Electrochemical power sources:key agents for energy sustainability(Ⅱ)

3 Hydrogen distribution and storage3·1 Gaseous and liquid hydrogenIn the gaseous state,the most obvious method for distributinghydrogen would appear to be via pipeline·This has long been thepractice in Germany to supply hydrogen for chemical processes·…     

The 12th Five-Year: Speed Up Structural Adjustment of Power Sources

To the year 2020, China will realize the target of increasing non-fossil generation to 15% of the total energy consumption. Speeding up power sources restructuring comes up as an arduous task during the 12^th Five-Year Plan period. In this article, the author outlines the principles of structure adjustment for various kinds of power sources, and points out the issues needing attention during the restructuring.     

Issues and Solutions for China’s Photovoltaic Power Industry

Solar energy is an important renewable energy.Developing photovoltaic power will not ordy relieve the energy supply-demand contradiction and optimize the energy structure,but also help to restructure t...     

Swiss pumped hydro storage potential for Germany’s electricity system under high penetration of intermittent renewable energy

In order to cut greenhouse-gas emissions and increase energy security,the European Commission stimulates the deployment of intermittent renewable energy sources（IRES） towards 2050.In an electricity system with high shares of IRES implemented in the network,energy balancing like storage is needed to secure grid stability and smooth demand satisfaction.Pumped hydro storage（PHS） is at this moment the best option for large scale storage.Switzerland has strong ambitions to further develop their PHS sector and become the battery of Europe.In this research,the potential of the Swiss PSH plants is explored,whilst taking inflow into the upper reservoirs of the PHS plants into consideration.To simulate electricity imbalance,Germany is used as a case study.Germany already has a high penetration of IRES and has plans to increase installed IRES capacity.By using an energy planning model（Power Plan）,three future scenarios of the German electricity system were designed,each with a different set of IRES installed（solar,mixed and wind）.Results show that the Swiss battery ambition offers most benefits to a wind-oriented scenario,reducing both shortages as well as surpluses.Water inflow in Swiss PHS-reservoirs is of minor importance when looking at security of supply,although it was shown that the solarscenario profits more from inflow in terms of system stability.However,a potential conflict was observed in the solar-scenario between the need for electricity storage and the storage of natural inflow,resulting in more surpluses in the system when inflow was taken into account.     

Strategies for improving resilience of regional integrated energy systems in the prevention–resistance phase of integration

he construction of integrated energy systems can help improve energy efciency and promote global energy transition. However, in recent years, the occurrence of extreme natural disasters has brought certain threats to the safe and stable operation of the integrated energy system. Thus, it is necessary to improve the ability of the integrated energy system to resist disasters, reduce disaster losses, and restore energy supply as soon as possible, i.e., improve its resilience. Considering the infuence of pre-disaster prevention measures and disaster-time operational measures on system disaster resilience and the correlation between the two, this paper proposes a system hardening strategy based on three-layer robust optimization. The upper layer formulates the optimal hardening strategy of the system before the disaster event occurs, the middle layer identifes the failed elements in the worst disaster situation, while the lower layer realizes the system operational optimization by coordinating the energy storage charging and discharging plan of each subsystem. The strategy can reduce the total supply shortage of the integrated energy system and improve the fexibility of the system in the pre-disaster prevention and disaster resistance integration stages.     

Strategy of constructing virtual peaking unit by public buildings’ central air conditioning loads for day-ahead power dispatching

With the gradually widely usage of the air conditioning（AC） loads in developing countries, the urban power grid load has swiftly increased over the past decade.Especially in China, the AC load has accounted for over30% of the maximum load in many cities during summer.This paper proposes a scheme of constructing a virtual peaking unit（VPU） by public buildings’ cool storage central AC（CSCAC） systems and non-CSCAC（NCSCAC）systems for the day-ahead power network dispatching（DAPND）. Considering the accumulation effect of different meteorological parameters, a short term load forecasting method of public building’s central AC（CAC） baseline load is firstly discussed. Then, a second-order equivalent thermal parameters model is established for the public building’s CAC load. Moreover, the novel load reduction control strategies for the public building’s CSCAC system and the public building’s NCSCAC system are respectively presented. Furthermore, based on the multiple-rank control strategy, the model of the DAPND with the participation of a VPU is set up. The VPU is composed of large-scale regulated public building’s CAC loads. To demonstrate the effectiveness of the proposed strategy, results of a sample study on a region in Nanjing which involves 22 public buildings’ CAC loads are described in this paper. Simulated results show that, by adopting the proposed DAPND scheme, the power network peak load in the region obviously decreases with a small enough deviation between the regulated load value and the dispatching instruction of the VPU. The total electricity-saving amount accounts for7.78% of total electricity consumption of the VPU before regulation.     

Strategy of constructing virtual peaking unit by public buildings’ central air conditioning loads for day-ahead power dispatching

With the gradually widely usage of the air conditioning（AC） loads in developing countries, the urban power grid load has swiftly increased over the past decade.Especially in China, the AC load has accounted for over30% of the maximum load in many cities during summer.This paper proposes a scheme of constructing a virtual peaking unit（VPU） by public buildings’ cool storage central AC（CSCAC） systems and non-CSCAC（NCSCAC）systems for the day-ahead power network dispatching（DAPND）. Considering the accumulation effect of different meteorological parameters, a short term load forecasting method of public building’s central AC（CAC） baseline load is firstly discussed. Then, a second-order equivalent thermal parameters model is established for the public building’s CAC load. Moreover, the novel load reduction control strategies for the public building’s CSCAC system and the public building’s NCSCAC system are respectively presented. Furthermore, based on the multiple-rank control strategy, the model of the DAPND with the participation of a VPU is set up. The VPU is composed of large-scale regulated public building’s CAC loads. To demonstrate the effectiveness of the proposed strategy, results of a sample study on a region in Nanjing which involves 22 public buildings’ CAC loads are described in this paper. Simulated results show that, by adopting the proposed DAPND scheme, the power network peak load in the region obviously decreases with a small enough deviation between the regulated load value and the dispatching instruction of the VPU. The total electricity-saving amount accounts for7.78% of total electricity consumption of the VPU before regulation.     

Strategy of constructing virtual peaking unit by public buildings’ central air conditioning loads for day-ahead power dispatching

With the gradually widely usage of the air conditioning（AC） loads in developing countries, the urban power grid load has swiftly increased over the past decade.Especially in China, the AC load has accounted for over30% of the maximum load in many cities during summer.This paper proposes a scheme of constructing a virtual peaking unit（VPU） by public buildings’ cool storage central AC（CSCAC） systems and non-CSCAC（NCSCAC）systems for the day-ahead power network dispatching（DAPND）. Considering the accumulation effect of different meteorological parameters, a short term load forecasting method of public building’s central AC（CAC） baseline load is firstly discussed. Then, a second-order equivalent thermal parameters model is established for the public building’s CAC load. Moreover, the novel load reduction control strategies for the public building’s CSCAC system and the public building’s NCSCAC system are respectively presented. Furthermore, based on the multiple-rank control strategy, the model of the DAPND with the participation of a VPU is set up. The VPU is composed of large-scale regulated public building’s CAC loads. To demonstrate the effectiveness of the proposed strategy, results of a sample study on a region in Nanjing which involves 22 public buildings’ CAC loads are described in this paper. Simulated results show that, by adopting the proposed DAPND scheme, the power network peak load in the region obviously decreases with a small enough deviation between the regulated load value and the dispatching instruction of the VPU. The total electricity-saving amount accounts for7.78% of total electricity consumption of the VPU before regulation.     

Enhanced leader PSO (ELPSO): A new algorithm for allocating distributed TCSC’s in power systems

Allocation of flexible AC transmission systems (FACTS) devices is a challenging power system problem. This paper proposes a new particle swarm optimisation (PSO) variant, called enhanced leader PSO (ELPSO), for solving this problem. This algorithm is capable of solving FACTS allocation problem in a way leading to lower amounts of power flow violations, voltage deviations and power losses with respect to other optimisation algorithms. Distributed thyristor controlled series compensators (D-TCSC’s) are used. D-TCSC’s are installed at all branches except those with regulating transformers. The reactances of D-TCSC’s are found in optimisation process. ELPSO features a five-staged successive mutation strategy which mitigates premature convergence problem of conventional PSO. ELPSO and other optimisation algorithms are applied to IEEE 14 bus and 118 bus power systems for N-1 contingencies and also for simultaneous outage of four branches. The results show that it leads to lower amounts of power flow violations, voltage deviations and power losses with respect to conventional PSO (CPSO) and eight other optimisation algorithms including genetic algorithm (GA), gravitational search algorithm (GSA), galaxy based search algorithm (GBSA), invasive weed optimisation (IWO), asexual reproduction optimisation (ARO), threshold acceptance (TA), pattern search and nonlinear programming (NLP).     

Distributed multi-step Q(λ) learning for Optimal Power Flow of large-scale power grids

This paper presents a novel distributed multi-step Q(λ) learning algorithm (DQ(λ)L) based on multi-agent system for solving large-scale multi-objective OPF problem. It does not require any manipulation to the conventional mathematical Optimal Power Flow (OPF) model. Large-scale power system is first partitioned to subsystems and each subsystem is managed by an agent. Each agent adopts the standard multi-step Q(λ) learning algorithm to pursue its own objectives independently and approaches to the global optimal through cooperation and coordination among agents. The proposed DQ(λ)L has been thoroughly studied and tested on the IEEE 9-bus and 118-bus systems. Case studies demonstrated that DQ(λ)L is a feasible and effective for solving multi-objective OPF problem in large-scale complex power grid.     

Novel chaos game optimization tuned-fractional-order PID fractional-order PI controller for load–frequency control of interconnected power systems

In this work, chaos game optimization (CGO), a robust optimization approach, is employed for efficient design of a novel cascade controller for four test systems with interconnected power systems (IPSs) to tackle load–frequency control (LFC) difficulties. The CGO method is based on chaos theory principles, in which the structure of fractals is seen via the chaotic game principle and the fractals’ self-similarity characteristics are considered. CGO is applied in LFC studies as a novel application, which reveals further research gaps to be filled. For practical implementation, it is also highly desirable to keep the controller structure simple. Accordingly, in this paper, a CGO-based controller of fractional-order (FO) proportional–integral–derivative–FO proportional–integral (FOPID–FOPI) controller is proposed, and the integral time multiplied absolute error performance function is used. Initially, the proposed CGO-based FOPID–FOPI controller is tested with and without the nonlinearity of the governor dead band for a two-area two-source model of a non-reheat unit. This is a common test system in the literature. A two-area multi-unit system with reheater–hydro–gas in both areas is implemented. To further generalize the advantages of the proposed scheme, a model of a three-area hydrothermal IPS including generation rate constraint nonlinearity is employed. For each test system, comparisons with relevant existing studies are performed. These demonstrate the superiority of the proposed scheme in reducing settling time, and frequency and tie-line power deviations.     

Novel chaos game optimization tuned-fractional-order PID fractional-order PI controller for load–frequency control of interconnected power systems

In this work, chaos game optimization (CGO), a robust optimization approach, is employed for efficient design of a novel cascade controller for four test systems with interconnected power systems (IPSs) to tackle load–frequency control (LFC) difficulties. The CGO method is based on chaos theory principles, in which the structure of fractals is seen via the chaotic game principle and the fractals’ self-similarity characteristics are considered. CGO is applied in LFC studies as a novel application, which reveals further research gaps to be filled. For practical implementation, it is also highly desirable to keep the controller structure simple. Accordingly, in this paper, a CGO-based controller of fractional-order (FO) proportional–integral–derivative–FO proportional–integral (FOPID–FOPI) controller is proposed, and the integral time multiplied absolute error performance function is used. Initially, the proposed CGO-based FOPID–FOPI controller is tested with and without the nonlinearity of the governor dead band for a two-area two-source model of a non-reheat unit. This is a common test system in the literature. A two-area multi-unit system with reheater–hydro–gas in both areas is implemented. To further generalize the advantages of the proposed scheme, a model of a three-area hydrothermal IPS including generation rate constraint nonlinearity is employed. For each test system, comparisons with relevant existing studies are performed. These demonstrate the superiority of the proposed scheme in reducing settling time, and frequency and tie-line power deviations.     

灯泡贯流式水轮机(Ⅰ)

本文叙述了灯泡贯流式水轮机的有关技术问题,对于不同的结构设计方案进行了比较,并介绍了灯泡贯流式水轮机的设计和科研要点。     

金属丝电爆炸研究进展-(Ⅰ):真空环境

真空中金属丝电爆炸在Z箍缩等离子体、X射线源等有重要应用,特别是纳秒脉冲下金属单丝的电爆炸行为是丝阵Z箍缩的最初始阶段,对丝阵Z箍缩内爆辐射特性有重要影响,因而受到特别关注。目前,利用高时空分辨的等离子体诊断系统和数值模拟手段,真空环境中金属丝电爆炸的研究已在实验诊断、调控方法、理论模型等方面取得了许多重要研究成果。在介绍发展历史的基础上,主要针对真空环境中纳秒脉冲下金属单丝电爆炸的相关研究,描述了金属丝电爆炸的基本特性,总结了电参数和丝参数对电爆炸特性的影响规律,分析了提高金属丝中沉积能量以实现金属丝汽化的调控方法,并综述了数值模拟中电爆炸丝状态方程、输运参数和磁流体模型等的主要进展,最后指出了研究面临的挑战和未来发展的方向,对今后继续深入开展该领域的研究工作具有一定的借鉴意义。     

挤包高压直流电缆的质量控制:采用低频耐压试验检测电缆的关键缺陷(英文)

The main purpose of the work presented here is to evaluate different methods for quality control of polymeric insulated HVDC cables.The insight gained can be used to evaluate proposed test methods for quality assurance of long lengths of polymer insulated power cables.Laboratory experiments were performed using both Rogowski shaped test objects and model cables,insulated with XLPE containing imbedded spherically shaped particles.Tests were performed by stressing the test object with AC(50 Hz),VLF(0.1 Hz) and DC voltages and measuring time to breakdown at the different voltages.The slope of the voltage-time curve for 0.1 and 50 Hz were found to be parallel showing higher breakdown strength for 0.1 Hz than 50 Hz.The number of periods to breakdown is somewhat higher for 0.1 Hz than for 50 Hz.The breakdown strength for DC was much higher than for both AC 50 Hz and 0.1 Hz.The results indicate that the VLF test voltage needs to be 2 to 3 times higher than at 50 Hz power frequency in order to eliminate the same defects within a comparable time.     

A current-based model of the static synchronous series compensator (SSSC) for Newton–Raphson power flow

In this paper, a new approach to modeling a static synchronous series compensator (SSSC) for power-flow calculations by applying the Newton–Raphson method is presented. This new approach differs from known methods in terms of the interpretation of the device's branch. It is considered on the basis of its current and is therefore denoted as a current-based model of an SSSC. This approach might in principle be applicable also for other FACTS devices (i.e., UPFC, IPFC, GUPFC). In the paper, the current-based model of an SSSC is presented as the models of this device have difficulties with convergence in power-flow calculations and there are very few references covering these topics. First, the basic features of an SSSC are presented, as it is the basis for the current-based model that is incorporated into the Newton–Raphson load-flow model. The results of the tests at the IEEE 57-bus system are discussed in detail and compared with the existing injection SSSC load-flow model [X.P. Zhang, Advanced modeling of the multicontrol functional static synchronous series compensator (SSSC) in Newton power flow, IEEE Trans. Power Syst. 18 (November (4)) 2003].     

设备综合管理工程研究(Ⅰ)

本文作为设备综合管理工程研究的上篇,首先介绍设备综合管理工程的发展进程,大致分为事后维修阶段、预防维修阶段、生产维修阶段、维修预防阶段和全面综合管理阶段,之后阐述了设备综合管理工程的主要任务。     

低压电器的计算机辅助设计(Ⅰ)

综述了国内外低压电器计算机辅助设计(CAD)的发展动态,介绍了计算机在低压断路器、熔断器、接触器和电磁铁等特性计算和优化设计方面的应用,以及计算机交互式绘图功能在电器结构设计中所起的作用,提出了国内开展低压电器CAD工作的建议。