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Abstract The interconnection of remote large power systems, and the connection of large non-synchronous renewable power sources to AC power systems have found solutions by means of transmission in high voltage direct current (HVDC) using technology based on voltage source converters (VSC). This technology has the advantage of fast response the possibility of providing reactive power to AC systems, and the use of supplementary control signals to their automatic voltage regulators to improve stability AC systems. This paper proposes the computation of robust supplementary controller type H ∞ based on low-order models of the power system, obtained by application of N4Sid identification technique, to be installed at the VSC converter stations of a HVDC link to dampen electromechanical weak modes. The proposed model shows that using simulated input/output data by means of typical software available at utilities is possible and useful. The methodology includes the modeling of uncertainties due to the different operational points where the power system can be placed by load variations and generation dispatch. This paper also presents a methodology for the computation of robust supplementary control at VSC-HVDC stations that guarantee robustness in a wide range of operating conditions and even better to improve the damping of electromechanical oscillations. It is also proposed a methodology for defining the weighted functions based on the uncertainties theory. Likewise, it is validated with the simulation of a critical contingency in a weakly damped system obtaining an improvement in damping of electromechanical oscillations. The robust supplementary control is compared to the performance of the classical POD. Highlights • Low-order dynamic model of power systems by means of N4Sid using simulated I/O data. • An uncertainties’ estimation of the dynamic model of the power system. • Definition of weighting matrices for computing H ∞ controllers in power systems. • Application for damping weak electromechanical modes by means of VSC-HVDC converters. [ABSTRACT FROM AUTHOR]

Automatic voltage regulators and power system stabilizers have been employed successfully to deal with fast dynamics associated to local oscillations phenomena. Whereas, inter-area oscillations damping in large power systems requires remote feedback controllers fed by Wide Area Monitoring Systems (WAMS). Although these improvements in the inter-area oscillations behavior have been effective, a new challenge emerges: reaching stability with a closed loop control despite latencies due to measurements taken far away from the control centre. The research was motivated by the need for modernization of power systems capable of dealing with control difficulties in centralised WAMS for damping inter-area oscillations in power systems caused by delays in the communication system. Herein, time delay and control problems are addressed separately. The time delay problem is solved by a database based time compensation solution relying on the most updated available state of the system. The control problem is solved by a Model Predictive Control (MPC) with terminal cost and constraint set to handle complexities due to nonlinearities of the power system, the large scale of the problem and the parametric variations. Both solutions work in a coordinated way with local controllers to implement a decentralised coordinated strategy that manages slow global dynamics and fast local dynamics as well. The integrated proposed approach is called Time-Delay-Tolerant Model Predictive Control (TDT-MPC). Coordinated and coherent performance of the two TDT-MPC components (Kalman compensator and MPC) is achieved thanks to unifying power system reference models for both strategies. The approach has been tested on the IEEE 39 system and validated with time domain nonlinear simulations, obtaining post-fault damped oscillations and a good tracking of new power references when tripping tie lines. [ABSTRACT FROM AUTHOR]

Highlights: [•] A multistage planning of PMUs placement for power systems is proposed. [•] The methodology takes into account network expansion plans. [•] System observability is maximized over time. [•] The methodology identifies nodes to locate PMUs based on security criteria. [•] The stepwise approach allows the utilities to develop a path for PMU placement. [ABSTRACT FROM AUTHOR]

Situational awareness has become an important subject for the operation of power systems because it will give information of the state of functioning of the system and important data for taking control actions in the power systems. Among the different aspects to be included in the situational awareness to be monitored in a wide-area monitoring system, the supervision of the behavior of damping of electromechanical modes has an important role. It is well known that this supervision corresponds to an estimation process of dynamic characteristics in a non-linear system. However, an important balance between the requirements of quantity of data and time for estimation must be achieved for this important task. So, this article proposes the utilization of both fixed sliding-window and size-controlled window analysis to be used in on-line wide-area monitoring system based identification of electromechanical modes using a multi-Prony estimation. The proposed methods are simulated for the reduced-order equivalent of the interconnected New England Test System and New York Power System. [ABSTRACT FROM AUTHOR]

Discusses the identification of regions of the tomato gamma-glutamyl kinase that are involved in allosteric regulation by proline. Significance of osmoregulation to agriculture; Post-transcriptional control mechanism; Structure of a proline binding site.

Biotechnological drugs (BTDs) are complex molecules whose manufacturing process precludes the ability to identically reproduce the structure of the original product, and therefore there cannot be an absolute equivalence between the original (innovative) medication and its biosimilar counterpart. BTDs have been proven useful in the treatment of several rheumatic diseases; however, their high cost has prevented their use in many patients. Several BTD patents have expired or are close to expire, triggering the development of structurally similar drugs with efficacy and safety profiles comparable to the innovative compound; however, these must be evaluated through evidence-based medicine. The Mexican General Health Law contemplates the registration of these biosimilar drugs for their use in our country. This document is a forethought from members of the Mexican College of Rheumatology, pharmacologists, and epidemiologists, in accordance with Mexican health authorities regarding the necessary scientific evidence required to evaluate the efficacy and safety of biosimilar drugs before and after their arrival to the Mexican market. [ABSTRACT FROM AUTHOR]

Background: We undertook this study to describe prescription practices and the degree of disease control in a large sample of patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS) treated by rheumatologists in Mexico. Methods: Board-certified Mexican rheumatologists across the country were asked to assess consecutive RA and AS patients; 1208 patients completed a self-administered questionnaire with information on demographics, disease duration, co-morbidity, treatment, pain, disability and a validated Spanish version of instruments to measure physical function and quality of life. Results: Of the 1096 RA patients, 88.1% were treated with nonsteroidal anti-inflammatory drugs (NSAIDs), 1020 (93.3%) with disease-modifying anti-rheumatic drugs (DMARDs), 365 (33.4%) with steroids, and 70 (6.4%) with biological agents. Their mean Health Assessment Questionnaire Disability Index (HAQ-Di) score was 1.21 ± 0.80, Disease Activity Index, 28 joint count (DAS 28) 3.9 ± 1.29, and Rheumatoid Arthritis Disease Activity Index (RADAI), 3.94 ± 2.01. Regarding the 112 AS patients, 110 (98.2%) received NSAIDs, 90 (80.4%) were on DMARDs, 11 (9.8%) took steroids, and 11 (9.8%) received biological agents, their functional status shown as Bath Ankylosing Spondylitis Functional Index (BASFI) score of 4.4 ± 2.5. Among the 1110 DMARD users, only 64 received one drug, and a great proportion used two or more DMARDs; 81 subjects (16.2%) were on biological agents, in any combination. RA patients more commonly used methotrexate, 791 (72%) cases, and hydroxychloroquine. Taking into account their diagnosis, the combination most prescribed was NSAIDs plus DMARDs in 660 subjects (54.7%). Conclusions: DMARDs in combination with other drug are the most frequently prescribed therapeutic scheme for RA and AS patients. These schemes used for both conditions by Mexican rheumatologists are in line with current international recommendations. [Copyright &y& Elsevier]