水面无人艇动力电力系统架构论证分析

水面无人艇是高度自主、高度智能化的无人化装备,动力电力系统是确保无人艇承担任务使命和正常运行的重要保障。论文分别以10吨级小型通用型无人艇、100吨级中型反潜型无人艇和500吨级大型攻击型无人艇为研究对象,对其动力电力系统的主要形式、系统组成及架构、设备配置以及关键战技指标等进行论证,为我国后续水面无人艇动力电力系统的发展提供参考。

基于Petri网和多种群遗传算法的海洋核动力平台电力系统网络重构

针对现有海洋核动力平台电力系统网络重构方法中功率流分析复杂,且重构模型求解算法难以稳定收敛到全局最优解的问题,提出一种基于Petri网和多种群遗传算法的核动力平台电力系统网络重构方法。综合故障后负荷恢复量、开关操作代价和发电机运行效率指标建立系统网络重构目标函数;基于Petri网对系统进行拓扑建模,将储能装置等效为负值"负荷",通过动态更新机制确定功率流分布;采用多种群遗传算法求解网络重构问题,获取满足系统约束的最佳开关状态组合方案。典型核动力平台电力系统算例表明,所提方法能有效防止算法局部收敛以及减少迭代次数,快速提供完备的系统重构方案。

民用核动力船舶电力系统方案研究

本文以民用核动力船舶的发展方向为立足点,充分考虑民用核动力船舶的安全性、可靠性、冗余性、经济性设计需求,给出了不同用途下的民用核动力船舶电力系统解决方案。此外,针对自航类核动力船舶所有交流电源失效的可能性和救援的时差性,提供了一种增加附加直流电源来保证安全性的解决方案。

Research on electromagnetic relay's dynamic characteristics disturbed by uniform static magnetic field

Electromagnetic relay is a widely used apparatus which usually works in a magnetic disturbance environment. To evaluate its electromagnetic compatibility (EMC) in a static magnetic field, dynamic characteristics of a clapper relay in a uniform static magnetic field situation based on the finite element method (FEM) is studied. Influences of the magnetic field on dynamic parameters (delay time, pick-up time, end pressure, and final velocity) as well as a situation in which the relay cannot function normally are analyzed. Simulation reveals that the external magnetic field which weakens the relay’s air-gap field has a greater influence on the relay’s dynamic parameters than the one strengthening the field. The validity of the simulation is verified by measured results of coil current and armature displacement.

Dynamic Modeling of Tubular SOFC for Marine Power System

Solid oxide fuel cell (SOFC) has been identified as an effective and clean alternative choice for marine power system.This paper emphasizes on the dynamic modeling of SOFC power system and its performance based upon marine operating circumstance.A SOFC power system model has been provided considering thermodynamic and electrochemical reaction mechanism.Subcomponents of lithium ion battery, power conditioning unit, stack structure and controller are integrated in the model.The dynamic response of the system is identified according to the inertia of its subcomponent and controller.Validation of the whole system simulation at steady state and transit period are presented, concerning the effects of thermo inertia, control strategy and seagoing environment.The simulation results show reasonable accuracy compare with lab test.The models can be used to predict performance of a SOFC power system and identify the system response when part of the component parameter is adjusted.

A novel dynamic equivalence method for grid-connected wind farm

Dynamic equivalence of the wind farm is a fundamental problem in the simulation of a power system connected with wind farms because it is unpractical to model every generator in a wind farm in detail. In this paper, an Equivalence Method based on the Output Characteristics (EMOC) is proposed, with which the wind farm composed of Squirrel-Cage Induction Generators (SCIGs) can be equivalent to one generator. By considering the diversity of wind generators and special operating characteristics of a wind farm, the equivalent generator based on EMOC responds accurately in various faults. No matter whether the wind farm is integrated in grid or just programmed, EMOC can be used to acquire an accurate equivalent generator. Simulation of the dynamic equivalence of an SCIG wind farm validated the method.

Intelligent power factor compensation equipment of three phase low voltage loads

An intelligent power factor correction scheme is presented for three phase low power factor loads. This new scheme is able to perform individual phase sensing of parameters by monitoring at all times to sense a change in system parameters and affects individual phase correction by applying the exact amount of reactive components needed for each phase, and can also reduce negative sequence current caused by the load to improve system balance. An optimization criterion is used for the proper calculation of reactive power steps in a power compensation installation of capacitor banks. The criterion is enabled by sampling measurements performed on the electrical plant examined within specific interval of time.

Research and practice of designing hydro/ photovoltaic hybrid power system in microgrid

Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.

WAMS-based monitoring and control of Hopf bifurcations in multi-machine power systems

A method is proposed to monitor and control Hopf bifurcations in multi-machine power systems using the information from wide area measurement systems (WAMSs). The power method (PM) is adopted to compute the pair of conjugate eigenvalues with the algebraically largest real part and the corresponding eigenvectors of the Jacobian matrix of a power system. The distance between the current equilibrium point and the Hopf bifurcation set can be monitored dynamically by computing the pair of con- jugate eigenvalues. When the current equilibrium point is close to the Hopf bifurcation set, the approximate normal vector to the Hopf bifurcation set is computed and used as a direction to regulate control parameters to avoid a Hopf bifurcation in the power system described by differential algebraic equations (DAEs). The validity of the proposed method is demonstrated by regulating the reactive power loads in a 14-bus power system.

Design of Hybrid Compensators for Power Quality Improvement of Oilfield Drilling Electrical System

With large-scale use of kinds of motors, oilfield drilling electrical system always accompanied by serious power quality problem, including reactive current, harmonics current and grid voltage distortion, which would greatly threaten the safety and proper working of the whole system. This paper focuses on a power quality improvement project to solve these problems. A hybrid compensating scheme, including an active compensator and a passive compensator, is carried out. Because of the specificity of oilfield drilling electrical system, compensators are redesigned against features of this application background. And then the current detection point arrangement of this hybrid system is also taken into consideration to build the whole system much more effective and reliable. Now the improvement project is already implemented in application field, and the power quality of the system is greatly improved.

Smart Meters and Under-Frequency Load Shedding

In some countries, there exists a risk of power deficit in the EPS （electrical power system）. This is a very serious problem and there are various solutions to deal with it. A power deficit in the EPS leads to frequency decrease in the power system. A dedicated automation to load shedding is used to maintain proper EPS operation. For some time, it has applied a mechanism called demand-side response, which in case of an emergency situation allows for a ＂more civilized＂ rationing of electricity to customers, with their consent. Such programs require that the utilities pay the customers for their agreement. The author proposes a new solution, intermediate between strict ALS （acting relieving automation） and demand-side response programs, where the companies have to send information about the price of energy or control signals to households.

Pure Jatropha Oil for Power Generation on Floreana IslandlGalapagos： Four Years Experience on Engine Operation and Fuel Quality

In the small country of Ecuador, all environmental risks of the production and consumption of fossil fuels can be observed by damages through oil exploration in the amazonite rainforest and two tank ship accidents close by Galapagos Islands causing death of 10,000 marine iguanas and other species. Now Ecuador plans to replace all environmentally dangerous diesel generators from all four inhabited Galapagos Islands by a hybrid system using 100% renewable energy for electricity production. Since 2010 a hybrid system of two Jatropha oil generators with an electrical power of 69 kW （kWel） and a photovoltaic plant with an electrical peak power of 21 kW （kWpeak） is successfully providing electricity from renewable energy for inhabitants and tourists of Floreana Island. After more than 15.000 engine operation hours of each engine there is no engine defect. For fuel supply, the so-called ＂Living Fence＂ concept collecting Jatropha seeds by farmers and families from already existing 6,000 km hedges on Ecuadorian mainland was chosen to comply with highest biofuel sustainability standards. The Jatropha oil is produced in a decentralized so-called CompacTropha oil mill container following the ambitious German fuel quality standard DIN51605. Since 2010 Floreana project successfully demonstrates that it is possible to replace diesel gen sets by generators fueled with pure Jatropha oil from decentralized sustainable production.

Aerodynamic Effects on TLP Type Wind Turbines and Predictions of the Electricity They Generate

This research proposes a new offshore wind energy generation system that uses a tension leg platform (TLP) and describes experiments performed on a TLP type wind turbine in both waves and wind. The following conclusions can be made from the results of this research. 1) In the case of coexisting wave-wind fields, the wind effect stabilizes the pitch motion. 2) The wind effect decreases vibration of the mooring lines when waves and wind coexist. In particular, the springing (2nd or 3rd order force) also decreases in this field. 3) It can be estimated that the reduction in the rate of generation of electrical power can be up to about 6% as a result of the heel angle. In addition, the annual amount of electricity generated was estimated along with the utilization factor based on the experimental results.

Power System Dynamical Simulation Application for Out-of-Step Relay Testing

OOS （out-of-step） condition prevention becomes an imperative task to avoid possible power system blackout and collapses. To be confident in correct OOS relaying, the OOS protection device behavior under the vast majority of power system abnormal regimes should be tested. Comprehensive testing procedure becomes especially important for complex power systems when power system parameters and consequently device settings are not clearly defined or may vary in time. For such complex systems the real OOS protection device testing may become a problem because of specific waveforms of signals persisting during OOS condition. The goal of the methodology, presented in the paper, is to achieve the possibility of out-of-step protection device testing under close-to-real power system operation conditions. The power system stability modelling software is used as a source of test signals. The accurate model of power system in conjunction with dynamical modelling features allows to verify the reliability of OOS protection scheme under consideration as also allows the device settings correction, if necessary. The methodology allows to test the real device with signals waveforms which are hardly obtainable using traditional testing technique.

Research on Wind Farm Participation in Power Grid AGC Control

Since wind power has the features of being intermittent and unpredictable, and usually needs transmission over long distances, grid integration of large-scale wind power will exert signif icant influence on power grid planning and construction, and will make a heavy impact on the safe and reliable operation of power systems. To deal with the diff iculties of large scale wind power dispatch, this paper presents a new automatic generation control (AGC) scheme that involves the participation of wind farms. The scheme is based on ultra-short-term wind power forecast. The author establishes a generation output distribution optimization mode for the power system with wind farms and verif ies the feasibility of the scheme by an example.

Performance analysis for power generating system by using matrix method

We verified that the matrix method, a process analysis method used mainly for life cycle inventory analysis, has several advantages in the analysis of power systems, which have recently become more complex to enhance efficiency and to reduce C02 emissions. While designing a conceptual thermodynamic model of a complex power system, the matrix method provides a definite procedure and facilitates calculations, even if there is a recttrsive loop between the upstream and downstream processes. Similarly, in the case of partial modification to the constructed model, the matrix method can potentially reduce the time and effort required to calculate the thermodynamic balances, even if the constructed model is designed by others. In this study, we obtained mass flow and energy balances of example model power systems by the matrix method from the common thermodynamic conditions including temperatures and pressures which are set on the basis of an existing industrial steam power system. While analyzing the environmental impact of complex multiproduct power systems, such as carbon emissions, the matrix method can be used to easily derive the environmental impact of each final product. We could verify the efficacy of the matrix method in accurately deriving that of an example model power system.