Research on Coordinated Development and Optimization of Distribution Networks at All Levels in Distributed Power Energy Engineering

The uncertainty of distributed generation energy has dramatically challenged the coordinated development of distribution networks at all levels.This paper focuses on the multi-time-scale regulation model of distributed generation energy under normal conditions.The simulation results of the example verify the self-optimization characteristics and the effectiveness of real-time dispatching of the distribution network control technology at all levels under multiple time scales.

Research on power electronic transformer applied in AC/DC hybrid distribution networks

The AC/DC hybrid distribution network is one of the trends in distribution network development, which poses great challenges to the traditional distribution transformer. In this paper, a new topology suitable for AC/DC hybrid distribution network is put forward according to the demands of power grid, with advantages of accepting DG and DC loads, while clearing DC fault by blocking the clamping double sub-module(CDSM) of input stage. Then, this paper shows the typical structure of AC/DC distribution network that is hand in hand. Based on the new topology, this paper designs the control and modulation strategies of each stage, where the outer loop controller of input stage is emphasized for its twocontrol mode. At last, the rationality of new topology and the validity of control strategies are verified by the steady and dynamic state simulation. At the same time, the simulation results highlight the role of PET in energy regulation.

Identification of Type of a Fault in Distribution System Using Shallow Neural Network with Distributed Generation

A distributed generation system(DG)has several benefits over a traditional centralized power system.However,the protection area in the case of the distributed generator requires special attention as it encounters stability loss,failure re-closure,fluctuations in voltage,etc.And thereby,it demands immediate attention in identifying the location&type of a fault without delay especially when occurred in a small,distributed generation system,as it would adversely affect the overall system and its operation.In the past,several methods were proposed for classification and localisation of a fault in a distributed generation system.Many of those methods were accurate in identifying location,but the accuracy in identifying the type of fault was not up to the acceptable mark.The proposed work here uses a shallow artificial neural network(sANN)model for identifying a particular type of fault that could happen in a specific distribution network when used in conjunction with distributed generators.Firstly,a distribution network consisting of two similar distributed generators(DG1 and DG2),one grid,and a 100 Km distribution line is modeled.Thereafter,different voltages and currents corresponding to various faults(line to line,line to ground)at different locations are tabulated,resulting in a matrix of 500×18 inputs.Secondly,the sANN is formulated for identifying the types of faults in the system in which the above-obtained data is used to train,validate,and test the neural network.The overall result shows an unprecedented almost zero percent error in identifying the type of the faults.

Blockchain-Based Power Transaction Method for Active Distribution Network

A blockchain-based power transaction method is proposed for Active Distribution Network(ADN),considering the poor security and high cost of a centralized power trading system.Firstly,the decentralized blockchain structure of the ADN power transaction is built and the transaction information is kept in blocks.Secondly,considering the transaction needs between users and power suppliers in ADN,an energy request mechanism is proposed,and the optimization objective function is designed by integrating cost aware requests and storage aware requests.Finally,the particle swarm optimization algorithm is used for multi-objective optimal search to find the power trading scheme with the minimum power purchase cost of users and the maximum power sold by power suppliers.The experimental demonstration of the proposed method based on the experimental platform shows that when the number of participants is no more than 10,the transaction delay time is 0.2 s,and the transaction cost fluctuates at 200,000 yuan,which is better than other comparison methods.

A Clustering-tree Topology Control Based on the Energy Forecast for Heterogeneous Wireless Sensor Networks

How to design an energy-efficient algorithm to maximize the network lifetime in complicated scenarios is a critical problem for heterogeneous wireless sensor networks (HWSN). In this paper, a clustering-tree topology control algorithm based on the energy forecast (CTEF) is proposed for saving energy and ensuring network load balancing, while considering the link quality, packet loss rate, etc. In CTEF, the average energy of the network is accurately predicted per round (the lifetime of the network is denoted by rounds) in terms of the difference between the ideal and actual average residual energy using central limit theorem and normal distribution mechanism, simultaneously. On this basis, cluster heads are selected by cost function (including the energy, link quality and packet loss rate) and their distance. The non-cluster heads are determined to join the cluster through the energy, distance and link quality. Furthermore, several non-cluster heads in each cluster are chosen as the relay nodes for transmitting data through multi-hop communication to decrease the load of each cluster-head and prolong the lifetime of the network. The simulation results show the efficiency of CTEF. Compared with low-energy adaptive clustering hierarchy (LEACH), energy dissipation forecast and clustering management (EDFCM) and efficient and dynamic clustering scheme (EDCS) protocols, CTEF has longer network lifetime and receives more data packets at base station. © 2014 Chinese Association of Automation.

Incremental cost analysis model of distribution network based on economic dispatch of distributed new-energy storage system

With the implementation of China’s carbon-peaking and carbon-neutrality strategy,new energy will achieve leapfrog growth.Due to the good economics of distributed new-energy generation,it can not only save users’own investment,but also help to achieve local consumption of new energy.However,it will also bring about a series of incremental costs to the power grid.This paper first enumerates the concept,development status and scheduling mode of a distributed new-energy storage system.Based on the above,it establishes a new-energy power generation model and an energy storage system charging and discharging model,and proposes a global optimization scheduling model for a distributed new-energy storage system,considering the time-of-use electricity price and taking the lowest total operating cost of the distributed new-energy power generation system as the objective function.Finally,it proposes a distribution network incremental cost analysis model based on the penetration of distributed new energy.The calculation results show that the incremental cost of grid-connected distributed new energy is 1.0849,1.2585 and 1.3473 yuan/kWh,respectively,which indicates that the global dispatching model can optimize the power consumption structure of a distributed power generation system,and has the function of peak shaving and valley filling,but the incremental cost of the distribution network will also increase.

Strategies Regarding Operating Voltage Levels in Distribution Networks

The power/energy losses reduction in distribution systems is an important issue during planning and operation, with important technical and economical implications. Thus, the energy losses minimization implies not only the technical improvement of the network, through its renewal with the introduction of the technological innovations in the equipment and circuit components as well as the optimal planning of the design and development of the network, but also requires the use of the methods and software tools to facilitate the operation process. The paper presents a strategy for power / energy saving which is replacement of the 6 kV voltage level with 20 kV voltage level. In this line, different urban distribution networks were analyzed using fuzzy techniques for load modeling.

新型电缆贯通供电系统短路特性分析

新型电缆贯通供电系统能够实现长距离输电、减少电分相数目,但两级供电模式将导致该系统结构复杂.为研究电缆贯通供电系统短路特性,首先,建立单位长度的牵引电缆和接触网-钢轨的二端口网络参数,将各个子网络级联等效成1个二端口网络,进而转化为Ⅱ型电路,实现牵引电缆和接触网-钢轨任意长度的分布参数建模;由于接触网短路后导致机车电压下降,基于车网耦合关系采用迭代计算求解短路电流电压,仿真验证计算方法的准确性.最后,解析不同短路类型的电气特性,重点分析分布电容对短路电流、电压的影响.研究结果表明:分布电容会引起短路电流增大,且在不同短路情况下均造成牵引变压器输出电压增加;接触网短路电流由两侧牵引变压器共同提供,距短路点越远提供的电流越少;电缆相间短路对非故障回路机车运行影响最大.

Decentralized Bilateral Risk-based Self-healing Strategy for Power Distribution Network with Potentials from Central Energy Stations

Owing to potential regulation capacities from flexible resources in energy coupling,storage,and consumption links,central energy stations(CESs)can provide additional support to power distribution network(PDN)in case of power disruption.However,existing research has not explicitly revealed the emergency response of PDN with leveraging multiple CESs.This paper proposes a decentralized self-healing strategy of PDN to minimize the entire load loss,in which multi-area CESs’potentials including thermal storage and building thermal inertia,as well as the flexible topology of PDN,are reasonably exploited for service recovery.For sake of privacy preservation,the co-optimization of PDN and CESs is realized in a decentralized manner using adaptive alternating direction method of multipliers(ADMM).Furtherly,bilateral risk management with conditional value-at-risk(CVaR)for PDN and risk constraints for CESs is integrated to deal with uncertainties from outage duration.Case studies are conducted on a modified IEEE 33-bus PDN with multiple CESs.Numerical results illustrate that the proposed strategy can fully utilize the potentials of multi-area CESs for coordinated load restoration.The effectiveness of the performance and behaviors’adaptation against random risks is also validated.

Deployment of wireless sensor network in dispersed renewable energy sources for increasing efficiency of power distribution networks

In this work,a novel performance analysis method for evaluating the robustness of emerging power distribution networks(PDNs),which involve deployable renewable energy sources,is proposed.This is realized with the aid of the outage probability(OP)criterion in the context of cooperative communications,which is widely considered in modern wireless communication systems.The main usefulness of this method is that it allows the involved components to communicate to each-other by means of a robust and flexible wireless sensor network architecture.In this context,any conventional medium voltage(MV)bus of the PDN is represented as a wireless relay node where data signals gathered from each MV bus can be forwarded reliably to a control station for the subsequent processing.The received signals at wireless nodes are decoded and then forwarded to ensure minimal errors and maximal robustness at the receiving site.The considered OP analysis denotes the probability that the power of a received information signal drops below a pre-defined threshold which satisfies the acceptable Quality of Service requirements of a reliable signal reception.To this end,simple closed-form expressions are proposed for the OP of a regenerative cooperative-based PDN in the presence of various multipath fading effects,which degrade information signals during wireless transmission.The offered results are rather simple and provide meaningful insights for the design and deployment of smart grid systems.

含产消者租赁共享储能的主动配电网协同优化决策

共享储能作为一种新兴储能运营模式,在降低产消者投资成本、提高储能利用效率等方面发挥了重要作用。但是,当前产消者彼此间以及其与共享储能运营商之间的复杂交互和利益竞争加剧了主动配电网优化调控的难度。因此,提出一种含产消者租赁共享储能的主动配电网协同优化决策方法。首先,构建了一种考虑配电系统运营商、产消者和共享储能运营商间交互影响的多主体协同交易框架。其次,建立了计及共享储能参与的点对点电力共享交易机制,并据此提出了产消者租赁共享储能的两阶段定价策略,采用议价因子指标量化价格制定过程中各主体的议价能力。然后,建立了基于改进纳什议价的主动配电网博弈优化模型,在指数项中引入议价因子用以设定其在目标中的权重,实现收益的合理分配。最后,采用改进的IEEE 33节点配电系统进行算例仿真,验证了所提方法的有效性。

配电网高比例新能源极限消纳容量精准估计

高比例新能源接入配电网会导致潮流具有不确定性,新能源极限消纳容量估计精准度不高。针对该问题,提出了配电网高比例新能源极限消纳容量精准估计方法。确定反映高比例新能源出力大小和波动特性的物理量,分析不同天气条件下的高比例新能源出力特性。构建高比例新能源接入配电网网络模型,计算当前消纳容量以及高比例新能源接入节点的电压越限风险,将其与设定的电压越限标准阈值对比,得到极限消纳容量精准估计结果。实验结果表明,所提方法估计出的极限消纳容量数值与实验数据之间仅存在最大为200 kVA的误差,说明该方法的估计结果更为精准。

低压分布式光伏调控策略研究及验证

为解决低压分布式光伏接入配电网造成台区过电压、反向重过载等突出问题,本文将有源配电网可调可控能力建设作为配电网高质量发展的重点,基于台区智能融合终端提出了两种调控方法,包括“粗调+细调”群调模式和“粗调+细调”顺控模式,并分析了两种方法各自的优缺点,从仿真测试及现场运行两个纬度,验证了本文所提方法的正确性及可行性,实现了台区过电压问题有效治理,满足台区安全自治需求,具备推广应用价值。所得结果和结论有助于有源配电网设备安全稳定运行。

高比例新能源接入下配电网源荷自动跟踪研究

不可控的幅值突变是导致配电网主机无法精准跟踪源荷信号的主要原因,为解决这个问题,提出高比例新能源接入下配电网源荷自动跟踪方法。根据高比例电量输入比条件确定配电调度参数的取值范围,并联合相关电量传输信号,实现高比例新能源接入下的配电网源荷状态识别。根据配电网源荷阵列的数学表达式,提取源荷基波,确定跟踪向量的取值范围,从而完成高比例新能源接入下配电网源荷的自动跟踪。实验结果表明,应用所提方法可以避免源荷信号在单位传输周期内出现幅值不可控的情况,较好地解决了幅值突变造成的配电网主机无法精准跟踪源荷信号的问题。

Planning Model for Energy Routers Considering Peer-to-Peer Energy Transactions Among Multiple Distribution Networks

A high proportion of renewable energy affects the power quality of distribution networks,and surplus energy will be sold to the upstream grid at a low price.In this paper,considering peer-to-peer energy transactions,the energy router-based multiple distribution networks are analyzed to solve the above problems and realize collaborative consumption of renewable energy.Presently,the investing cost of an energy router is high,and research on the economic operation of energy routers in distribution networks is little.Therefore,this paper establishes a planning model for energy routers considering peer-to-peer energy transactions among distribution networks,and explores the benefits of peer-to-peer energy transactions through energy router based multiple distribution networks.A structure of an energy router suitable for peer-to-peer energy transactions is selected,and a power flow calculation model based on a multilayer structure is established.The energy router’s scheduling model is established,and unique functions of the energy router and revenue of each distribution network are considered.A power flow calculation model based on peer-to-peer interconnection of multiple distribution networks through energy routers is also established.Finally,simulation results verify the effectiveness of the proposed planning model.Results show that peer-topeer energy transaction among distribution networks through energy routers can effectively reduce the comprehensive cost of distribution networks,significantly improve the power quality of the distribution networks,and reduce the impact of power fluctuation on the upstream grid incurred by the distribution network.

分布式电源接入对电力系统稳定性的影响研究

随着新能源技术的快速发展,作为一种环保、经济、高效的发电方式,分布式电源(Distributed Generation,DG)逐渐在电力系统中得到广泛应用。然而,分布式电源的接入对该系统的稳定性产生了复杂影响。文章旨在分析分布式电源接入对电力系统稳定性的影响,探讨其正面效应与潜在问题,并提出了相应的优化策略。

考虑新能源消纳率的主动配电网储能优化配置策略

储能的合理配置不仅可以促进新能源消纳,还可以实现削峰填谷,保障配电网安全、可靠、经济运行。因此提出一种考虑新能源消纳率的储能优化配置策略,构建规划-运行双层模型。上层通过灰狼算法生成储能位置、容量及功率,传递给下层作为新增可调度的储能设备。下层采用基于二阶锥动态潮流的主动配电网经济运行模型求取最低运行总成本,并结合储能投资成本作为适应度函数,反馈给上层引导迭代优化的方向。利用改进的IEEE33节点系统进行算例分析,结果表明:由所提策略计算出的储能最优配置方案,能够在有效提高风、光消纳率的同时提升配电网整体经济性。

配电网调控中新能源接入对通信电源的影响分析

随着全球能源结构的转型和可持续发展战略的实施,风力发电、太阳能发电等新能源发电技术得到了广泛应用。然而,新能源发电的接入对现有的配电网调控系统,特别是通信电源部分产生了显著影响。文章分析了新能源接入对配电网调控中通信电源的影响,提出了相应的应对策略。

分布式能源资源整合与新能源电力市场化营销研究

综合分析了分布式能源资源的特性及挑战,并介绍了微网、虚拟电厂和智能电网等关键技术,探讨了它们在能源领域中的作用与意义;同时,提出了新能源电力市场化运作的核心机制,包括市场化机制与平台的设计、市场化技术工具的应用以及电力交易与结算的运作。通过企业实证案例的分析,验证了分布式能源资源与新能源电力市场化整合在企业电力销售方面的实际意义与效果,对于推动能源领域的可持续发展具有重要的理论与实践价值。

基于NEG-LF信息协调配网网格源荷功率的智能终端设计

随着NEG并网功率不断增大和负荷日益多元化,如何快速协调配网系统源荷功率平衡,实现新能源最大化消纳,已成为亟需解决的问题。为此,首先分析了配网网格特点;其次设计了一种基于配网网格NEG与LF信息的智能终端,给出了其功能、整体构成、供电电源、信息采集与传输方案以及源荷协调策略,以协调网格内源荷功率平衡;最后研制了相关产品,重点做了网格内源荷功率协调测试,并与目前方案进行了对比。结果表明,文中所设计智能终端能够对网格内源荷功率进行可靠协调,实现NEG最大化利用和多方信息共享,推广应用价值高。