functional gene abundances in sediments. Assessing GHG emissions as CO 2 equivalents, future scenarios of increasing salt marsh invasion with wastewater addition would increase the GWP caused by CO 2 and CH 4 , decrease blue carbon sequestration potential in wetlands, and decrease the GWP caused by N 2 O and total GWP, indicating a great impact on global climate change and important implications for managing coastal wetlands. [ABSTRACT FROM AUTHOR]

Extreme electricity prices occur with a higher frequency and a larger magnitude in recent years. Accurate forecasting of the occurrence of extreme prices is of great concern to market operators and participants. This paper aims to forecast the occurrence probability of day-ahead extremely low and high electricity prices and investigate the relative importance of different influencing variables. The data obtained from the Australian National Electricity Market (NEM) were employed, including historical prices (one day before and one week before), reserve capacity, load demand, variable renewable energy (VRE) proportion and interconnector flow. A Multivariate Logistic Regression (MLgR) model was proposed, which showed good forecasting capability in terms of model fitness and classification accuracy with different thresholds of extreme prices. In addition, the performance of the MLgR model was verified by comparing with two other models, i.e., Multi-Layer Perceptron (MLP) and Radical Basis Function (RBF) neural network. Relative importance analysis was performed to quantify of the contribution of the variables. The proposed method enriches the theories of electricity price forecast and advances the understanding of the dynamics of extreme prices. By applying the model in practice, it will contribute to promoting the management of operation and establishment of a robust energy market. • The occurrence of extremely low and high electricity prices was forecasted. • A multivariate logistic regression (MLgR) model was proposed to perform the forecast. • Model fitness and classification accuracy of the model were evaluated. • The accuracy of MLgR model was verified by comparing with two neural networks. • Relative importance of various variables on extreme prices was quantified. [ABSTRACT FROM AUTHOR]

[Display omitted] • Combination of microbiological, hydrological and biogeochemical approaches revealed how porewater exchange regulates nutrient cycling. • Mangrove had a net export of NH 4 -N but a net import of NO x -N and DIP. • Salt marsh had a net import of all forms of dissolved N and P. • High nitrogen loading from mangrove groundwater increased DIN:DIP ratio of surface water. • Mangrove-salt marsh ecotone was conductive to alleviate the N-associated eutrophication potential of coastal waters. Coastal wetlands regulate nutrient fluxes from the continents to the oceans. Salt marshes are rapidly encroaching into mudflat area in mangrove wetlands, shaping a mangrove-salt marsh ecotone, with unknown implications to coastal biogeochemical cycles. Here, we hypothesized that nitrogen and phosphorus cycling varied in mangrove and salt marsh, having significant implication on coastal waters. We investigated a tidal creek with a marked mangrove-salt marsh gradient in China using high-frequency time-series sampling of dissolved nutrients and observations of porewater exchange rate across the sediment–water interface over a spring-neap tidal cycle. The nitrogen transformation rates and microbiological activities were also investigated to explain the variability in nitrogen concentrations. The mangrove had net groundwater outflow rates of 3.6–4.3 mm d-1 while the salt marsh had net infiltration of surface water with rates of 0.5–2.9 mm d-1. Salt marsh had less capacity for ammonium (NH 4 -N) production (mineralization and dissimilatory nitrate reduction to ammonium DNRA) than mangrove. Denitrification dominated nitrogen removal reaching 97% and 83% in mangrove and salt marsh, respectively. Microbe distributions were consistent with nitrogen transformations with larger nirS and nrfA abundances for denitrification and DNRA in the mangrove than salt marsh. The mangrove had a net export of NH 4 -N but a net import of NO x -N (sum of nitrate and nitrite) and dissolved inorganic phosphorus (DIP) during the monitoring period. In contrast, the salt marsh had lower efflux of nutrient than influx leading to a net nutrient import during the monitoring period. Porewater released from the mangrove had a large DIN:DIP mole ratio (706 ± 236) due to high NH 4 -N concentrations, while NH 4 -N in the salt marsh were lower than in the mangrove. Overall, this study revealed that mangrove-salt marsh ecotone will push the native mangrove wetlands from being a source towards a sink of NH 4 -N to coastal waters by decreasing porewater exchange, modifying the nutrients stoichiometry, and ultimately alleviating the potential of N-associated eutrophication in nearby coastal waters. [ABSTRACT FROM AUTHOR]

• Feasibility of a voltage management approach in a distribution feeder is studied. • A double-auction based transactive control is designed for voltage management. • Closed form expression of market clearing var dispatch signal is derived. • Real-time demonstration of the proposed approach is provided for a use-case. • Simulation is performed in both software-in-loop and hardware-in-loop platforms. This article evaluates the feasibility of a double-auction-based Transactive Energy System (TES) for engaging the reactive power (VAR) capability of inverters in a utility-scale photovoltaic (PV) plant for voltage management in distribution feeders. In the proposed approach, a PV plant owner (seller) provides VAR supply curves in terms of price-quantity pairs considering the inverters' P-Q capability, efficiency, opportunity cost for real power curtailment, losses, etc. At the same time, the utility (buyer) proposes VAR demand curves in price-quantity pairs exhibiting the marginal price of VAR. Market clearing points are obtained from the intersection points of supply and demand curves which are then used to create VAR dispatch signals from the PV plant. To conduct a feasibility study of this approach, an Australian distribution network with a utility-scale PV plant (capacity 3.275 MW P) is modeled in RSCAD and simulated in real-time on MATLAB, RSCAD-RTDS co-simulation platform using real historical data. Considering a use case, namely, conservation voltage reduction (CVR), the operational feasibility along with cost-benefit analysis is demonstrated in software-in-the-loop (SIL) and hardware-in-the-loop (HIL) platform. Another use case, exploring the benefit from the tap-change reduction of step-voltage-regulator, is investigated. These two use cases yield net positive benefit when the partially loaded inverter is engaged to sink VAR without curtailing its real power. These studies explore further use cases, e.g., PV hosting capacity, network reconfiguration, etc., to be incorporated in TES for experiencing substantial economic benefits. [ABSTRACT FROM AUTHOR]