Allocation of fixed costs in distribution networks with distributed generation

In this paper, we propose a method for the allocation of fixed (capital and nonvariable operation and maintenance) costs at the medium voltage (MV) distribution level. The method is derived from the philosophy behind the widely used MW-mile methodology for transmission networks that bases fixed cost allocations on the "extent of use" that is derived from load flows. We calculate the "extent of use" by multiplying the total consumption or generation at a busbar by the marginal current variations, or power to current distribution factors (PIDFs) that an increment of active and reactive power consumed, or generated in the case of distributed generation, at each busbar, produces in each circuit. These PIDFs are analogous to power transfer distribution factors (PTDFs). Unlike traditional tariff designs that average fixed costs on a per kWh basis across all customers, the proposed method provides more cost-reflective price signals and helps eliminate possible cross-subsidies that deter profitable (in the case of competition) or cost-effective (in the case of a fully regulated industry) deployment of DG by directly accounting for use and location in the allocation of fixed costs. An application of this method for a rural radial distribution network is presented.     

挪威输电定价机制分析及借鉴意义

输电作为电力市场中的关键环节,其定价机制也是我国当前电力市场改革的重点任务。合理的输电定价机制能为输电用户提供有效的价格信号,促进电力资源的优化配置。本文对挪威输电定价机制进行深入研究,介绍了定价的基本思路,分析了输电过网费的组成部分,可变费用、固定费用的影响要素。其中,可变费用方面重点介绍基于边际网损率的可变费率的计算及各节点的边际网损率调整前后对可变费用的影响;固定费用方面重点介绍减免标准及减免程度,分析有无减免措施情况下对负荷侧承担固定费用的影响。通过7节点模型对挪威输电定价机制引导并网用户的发电、用电行为及投资的有效性进行分析。挪威输电定价机制能有效引导电源、负荷合理布局,可为我国输配电定价提供借鉴。     

Separation of power systems into a unique set of zones based on transmission usage of network tariffs and transmission loss tariffs

Transmission usage of network tariffs (TUNT) and transmission loss tariffs (TLT) are among the most important pricing mechanisms that are utilized to recover main transmission costs in today’s electricity markets. Separation of entire power network into different tariff zones is a common approach which simplifies the tariff mechanisms particularly for large power systems. Zonal distribution of nodal tariffs that is calculated based on classical weighted-average procedures can be different given the difference between the calculation methodologies of the TUNTs and TLTs. However, correlation between nodal TUNTs and TLTs can be very strong, particularly when they are determined based on marginal pricing methodologies. This paper proposes an approach which separates a power system into a unique set of zones considering the nodal distribution of TUNTs and TLTs. In this approach, mismatches between the nodal elements of TUNTs and TLTs zones are iteratively eliminated until a unique zonal tariff sets are created. Application of the proposed zoning approach is discussed on the zonal TUNTs and TLTs of the Turkish power system. Numerical verification of the proposed zoning methodology is made with the IEEE 24 Bus System. Unique set of tariff zones can be represented on a map which will provide significant and consistent indication about the transmission enforcement requirements of the network in a simplest and efficient manner.     

考虑风光无功调节的配电网分布式电源双层规划

分布式电源(distributed generation, DG)作为配电网运行优化中关键一环,其合理的调控策略可以有效提高新能源渗透,减少电压波动,并降低网络损耗,因此在规划阶段,应充分考虑DG无功出力,最大限度发挥DG互补能力。本文建立了以经济性和稳定性为目标的含DG控制模型的双层配电网规划模型,在上层中以最小年综合费用为目标对DG位置容量进行决策,下层计算电压偏差最小化时的DG控制策略,使用粒子群算法对该模型进行分层求解,求得年费用和电压波动最优的DG安装位置和容量,并在IEEE 33节点算例中验证了该模型能够有效提高源网协同控制能力,发挥DG调节作用。     

Transmission Use of System Charges Under Future GB Power System Scenarios

If transmission charges are to reflect costs, they should be affected by the location of demand and generation. This paper describes the investment cost-related pricing (ICRP) methodology used to calculate transmission charges in Great Britain (GB), which is based on the marginal investment cost of additional demand or generation, using a dc load flow transport model. We apply this existing method to calculate charges for the Supergen FutureNet scenarios for 2020. This study highlights the sensitivities in charges for use of the transmission system arising from plausible demand and generation developments. The changes in tariffs will present financial challenges for system users in some areas. The objective of the work presented is to illustrate the sensitivity of the charges produced by this methodology to changes in demand, generation, and network topology rather than compare alternative pricing approaches. The conclusion drawn is that the ICRP system pricing method may be suitable in future years but only with some important issues investigated and resolved.     

基于遗传-蚁群算法的交直流配电网分布式电源优化配置

随着分布式电源（distributed generation，DG）受到广泛的关注与研究，分布式电源接入交直流配电网的规划问题日益突出。该文在分布式电源选址定容阶段充分考虑不同类型DG和负荷的时序特性，以DG运维费用、DG投资年等效费用、系统网络损耗费用、燃料费用、污染赔偿费用、环保补贴综合最小作为目标函数，同时加入电压、功率等约束条件，建立了DG的选址定容模型。根据遗传、蚁群算法各自的优劣势，提出了运用遗传-蚁群复合算法求解该优化模型。最后以改进的IEEE-33节点配电网作为算例，验证了所提模型的合理性及算法的有效性。     

Electricity transmission pricing: Tracing based point-of-connection tariff

Point-of-connection (POC) scheme of transmission pricing in decentralized markets charges the participants a single rate per MW depending on their point-of-connection. Use of grossly aggregated postage stamp rates as POC charges fails to provide appropriate price signals. The POC tariff based on distribution of network sunk costs by employing conventional tracing assures recovery of sunk costs based on extent of use of network by participants. However, the POC tariff by this method does not accommodate economically efficient price signals which correspond to marginal costs. On the other hand, the POC tariff, if made proportional to marginal costs alone, fails to account for sunk costs and extent of use of network. This paper overcomes these lacunae by combining the above stated desired objectives under the recently proposed optimal tracing framework. Since, real power tracing problem is amenable to multiple solutions, it is formulated as linearly constrained optimization problem. By employing this methodology, consideration of extent of network use and sunk cost recovery are guaranteed, while objective function is designed such that the spatial pattern of price signals closely follows the pattern of scaled locational marginal prices. The methodology is tested on IEEE 30 bus system, wherein average power flow pattern is established by running various simulation states on congested and un-congested network conditions.     

Comparison of optimal DG allocation methods in radial distribution systems based on sensitivity approaches

Integration of renewable energy based distributed generation (DG) units provides potential benefits to conventional distribution systems. The power injections from renewable DG units located close to the load centers provide an opportunity for system voltage support, reduction in energy losses, and reliability improvement. Therefore, the location of DG units should be carefully determined with the consideration of different planning incentives. This paper presents a comparison of novel, combined loss sensitivity, index vector, and voltage sensitivity index methods for optimal location and sizing of distributed generation (DG) in a distribution network. The main contribution of the paper is: (i) location of DGs based on existing sensitivity methods, (ii) proposing combined power loss sensitivity based method for DG location, (iii) modified Novel method for DG location, (iv) comparison of sensitivity methods for DG location and their size calculations, and (v) cost of losses and determining cost of power obtained from DGs and the comparison of methods at unity and lagging power factors. The results show the importance of installing the suitable size of DG at the suitable location. The results are obtained with all sensitivity based methods on the IEEE 33-bus and 69-bus systems.     

基于配电网节点边际容量成本和时序特性的分布式电源规划

配电网的边际容量成本表述了负荷的增加或分布式电源(DG)接入配电网中引起供电设备所需容量的变化,从而引起的供电投资成本的变化。本文针对开环运行的配电网,通过灵敏度法构建灵敏度系数矩阵,对配电网的节点边际容量成本(LMCC)进行计算,并根据实际情况考虑LMCC的变化,将DG效益评估分为用户自备DG和电力部门DG配置。重点讨论电力部门DG配置情况下多类型DG选址定容的规划,并考虑了多类型DG和负荷的时序特性。最后运用MATLAB仿真软件在IEEE33节点配电网系统中进行了LMCC数值计算,利用粒子群算法进行了考虑时序特性的DG规划,并验证了模型和方法的合理性。     

Uniform Marginal Pricing for the Remuneration of Distribution Networks

A new method for distribution access via uniform pricing for the remuneration of distribution networks is presented. The proposed approach merges in a unified framework the investments, the optimal network operation requirements, the effect of the price elasticity of demand, and the application of hourly pricing for demand side management purposes. Hourly uniform marginal prices—understood as tariffs of use of the network—are obtained from maximum social welfare condition sending efficient signals to the utility and consumers, related to the optimal operation of the grid and use of the energy at peak and valley hours. This method is used in the context of a Performance Based Ratemaking regulation to get model companies from operational optimized real networks. Capital fees are integrated in the marginal tariff of use, by means of the New Replacement Value concept, broadly used in yardstick competition. The model is stated as a mixed-integer linear optimization problem suitable to be solved through well-known linear programming tools. The methodology has been successfully tested in a 42-bus test distribution network.     

基于输配电价的用户定价策略选择模型的构建

近期,国家发展和改革委员会下发了第三监管周期省级电网输配电价,并调整了两部制电价执行的范围,对符合条件的用户赋予了选择执行单一制、两部制输配电价定价策略的选择权,而如何选择定价策略可以更具备经济性,成为困扰用电客户的难题。为此,基于当前的输配电价及相关电费计算规则,分析影响用户定价策略选择的关键因素,定义相关参数作为变量,根据现行输配电价计算定价策略经济性临界曲线,构建了一套输配电价定价策略比选模型,并通过典型用户对模型进行了验证,为用户科学合理选择输配电价定价策略提供了一套可行的方案。     

分布式电源接入配电网的经济效益及电压稳定性

借助于回归分析方法将配电网和主网联系起来,基于实时电价理论构建了DG接入配电网的经济效益及配电网电压稳定性分析模型。以IEEE30系统节点8下属配电网接入4个DG为例,定量分析了6个典型日内DG接入前后主配网经济效益及配电网电压稳定性。结果表明：DG合理接入后,终端电力用户的支付电价下降,能够有效消除可能出现的输电阻塞;主配网网损率明显下降,提高了电力输送效率;主配网购电成本显著下降,提高了市场运行效率;高峰时段DG因相对低成本而全额发电,能获得较高的利润;配电网电压稳定性明显增强。随着分布式发电技术的成熟,其成本将会不断下降,DG会因具有成本优势和地理位置优势而成为传统电网的有效补充。     

考虑网损的配电节点电价模型及迭代计算方法

在分布式电源装机容量快速增长的背景下，建立本地电力市场可促进分布式机组出力的消纳和配电网的优化运行。文章提出了适用于本地市场竞价出清的配电节点电价（distribution locational marginal pricing，DLMP）模型，将其分解为有功价格分量、无功价格分量、网损价格分量、电压支撑价格分量以及阻塞价格分量，可量化各分量对节点电价的贡献。同时采用迭代算法对该模型进行求解，通过市场出清模型与交流潮流的迭代计算克服线性化节点电价模型对预设网损因子的依赖。通过对IEEE 33节点配电系统的仿真分析，验证了所提模型的有效性和所提算法的准确性。     

基于SNOP的柔性配电网中分布式电源最大准入容量计算

分布式电源高比例接入配电网,将会引起配电网潮流越限等问题,影响配电网安全运行。基于智能软开关的柔性配电网为提高分布式电源消纳能力提供了新的思路。智能软开关的动态双向功率调节能力,有助于改善配电网中电压瓶颈节点和传输容量瓶颈支路的运行状态,实现全网潮流主动协同管理,从而提高柔性配电网中分布式电源准入容量。首先建立了柔性配电网中分布式电源最大准入容量模型,基于配电系统的多节点特性,该模型属于高维非线性优化问题。然后根据实际场景和参数设置的不同,分为传统配电网中分布式电源固定节点位置、柔性配电网中分布式电源固定节点位置、柔性配电网中分布式电源自由接入3种情况进行分析,并采用多种群遗传算法求解得到全局最优解。最后使用IEEE 33节点配电系统进行算例分析,结果验证了柔性配电网中智能软开关的应用对分布式电源接入能力的提升作用。所提方法在获得柔性配电网中分布式电源准入容量的同时,可从规划角度得到分布式电源接入的最优容量和位置。     

Optimal placement of DG in radial distribution systems based on new voltage stability index under load growth

This paper presents a comparison of Novel Power Loss Sensitivity, Power Stability Index (PSI), and proposed voltage stability index (VSI) methods for optimal location and sizing of distributed generation (DG) in radial distribution network. The main contribution of the paper is: (i) optimal placement of DGs based on Novel Power Loss Sensitivity and PSI methods, (ii) proposed voltage stability index method for optimal DG placement, (iii) comparison of sensitivity methods for DG location and their size calculations, (iv) optimal placement of DG in the presence of load growth, (v) impact of DG placement at combined load power factor, (vii) impact of DG on voltage stability margin improvement. Voltage profile, the real and reactive powers intake by the grid, real and reactive power flow patterns, cost of energy losses, savings in cost of energy loss and cost of power obtained from DGs are determined. The results show the importance of installing the suitable size of DG at the suitable location. The results are obtained with all sensitivity based methods on the IEEE 12-bus, modified 12-bus, 69-bus and 85-bus test systems.     

基于自适应遗传算法的配电网DG选址与定容

以配电网规划投资为考虑因素,建立了含分布式电源(DG)的配电网规划经济性模型,以折算到每年的DG的投资运行费用、线路运行费用及引入DG后购电费用最小为目标函数,采用自适应遗传算法解决DG布点规划问题。通过对某地35节点低压配电网算例进行仿真计算,验证了本文算法的有效性,并得到了DG较为合理的安装位置和接入容量。     

A combination of genetic algorithm and particle swarm optimization for optimal DG location and sizing in distribution systems

Distributed generation (DG) sources are becoming more prominent in distribution systems due to the incremental demands for electrical energy. Locations and capacities of DG sources have profoundly impacted on the system losses in a distribution network. In this paper, a novel combined genetic algorithm (GA)/particle swarm optimization (PSO) is presented for optimal location and sizing of DG on distribution systems. The objective is to minimize network power losses, better voltage regulation and improve the voltage stability within the frame-work of system operation and security constraints in radial distribution systems. A detailed performance analysis is carried out on 33 and 69 bus systems to demonstrate the effectiveness of the proposed methodology.     

配电网节点边际容量成本及应用

分析了现有配电网边际容量成本的不足。通过将支路增量成本合理地分摊到各负荷节点,提出配电网节点边际容量成本（LMCC）的概念,反映未来各节点负荷占用供电容量的成本。LMCC基于配电网供电容量的利用现状和负荷增长趋势,并不依赖于未来规划网架,因而具有较强的可操作性。最后,讨论了LMCC在配电网规划、容量定价、需求侧管理和分布式电源接入中的应用前景。     

基于配电网节点边际容量成本的分布式电源规划

分布式电源(DG)接入配电网可能导致现有供电设备得不到充分利用,产生沉没成本.引入配电网节点边际容量成本(LMCC)以反映各节点容量的紧张程度,同时给出DG单位容量成本的计算方法.在此基础上,以DG单位容量成本小于接入点的边际容量成本作为DG接入的判据,提出一种规划DG位置和容量的新方法.算例结果验证了方法的可行性.     

Hybrid optimization implemented for distributed generation parameters in a power system network

This paper presents a novel hybrid optimization algorithm for optimizing the Distributed Generation (DG) parameters in deregulated power system which improves the stability, reduces the losses and also increases the cost of generation. This Hybrid algorithm which includes Fuzzy-Genetic Algorithm (FGA) is used to optimize the various DG parameters simultaneously. The various parameters taken into consideration are their type, location and size of the DG devices. The simulation was performed on a distribution system and modeled for steady state studies. The optimization results are compared to the solution given by another search method like Genetic Algorithm (GA) and Micro Genetic Algorithm (MGA). The results reveal the benefits of the proposed method, for solving simultaneous combinorial problems of DG devices in a power system network.