Plug-in electric vehicles (PEVs) present environmental and energy security advantages versus conventional gasoline vehicles. In the near future, the number of plug-in electric vehicles will likely grow significantly in the world. Despite the aforementioned advantages, the connection of PEV to the power grid poses a series of new challenges for electric utilities. This paper proposes a comprehensive approach for evaluating the impact of different levels of PEV penetration on distribution network investment and incremental energy losses. The proposed approach is based on the use of a large-scale distribution planning model which is used to analyze two real distribution areas. Obtained results show that depending on the charging strategies, investment costs can increase up to 15% of total actual distribution network investment costs, and energy losses can increase up to 40% in off-peak hours for a scenario with 60% of total vehicles being PEV.

Assessment of the Impact of Plug-in Electric Vehicles on Distribution Networks

Probabilistic electric load forecasting: A tutorial review

In this paper, the transmission planning state-of-the-art, which was obtained from the review of the most interesting models found in the international technical literature, is presented. The classification of publications was made, keeping in mind the solution methods, the treatment of the planning horizon, and the consideration of the new competitive schemes in the power sector. A discussion about the available tools for development of transmission planning models is also included.

Classification of publications and models on transmission expansion planning

Multiphase variable-speed drives and generation systems (systems with more than three phases) have become one of the mainstream research areas during the last decade. The main driving forces are the specific applications, predominantly related to the green agenda, such as electric and hybrid electric vehicles (EVs), locomotive traction, ship propulsion, “more-electric” aircraft, remote offshore wind farms for electric energy generation, and general high-power industrial applications. As a result, produced body of significant work is substantial, making it impossible to review all the major developments in a single paper. This paper therefore surveys the recent progress in two specific areas associated with multiphase systems, namely power electronic supply control and innovative ways of using the additional degrees of freedom in multiphase machines for various nontraditional purposes.

/pdf/advances-in-converter-control-and-innovative-exploitation-of-3nc3l7z4ta.pdf

Advances in Converter Control and Innovative Exploitation of Additional Degrees of Freedom for Multiphase Machines

This paper presents the evaluation of saturation and cross-magnetization effects in an interior permanent magnet synchronous motor (IPMSM) over the entire range of direct- and quadrature-axis excitations. The conventional two-axis machine model is modified in order to include the influence of saturation and cross-coupling effects on the variation of self- and cross-coupling inductances in the direct and the quadrature axis. The two-axis machine model parameters are evaluated by experiments performed on an IPMSM using a controlled voltage-source inverter and are compared with parameter values evaluated by the finite-element method. The evaluation of two-axis machine model parameters reveals significant saturation and cross-magnetization effects in both axes, especially in the flux-weakening regime.

Evaluation of saturation and cross-magnetization effects in interior permanent-magnet synchronous motor

Cross-saturation effect in synchronous machines has been a subject of considerable attention. Inclusion of the cross-saturation in the machine model has two consequences. The first one, called here "steady-state cross-saturation", consists of dependence of the steady-state d-q axis magnetizing inductances on the currents in both axes. The second one, termed here "dynamic cross-saturation", is the existence of nonzero elements in the system matrix, that describe cross coupling between d- and q-axis. Dynamic cross-saturation appears in all the saturated machine models, regardless of the selected set of state-space variables, with the exception of the winding flux linkage state-space model. The aim of this paper is to compare behavior of various models when dynamic cross-saturation is neglected. It is shown that the impact of dynamic cross-saturation on accuracy depends on the selected set of state-space variables. In the majority of cases omission of dynamic cross-saturation leads to very inaccurate results. However, it is found that for one particular class of models, omission of dynamic cross-saturation has practically no impact on accuracy. These models therefore fully describe the complete saturation effect by means of only continuous variation of the d-q axis magnetizing inductances.

Impact of dynamic cross-saturation on accuracy of saturated synchronous machine models

This paper considers two isolated solutions for fast charging of electric vehicles (EVs). The isolation is located on the grid side (off board), whereas the rest of the charging apparatus is placed on board the EV, and it entirely consists of the existing power electronics components that would be otherwise used only for propulsion. Thus, substantial savings on space, weight, and cost are achieved. The considered configurations fully incorporate either a symmetrical or an asymmetrical six-phase machine, as well as a six-phase inverter, into the charging process. Due to the nature of the connections, torque production is avoided during the charging/vehicle-to-grid (V2G) modes of operation. Thus, the machines do not have to be mechanically locked, and their rotors naturally stay at standstill. Control schemes for both configurations are elaborated, and theoretical results are validated by experiments for the two configurations in both charging and V2G modes.

/pdf/isolated-chargers-for-evs-incorporating-six-phase-machines-4v33oi1uc4.pdf

Isolated Chargers for EVs Incorporating Six-Phase Machines

A new method is presented for long-range transmission network expansion planning, based on the decomposition principle. The overall transmission expansion planning task is divided into two problems, the first one dealing with investments, and the second with operations. The investment problem is specified as the minimum cost problem of network programming, leading to the decomposition into the model of minimum load curtailment and the proposed model of the (local) marginal network. The operation problem is solved by applying the Monte Carlo simulation, with suitable control strategies and additional reliability constraints. The final result is the software package, verified on test examples, as well as on the real transmission network of the power pool of eastern Yugoslavia. >

A new decomposition based method for optimal expansion planning of large transmission networks

This paper proposes a probabilistic framework for optimal demand response scheduling in the day-ahead planning of transmission networks. Optimal load reduction plans are determined from network security requirements, physical characteristics of various customer types, and by recognizing two types of reductions, voluntary and involuntary. Ranking of both load reduction categories is based on their values and expected outage durations, while sizing takes into account the inherent probabilistic components. The optimal schedule of load recovery is then found by optimizing the customers’ position in the joint energy and reserve market, while considering several operational and demand response constraints. The developed methodology is incorporated in the sequential Monte Carlo simulation procedure and tested on several IEEE networks. Here, the overhead lines are modeled with the aid of either static-seasonal or real-time thermal ratings. Wind generating units are also connected to the network in order to model wind uncertainty. The results show that the proposed demand response scheduling improves both reliability and economic indices, particularly when emergency energy prices drive the load recovery.

/pdf/optimal-demand-response-scheduling-with-real-time-thermal-1f3wajwfdd.pdf

Optimal Demand Response Scheduling With Real-Time Thermal Ratings of Overhead Lines for Improved Network Reliability

The authors investigate emergency action in terms of secondary-voltage control and the system load shedding for prevention of voltage instability. Two modes of co-ordination of these control methods with corresponding models are proposed, and these are summarised into developed emergency-control algorithms. The emergency actions of the individual controls and of the proposed co-ordinated control modes are then simulated on a real multimachine power system. The results so obtaned show the superiority of the proposed co-ordinated controls over a single control action in preventing voltage instability and system breakdown.

Victor Levi

Papers

Impact of dynamic cross-saturation on accuracy of saturated synchronous machine models

Isolated Chargers for EVs Incorporating Six-Phase Machines

A new decomposition based method for optimal expansion planning of large transmission networks

Optimal Demand Response Scheduling With Real-Time Thermal Ratings of Overhead Lines for Improved Network Reliability

Co-ordination of emergency secondary-voltage control and load shedding to prevent voltage instability