Transmission Network Expansion Planning Considering Optimal Allocation of Series Capacitive Compensation and Active Power Losses

This paper presents a modeling and solution approach to the static and multistage transmission network expansion planning problem considering series capacitive compensation and active power losses. The transmission network expansion planning is formulated as a mixed integer nonlinear programming problem and solved through a highly efficient genetic algorithm. Furthermore, the Villasana Garver’s constructive heuristic algorithm is implemented to render the configurations of the genetic algorithm feasible. The installation of series capacitive compensation devices is carried out with the aim of modifying the reactance of the original circuit. The linearization of active power losses is done through piecewise linear functions. The proposed model was implemented in C++ language programming. To show the applicability and effectiveness of the proposed methodology several tests are performed on the 6-bus Garver system, the IEEE 24-bus test system, and the South Brazilian 46-bus test system, presenting costs reductions in their multi-stage expansion planning of 7.4%, 4.65% and 1.74%, respectively.

Optimal reactive power dispatch using a novel optimization algorithm

The problem of optimal reactive power dispatch (ORPD) is one of the most popular and widely discussed problem in power system engineering all over the world. Optimal reactive power dispatch is one of the sub-problems of the optimal power flow which is complex and nonlinear problem, which can be formulated as both single- and multi-objective. In this paper, the problem has been formulated as a single-objective problem to minimize the active power losses in the transmission lines. A recently proposed powerful and reliable meta-heuristic algorithm known as the JAYA algorithm has been applied to solve the ORPD problem. The algorithm has been applied on the standard IEEE 14, 30, 57 and 118 bus systems. The simulation results using the proposed algorithm when compared with the results from other algorithms and few others reported in the literature prove that the JAYA algorithm is the most superior among all.

ENERGY SAVING BY REPLACING UNLOADED ENGINES OF NON-STANDARD EQUIPMENT FOR ROLLING STOCK REPAIR

It is established that at various technological processes at repair of a rolling stock of railways electric drives of the universal non-standard equipment can constantly work in essentially underloaded mode that leads to deterioration of their power indicators. The aim of the work is to quantify the reduction of active power losses when replacing constantly underloaded asynchronous motors of unregulated electric drives of universal non-standard technological equipment used in the repair of railway rolling stock with less powerful ones. In this work, the subject of research are the motors of electric drives of this equipment. The analysis of technological processes at repair of a rolling stock, technical characteristics of the specified equipment is carried out and the conclusion is accepted that first of all it is expedient to investigate efficiency of replacement on the equipment of the established engine on less powerful at carrying out at the specialized enterprises of such technological processes warehouse (wheel pairs, traction motors, auxiliary electric machines, frames of rolling stock carts, etc.). The load of the electric motors of transport trolleys of equipment is proposed to be defined as the ratio of the weight of a large unit of electric locomotive, diesel locomotive, electric train and other types of rolling stock to the carrying capacity of universal non-standard equipment of transport trolley. The term "universal" equipment is introduced in the work, which means equipment for performing a certain technological process in the repair of various large units of different types of rolling stock, as well as "specialized enterprise" specializing in the repair of rolling stock, large units which weigh significantly less, than the load-lifting capacity of the transport cart of the equipment. Therefore, the motors of electric drives of universal equipment at these enterprises are constantly operating underloaded. Also actions for quantitative assessment and reduction of active power losses in the electric drive motor are offered.

A Phase Generation Shifting Algorithm for Prosumer Surplus Management in Microgrids using Inverter Automated Control

Four-wire low voltage microgrids supply one-phase consumers with continuously changing electricity demand. For addressing climate change concerns, governments implemented incentive schemes for residential consumers, encouraging the installation of home PV panels for covering self-consumption needs. In the absence of sufficient storage capacities, the surplus is sold back by these entities, called prosumers, to the grid operator or in local markets, to other consumers. While these initiatives encourage the proliferation of green energy resources, and ample research is dedicated to local market designs for prosumer-consumer trading, the main concern of distribution network operators is the influence of power flows generated by prosumer surplus injection on the operating states of microgrids. The change in power flow amount and direction can greatly influence the economic and technical operating conditions of radial grids. This paper proposes a metaheuristic algorithm for prosumer surplus management that optimizes the power surplus injections using the automated control of three-phase inverters, with the aim of improving the active power losses and balancing the phase voltage profiles. A case study is performed on two real distribution networks with distinct layouts and load profiles and the algorithm shows its efficiency in both scenarios.

Optimal Rescheduling of the Additional Reactive Power Source Selected in a Backbone Network to a Distribution Network

An additional (generation) source of reactive power may be required in a backbone network node (𝑈௡ ≥ 220 𝑘𝑣) which has a heavy reactive load. When solving this problem, in a technical-economic sense, it is advisable to place this additional source of reactive power not in the mentioned node of a backbone network, but in the nodes of a distribution network (𝑈௡ ≤ 110 𝑘𝑣) connected to this node. This problem specifically involves: optimal rescheduling of total power of the additional reactive power source selected according to a voltage criterion in a backbone network node between the distribution network nodes connected to this node. The relevant optimization equations created in the article and the obtained mathematical model allow us to solve this problem effectively and successfully. The condition for optimality here implies the best economic returns, while the objective function is to minimize active power losses caused by nodal reactive powers. That was why we used the economic criterion as the main criterion in solving this problem.

PARAMETRIC OPTIMIZATION OF OPERATING MODES OF BULK ELECTRICAL NETWORKS BY CRITERIA ACTIVE POWER LOSSES

It is shown that the use of controlled shunt reactors enables, based on ultra-high voltage transmission lines, to create a controlled generation of new generation FACTS types that meet the requirements of modern power systems and combinations. Typical modes of operation of the high-voltage power line with installed controlled shunt reactors are analyzed. The efficiency of the use of controlled shunt reactors as measures of transverse compensation in ultrahigh voltage transmission lines is shown. The article shows that due to a smooth change in the consumption of excess reactive power of the transmission line, the normalization of the voltage values is achieved, and, accordingly, the total power losses are reduced. Ref. 9, fig. 3, tables 3.

A Novel Analytical Approach for Optimal Placement and Sizing of Distributed Generations in Radial Electrical Energy Distribution Systems

Considering the strong influence of distributed generation (DG) in electric distribution systems and its impact on network voltage losses and stability, a new challenge has appeared for such systems. In this study, a novel analytical algorithm is proposed to distinguish the optimal location and size of DGs in radial distribution networks based on a new combined index (CI) to reduce active power losses and improve system voltage profiles. To obtain the CI, active power losses and voltage stability indexes were used in the proposed approach. The CI index with sensitivity analysis was effective in decreasing power losses and improving voltage stability. Optimal DG size was determined based on a search algorithm to reduce active power losses. The considered scheme was examined through IEEE 12-bus and 33-bus radial distribution test systems (RDTS), and the obtained results were compared and validated in comparison with other available methods. The results and analysis verified the effectiveness of the proposed algorithm in reducing power losses and improving the distribution system voltage profiles by determining the appropriate location and optimal DG size. In IEEE 12 and 33 bus networks, the minimum voltage increased from 0.9434 p.u and 0.9039 p.u to 0.9907 p.u and 0.9402 p.u, respectively. Additionally, the annual cost of energy losses decreased by 78.23% and 64.37%, respectively.

Assessment of Daily Cost of Reactive Power Procurement by Smart Inverters

The reactive power control mechanisms at the smart inverters will affect the voltage profile, active power losses and the cost of reactive power procurement in a different way. Therefore, this paper presents an assessment of the cost–benefit relationship obtained by enabling nine different reactive power control mechanisms at the smart inverters. The first eight reactive power control mechanisms are available in the literature and include the IEEE 1547−2018 standard requirements. The ninth control mechanism is an optimum reactive power control proposed in this paper. It is formulated to minimise the active power losses of the network and ensure the bus voltages and the reactive power of the smart inverter are within their allowable limits. The Vestfold and Telemark distribution network was implemented in DIgSILENT PowerFactory and used to evaluate the reactive power control mechanisms. The reactive power prices were taken from the default payment rate document of the National Grid. Simulation results demonstrate that the optimal reactive power control mechanism provides the best cost–benefit for the daily steady-state operation of the network.