In this paper, the authors will introduce a two-level voltage stability evaluation method consists of control center level and substation level. At control center level, some certain sensitivities related with operation state of overall system are calculated and these variables are sent to several substations. At substation level, the proposed method adopts a different system model rather than Thevenin Equivalent Circuit, such that the results of local voltage stability assessment are more accurate than traditional distributed methods. The performance of the proposed method is tested on IEEE 39-bus system.

This paper presents an optimal power flow (OPF) model for AC/DC meshed networks with Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) system. The OPF problem is formulated to minimize the total network loss of the whole AC/DC grids by adjusting generators and modular multilevel converters considering N-1 constraints and post-contingency corrective control. A practical method is proposed to handle N-1 static security constraints and corrective control with OPF more effectively. Simulations are conducted on IEEE 39-bus testing system and a practical power grid. The results demonstrate the effectiveness of the approach.

1ABSTRACT: This paper presents an optimal power flow (OPF) model for meshed AC/DC networks based on modular multi-level converter. OPF problem is formulated to minimize total network loss of whole AC/DC grids by adjusting generators and modular multi-level converters withN?1 constraints involved. A practical method is proposed to deal withN?1 static security-constraints with OPF. Case studies of IEEE testing cases and a practical network are carried out with results demonstrating effectiveness of the approach.

Heat-shock protein 90 (Hsp90) is highly expressed in many tumor cells and is associated with the maintenance of malignant phenotypes. Targeting Hsp90 has had therapeutic success in both solid and hematological malignancies, which has inspired more studies to identify new Hsp90 inhibitors with improved clinical efficacy. Using a fragment-based approach and subsequent structural optimization guided by medicinal chemistry principles, we identified the novel compound CPUY201112 as a potent Hsp90 inhibitor. It binds to the ATP-binding pocket of Hsp90 with a kinetic dissociation (Kd) constant of 27 ± 2.3 nM. It also exhibits potent in vitro antiproliferative effects in a range of solid tumor cells. In MCF-7 cells with high Hsp90 expression, CPUY201112 induces the degradation of Hsp90 client proteins including HER-2, Akt, and c-RAF. We prove that treating MCF-7 cells with CPUY201112 results in cell cycle arrest and apoptosis through the wild-type (wt) p53 pathway. CPUY201112 also synergizes with Nutlin-3a to induce cancer cell apoptosis. CPUY201112 significantly inhibited the growth of MCF-7 xenografts in nude mice without apparent body weight loss. These results demonstrate that CPUY201112 is a novel Hsp90 inhibitor with potential use in treating wild-type p53 related cancers.

In recent years, because of the interconnection of large grids and the accession of HVDC, real-time analysis approach is needed for transient voltage security (TVS) analysis. Traditional simulation analysis is time-consuming and the transient energy function approach is difficult to analyze large scale power systems. In this paper, an approach for real-time TVS analysis is proposed based on off-line database. A new transient voltage security index (TVSI) is defined in this paper. Firstly, a lot of operation modes that meet the constraints of steady state operation are generated. Then the TVSIs under these operation modes are computed to form an off-line database. Next, the TVS analysis of current operation mode can be carried out based on data fitting of current operation mode using the off-line database. At last, two case studies based on the New England 39 bus test system are presented to verify the effectiveness of the approach.

With the large-scale development of electric vehicles, the ratio of the peak electric vehicle charging load to the total network load is rising day by day, which would have a negative impact on the static voltage stability of the power gird. This paper attempts to incorporate electric vehicle charging equipment into power system control, thereby reducing this negative impact. Firstly, three kinds of EV charging control method are proposed and their control effects are compared. The simulation and comparison show that all the three kinds of control methods could increase the load margin of the power grid, but the droop control method is more suitable for practical use. Then the droop control method is applied to New England 39-bus system to analyze its effect on load margin under different permeability and charging rate. The results show that the droop control method could increase the load margin obviously, it is an effective method for electric vehicle charging equipment local control.

The voltage and reactive power (VAR) management in the power system operation has becoming more challenging than ever. This is mainly due to long distance of power generations to the load centers and mesh interconnection of power grids. Coordinated Voltage Control (CVC) is found to be the most effective solutions for voltage and VAR control. This can be achieved by coordinating reactive power resources at transmission system to achieve a better voltage profiles and to minimize active power losses. This paper presents a systematic study of a hierarchical structure of system-wide automatic Coordinated Voltage Control for TNB system. Through a collaboration between TNB Research and Tsinghua University, a comprehensive simulation study of CVC system based on the approach developed by Tsinghua University has been carried out. The simulations are based on the recursive power flow solutions of the real-time snapshots which are obtained from TNB Energy Management System (EMS). The simulation results on Adaptive Zone Division (AZD), Tertiary Voltage Control (TVC) and Secondary Voltage Control (SVC) are presented in this paper. Furthermore, voltage profiles, system losses and VAR reserves before and after CVC are being analyzed. The results are encouraging. Therefore, the implementation of an automatic CVC system in TNB power grid is being realized.

Herein we first reported hierarchical structure-based virtual screening utilizing the receptor–ligand binding model of Nrf2–Keap1. The most promising compound, 15, which is one of the most potent direct PPI inhibitors of Nrf2–Keap1 reported so far, can effectively disrupt the Nrf2–Keap1 interaction with the in vitro EC50 of 9.80 μM in the fluorescence polarization (FP) assay. 15 can also activate the Nrf2 transcription activity in the cell-based ARE–luciferase reporter assays in a dose-dependent manner. The compound can serve as a promising starting point for the discovery of potent inhibitors of Nrf2–Keap1 interaction.

With the raising of requirement of power grid operation to voltage control and reactive power management level,automatic voltage control(AVC) becomes a hot spot in the research.Due to the constraints in the management mode,the applied research of AVC is hitherto a blank in North America power grids.An AVC system,which is suitable to special management modes of a certain interconnected power grid in Northeast U.S.and can meet the demand of on-line operation,is designed and implemented.In the designed system,phase shifter models are added into power flow modules and during the computation of control strategy by optimal power flow(OPF) the static security constraints after the assumed faults are considered.Both the data and assessment results of long-term on-line trail-operation show that the reactive power and voltage level of the interconnected power grid can be improved by applying the designed AVC system,and both security and economy of the interconnected power grid can be enhanced.

Heat shock protein 90 (Hsp90), whose inhibitors have shown promising activity in clinical trials, is an attractive anticancer target. In this work, we first explored the significant pharmacophore features needed for Hsp90 inhibitors by generating a 3D-QSAR pharmacophore model. It was then used to virtually screen the SPECS databases, identifying 17 hits. Compound S1 and S13 exhibited the most potent inhibitory activity against Hsp90, with IC50 value 1.61±0.28 μM and 2.83±0.67 μM, respectively. Binding patterns analysis of the two compounds with Hsp90 revealed reasonable interaction modes. Further evaluation showed that the compounds exhibited good anti-proliferative effects against a series of cancer cell lines with high expression level of Hsp90. Meanwhile, S13 induced cell apoptosis in a dose-dependent manner in different cell lines. Based on the consideration of binding affinities, physicochemical properties and toxicities, 24 derivatives of S13 were designed, leading to the more promising compound S40, which deserves further optimization.

Protein-protein interactions (PPIs) play a crucial role in cellular function and form the backbone of almost all biochemical processes. In recent years, protein-protein interaction inhibitors (PPIIs) have represented a treasure trove of potential new drug targets. Unfortunately, there are few successful drugs of PPIIs on the market. Structure-based pharmacophore (SBP) combined with docking has been demonstrated as a useful Virtual Screening (VS) strategy in drug development projects. However, the combination of target complexity and poor binding affinity prediction has thwarted the application of this strategy in the discovery of PPIIs. Here we report an effective VS strategy on p53-MDM2 PPI. First, we built a SBP model based on p53-MDM2 complex cocrystal structures. The model was then simplified by using a Receptor-Ligand complex-based pharmacophore model considering the critical binding features between MDM2 and its small molecular inhibitors. Cascade docking was subsequently applied to improve the hit rate. Based on this strategy, we performed VS on NCI and SPECS databases and successfully discovered 6 novel compounds from 15 hits with the best, compound 1 (NSC 5359), K(i) = 180 ± 50 nM. These compounds can serve as lead compounds for further optimization.

By substituting the slow dynamic var compensator (such as synchronous generator) for rapid dynamic var compensator (such as SVC/SVG) in the static conditions, the rapid dynamic reactive power reservation can be significantly boosted. Therefore, the reactive power reservation can respond to the dynamic network disturbance more effectively. This paper proposes a quadratic programming based optimization model to implement the idea of substituting the slow dynamic reactive power for the rapid dynamic reactive power on the premise of ensuring the system security and keeping an approximate constant voltage of pilot buses. It can keep SVC/SVG a large upward and downward reactive power reservation and ensure the regional balanced reactive power of generators. Simulation results on the New England 39-bus system show that regional rapid dynamic reactive reservation is enhanced and the dynamic voltage stability is improved after the substitution.

PJM Interconnection operates the largest synchronized transmission system in North America, where one of the great challenges is being able to meet the system-wide voltage control performance requirements both pre- and post-contingency. Based on a characteristic analysis of the contingencies distribution, a practical method using an iteration scheme between the optimal power flow (OPF) and a contingency assessment (CA) is proposed to develop a control strategy, so that the calculated optimal voltage schedule solutions are better not only for pre-contingency system conditions, also for the post-contingency (N-1) system conditions. At step T, a CA considering all contingencies is carried out and those that may lead to the maximized voltage violations are saved as active contingencies for step T+1. At the same time, another CA, considering only the current active contingencies, is computed in parallel using a trial OPF result as input. According to the post-contingency indices, the new voltage constraints will be compressed and the final OPF is called again to calculate the optimal strategies. The detailed architecture of the PJM optimal voltage control (OVC) system is presented in this paper. The system has completed four-months of online operation, and the results have been evaluated using third-party software. It has been proven that the OVC system presented here will greatly improve both the pre- and post-contingency performance. The PJM OVC is a typical application of a smart transmission grid. Phase III of this study is currently under way.

To coordinately consider the economy and security of the system during reactive voltage control,a multi-objective reactive power optimization model is proposed.Apart from the conventional economic objective,the new model has the system static security added to the multi-objective to seek their optimization simultaneously.And the solution for the model is proposed based on the cooperative game theory.As two players of the game,the economy side and the security side decide on their game strategies alternately until equilibrium is attained.Tests on a 2-bus system and IEEE 9-bus system demonstrate the feasibility and advantages of the model along with the proposed method.