IEEE Industry Applications Society

This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material.

This paper reports on the continuing efforts of an IAS Working Group to investigate industry concerns with excessive stator fault-point burning damage in conjunction with various industrial generator grounding and ground fault protection practices. Previous working group efforts were reported in a series of papers discussing typical voltage bus connected industrial generator applications. These papers proposed a new method of grounding, called hybrid grounding, that offered the ability to limit damage while still providing the required level of ground fault current under all operating conditions. This new Working Group paper reports on the detailed design requirements for hybrid grounding. The paper reports the results of switching transient studies that formed the bases for recommended overvoltage protection. It also provides guidance in selection of equipment and fault protection required for hybrid grounding. The experience gained with several hybrid grounding applications is also reported.

In general, power software lacks lockout/tagout (LOTO) procedures and transfer/switching procedures-both critical shortcomings. In 2008, this Working Group (WG) was created to develop methodology for software programs addressing operational procedures, switching procedures including LOTO, and transfer procedures. The “User Guideline Specification” provides this methodology. Software itself will be developed by software vendors. Related was a goal to present a clear, simple, mathematical, and graphical language to promote rigorous analysis and virtual verification of the applicable software; a unified suite for an operational, mathematical, and graphical language. Referenced papers provide a sound basis for work toward achieving this goal, a task which the WG commends to future authors and Working Groups. Although it is outside the defined scope, the WG notes that these basic concepts apply to other energy systems. The WG encourages interested parties to develop similar approaches for other energy systems.

Abstract The paper focuses on theoretical design considerations of hybrid compensation systems, which include tuned L‐C filters, thyristor‐controlled reactors (TCR) and thyristor‐switched capacitors (TSC). The approach derives from optimum compensation technique employing parallel configuration of reactors and capacitors, where purely capacitive compensation is substituted by L‐C branches. This solution, recommended for distorted systems, allows a decomposition of the load currents in terms which are not strongly dependent of the source impedance. The method is also applied to the design of multiple tuned L‐C filters, taking into account load current harmonics and the effect of the supply impedance.

The critical loads, such as hospitals, data centers, institutional services, require systems of continuous availability and their design criteria has to be aimed not only at installation but also at the operational management of the system (In-Op design). This paper highlights how the topology of the infrastructure of a medium/low voltage system must offer performances by design for the service continuity and, in particular, a fault tolerant behavior. This paper suggests special modules of system for the mission critical loads recommending at least a dual-hot supply. These modules aim to guarantee the triple integrity levels ILs against loss services transitory, of short and long time. They also offer integrity resilience IR with adequate capacity of restoring service at every distribution level against maintenance exigencies, faults and utility disservices. Therefore, local power production systems become crucial and not primary with a smoother management. Essential complement to the integrity levels and resiliencies is the management staff. It has to be qualified, trained to operate the safety and integrity procedures for effective use of all the performances of the power systems with a safe service continuity. The paper deals with a case study to analyze some details on performances by design for the service continuity.

Abstract An artificial neural network (ANN) is used to optimally control a hybrid power compensator (HPC) consisting of a static VAR compensator (SVC) and a dynamic compensator (DC) during the compensation of nonlinear loads. The HPC must be controlled to meet minimum requirements in terms of power factor and harmonic distortion, while at the same time minimising its total cost. The ability of the ANN to adapt its output when subjected to a dynamic power system environment to achieve the above, is evaluated. The power system dynamics in this paper constitute line impedance changes and changes in the load conditions of other consumers coupled to the same network. A state space model of the power distribution network together with the HPC forms the basis of evaluation of the mentioned controller. The results obtained reveal that the ANN can meaningfully adapt its output to optimise the HPC performance.

The IEC/EN standards introduce the global grounding system GGS that ensures no dangerous touch voltages to all the interconnected grounding systems and, in practice, creates an intrinsically safe grounding system ISGS when permits indefinitely touch voltages no higher than the conventional limit value. The interconnection of the grounding systems through the cable shields of the utilities distribution contributes to constitute a global grounding system so that the utilities have the responsibility in validating the existence of a GGS. A grounding system, out of a GGS, has to satisfy safety conditions in reference to parameters of the point of delivery communicated by utility. The grounding systems, in metropolitan and commercial areas, are usually interfering and common external conductive parts interconnect them in fact. In these areas, an intentional integration between adjacent grounding systems of users, satisfying equal protection requirements, assists resolutely to satisfy the safety conditions of an ISGS. The constitution of grounding microgrid systems GMSs contribute to recognize and perfect situations in fact and promote the common interest of safety, regardless of formal validation from the utilities.

Robotics history is still HIS story, but Women in Robotics is working hard to include HER story in the future of robotics.

This paper is focused on the technical, regulatory, and financial evaluation of the electricity transmission service that a company can provide to an electricity generation company for the electric transmission lines services for a period of 30 years. The analysis includes the regulatory context and the role that each regulatory institution plays when evaluating a project of this large scale. This paper also describes asset management practices for the transmission lines that need to be considered when contracting the electricity transmission service. This paper additionally entails the regulatory frame for a hydroelectric power plant in Peru and the economic, technical, and financial factors that the company needs to consider when they want to connect their plant to a substation in the National Interconnected Electrical System (SEIN).

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The publication offers a note of thanks and lists its reviewers.

Challenges for integration of renewable resources into electrical systems vary depending on the characteristics of that system. Critical characteristics can be: physical, such as geographic distances and temperature ranges; technical, such as load profile and grid strength; political, whether the system is operated by an integrated utility or decentralized. Alberta is a Canadian Province with a population of 4.6 million, and a population density below 7 people per km2. The electrical system is deregulated, with peak load of approximately 12GW and daily variation of about 1GW. The talk will introduce some of the challenges and solutions to enable integration of renewable resources in the Alberta Interconnected Electrical System.