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.

Intelligent Reflecting Surface Assisted Transmission Optimization Strategies in Wireless Networks

Wireless Power Transfer(WPT)technology can provide real-time power for many terminal devices in Internet of Things(IoT)through millimeterWave(mmWave)to support applications with large capacity and low latency.Although the intelligent reflecting surface(IRS)can be adopted to create effective virtual links to address the mmWave blockage problem,the conventional solutions only adopt IRS in the downlink from the Base Station(BS)to the users to enhance the received signal strength.In practice,the reflection of IRS is also applicable to the uplink to improve the spectral efficiency.It is a challenging to jointly optimize IRS beamforming and system resource allocation for wireless energy acquisition and information transmission.In this paper,we first design a Low-Energy Adaptive Clustering Hierarchy(LEACH)clustering protocol for clustering and data collection.Then,the problem of maximizing the minimum system spectral efficiency is constructed by jointly optimizing the transmit power of sensor devices,the uplink and downlink transmission times,the active beamforming at the BS,and the IRS dynamic beamforming.To solve this non-convex optimization problem,we propose an alternating optimization(AO)-based joint solution algorithm.Simulation results show that the use of IRS dynamic beamforming can significantly improve the spectral efficiency of the system,and ensure the reliability of equipment communication and the sustainability of energy supply under NLOS link.

Distributionally Robust Co-optimization of Transmission Network Expansion Planning and Penetration Level of Renewable Generation

Transmission network expansion can significantly improve the penetration level of renewable generation.However,existing studies have not explicitly revealed and quantified the trade-off between the investment cost and penetration level of renewable generation.This paper proposes a distributionally robust optimization model to minimize the cost of transmission network expansion under uncertainty and maximize the penetration level of renewable generation.The proposed model includes distributionally robust joint chance constraints,which maximize the minimum expectation of the renewable utilization probability among a set of certain probability distributions within an ambiguity set.The proposed formulation yields a twostage robust optimization model with variable bounds of the uncertain sets,which is hard to solve.By applying the affine decision rule,second-order conic reformulation,and duality,we reformulate it into a single-stage standard robust optimization model and solve it efficiently via commercial solvers.Case studies are carried on the Garver 6-bus and IEEE 118-bus systems to illustrate the validity of the proposed method.

Optimal and constant power allocation for joint transmission in HetNet

This paper investigates the power allocation issues for joint transmission in heterogeneous network （HetNet）, which is characterized by severe cross-tier interference. The optimization problem of maximizing the HetNet throughput is formulated. The original problem turns out to be a non-convex problem, the global optima of which cannot be obtained by conventional optimization methods. This paper develops a novel method to achieve the global optima by tuming the original problem into quasi-convex problem. In addition, this paper considers a constant power allocation scheme, as a tradeoff between the system throughput and computational complexity. Based on duality gap theory, the bound of constant power allocation scheme is mathematically derived. Numerical results under different system parameters indicate that both the proposed schemes outperform conventional interference coordination schemes.

A Scenario-Based Robust Transmission Network Expansion Planning Method for Consideration of Wind Power Uncertainties

This paper uses a novel scenario generation method for tackling the uncertainties of wind power in the transmission network expansion planning(TNEP)problem.A heuristic moment matching(HMM)method is first applied to generate the typical scenarios for capturing the stochastic features of wind power,including expectation,standard deviation,skewness,kurtosis,and correlation of multiple wind farms.Then,based on the typical scenarios,a robust TNEP problem is presented and formulated.The solution of the problem is robust against all the scenarios that represent the stochastic features of wind power.Three test systems are used to verify the HMM method and is compared against Taguchi’s Orthogonal Array(OA)method.The simulation results show that the HMM method has better performance than the OA method in terms of the trade-off between robustness and economy.Additionally,the main factors influencing the planning scheme are studied,including the number of scenarios,wind farm capacity,and penalty factors,which provide a reference for system operators choosing parameters.

Impact of the penetration of distributed generation on optimal reactive power dispatch

Optimal reactive power dispatch(ORPD)is a complex and non-linear problem,and is one of the sub-problems of optimal power flow(OPF)in a power system.ORPD is formulated as a single-objective problem to minimize the active power loss in a transmission system.In this work,power from distributed generation(DG)is integrated into a conventional power system and the ORPD problem is solved to minimize transmission line power loss.It proves that the application of DG not only contributes to power loss minimization and improvement of system stability but also reduces energy consumption from the conventional sources.A recently proposed meta-heuristic algorithm known as the JAYA algorithm is applied to the standard IEEE 14,30,57 and 118 bus systems to solve the newly developed ORPD problem with the incorporation of DG.The simulation results prove the superiority of the JAYA algorithm over others.The respective optimal values of DG power that should be injected into the four IEEE test systems to obtain the minimum transmission line power losses are also provided.

最大化光伏并网的发输电联合系统协调规划方法

针对光伏的强不确定性和大规模并网给电网带来的问题,需要通过增加新的可调度机组和输电线路来进行系统升级。对此提出了一种发电和输电联合优化规划模型,以最大化地提高光伏发电容量规模。通过Benders分解方法来解决该模型的计算复杂性。该模型的解决方案进一步确定了最优太阳能光伏规模和位置,以及潜在的所需光伏的能量削减。对六节点系统算例的分析表明,在考虑和不考虑光伏并网的情况下,所提出的联合优化规划比发电和输电的单独规划更有效。

能量高效的无线传感器网络传输可靠性研究

在保证数据传输可靠性的前提下节省网络能量开销是无线传感器网络应用研究所必须面对的重要课题。通过实验研究,发现了无线传感器网络的通信链路存在着高丢失率、非对称性等特点;通过最优化理论推导出端到端链路中各个节点的优化发射功率;由此提出将节点的优化发射功率和路由度量相结合的OPAETX联合优化方法。利用仿真试验评价OPAETX算法的性能,仿真试验结果表明使用该联合优化方法,在保证端到端的可靠性的前提下节省了网络的能量。

三线圈结构的无线电能传输系统优化设计与分析

针对增大或提高传输距离固定的无线电能传输系统的传输功率和系统效率问题,提出一种三线圈(含中继线圈)结构的无线电能传输系统综合优化分析方法。根据系统的精确建模分析,寻求系统最大功率和效率的阻抗匹配条件,通过不断变换中继线圈参数(匝数、位置),在满足阻抗匹配的条件下建立负载接入系统时最大理论功率或最大理论效率点的集合。在此基础上,根据系统的功率、效率、负载等实际需求约束,在集合中优化寻找最优的系统传输效率和功率,实现对系统传输效率和功率的优化。理论分析和实验均证明了该方法的正确性和有效性。

Transmission congestion management considering multiple and optimal capacity DGs

Transmission congestion management became a grievous issue with the increase of competitiveness in the power systems. Competitiveness arises due to restructuring of the utilities along with the penetration of auxiliary services. The present study depicts a multi objective technique for achieving the optimal capacities of distributed generators(DG) such as solar, wind and biomass in order to relieve congestion in the transmission lines. Objectives like transmission congestion, real power loss, voltages and investment costs are considered to improve the technical and economical performances of the network. Multi objective particle swarm optimization algorithm is utilized to achieve the optimal sizes of unity power factor DG units.The insisted methodology is practiced on IEEE-30 and IEEE-118 bus systems to check the practical feasibility.The results of the proposed approach are compared with the genetic algorithm for both single and multi-objective cases. Results revealed that the intimated method can aid independent system operator to remove the burden from lines in the contingency conditions in an optimal manner along with the improvement in voltages and a reduction in real power losses of the network.