Among different sources of alternate energy, wind and solar are two prominent and promising alternatives to meet the future electricity needs for mankind. Generally, these sources are integrated at the distribution utilities to supply the local distribution customers. If the power generated by these sources is bulk, then they are either integrated at the distribution/transmission level or may be operated in an island mode if feasible. The integration of these renewables in the power network will change the fault level and network topologies. These fault levels are intermittent in nature and existing protection schemes may fail to operate because of their pre-set condition. Therefore, the design and selection of a proper protection scheme is very much essential for reliable control and operation of renewable integrated power systems. Depending upon the level of infeed and location of the renewable integration, the protection requirements are different. For low renewable infeed at the distribution level, the existing relay settings are immune from any small change in the network fault current from new incoming renewables. However, bulk renewable infeed requires modification in the existing protection schemes to accommodate the fault current variation from the incoming renewables. For bulk penetration of the renewable, the requirement of modified/additional protection schemes is unavoidable. Adaptive relaying and non-adaptive relaying schemes are discussed in the literature for protection of power networks, which are experiencing dynamic fault currents and frequent changing network topologies. This article presents a detailed review of protection schemes for renewable integrated power networks which includes distribution, transmission and microgrid systems. The merits and demerits of these protection schemes are also identified in this article for the added interest of the readers. The visible scope of advance protection schemes which may be suitable for providing reliable protection for dynamic fault current networks is also explored.

Protection challenges under bulk penetration of renewable energy resources in power systems: A review

This presentation introduces Smart Grid and associated technical, environmental and socio-economic, and other non-tangible benefits to society, and articulates the need for the concept and the fact that it is a dynamic interactive, real-time infrastructure that responds to the challenges of designing and building the power system of the future, rather than being simply a marketing term. To illustrate the diversity of terminology, we compare an Electric Power Research Institute (EPRI) definition with that suggested by a study group of the International Electrotechnical Commission (IEC). Next, a paper sponsored by the Canadian Electricity Association (CEA) that cites three example definitions to highlight the diversity of views of Smart Grid is briefly reviewed. Early misconceptions and characterizations of Smart Grid are discussed as a prelude to addressing challenging issues that motivate developing and implementing related innovative technologies, products and services. We then discuss the potential promise of the Smart Grid, which is embedded in its often-cited attributes of efficiency, accommodating, quality focus, enabling and self-healing to name some. The presentation then addresses some of the often-cited impediments to accepting Smart Grid which are based on concerns and issues confronting its forward progress, adoption and acceptance. Distribution Automation (DA) and embedded intelligence are discussed emphasizing self-healing, optimizing operation and facilitating recreation and recovery from abnormal events. Functional and integration requirements of Distributed Energy Resources (DER,) are detailed. Smart Consumption Infrastructure elements of Distribution Management Systems (DMS,) Automated Metering Infrastructure (AMI,) Smart Homes (SH), and Smart Appliances (SA,) are discussed. We discuss smart grid activities in China, India, and the development of a Smart Grid roadmap for the US State of Kentucky. The approaches of each of these cases reflect the diversity of policy initiatives in these jurisdictions. State of the art reviews of distribution network active management and future development trends in technologies and methods, where centralized and decentralized management frameworks and applying agent-based coordination are discussed. A review of smart home technologies and the goals of an energy management system (SHEMS) are also discussed.

The Smart Grid—State-of-the-art and future trends

The strengthening of electric energy security and the reduction of greenhouse gas emissions have gained enormous momentum in previous decades. The integration of large-scale intermittent renewable energy resources (RER) like wind energy into the existing electricity grids has increased significantly in the last decade. However, this integration poses many operational and control challenges that hamper the reliable and stable operation of the grids. This article aims to review the reported challenges caused by the integration of wind energy and the proposed solutions methodologies. Among the various challenges, the generation uncertainty, power quality issues, angular and voltage stability, reactive power support, and fault ride-through capability are reviewed and discussed. Besides, socioeconomic, environmental, and electricity market challenges due to the grid integration of wind power are also investigated. Many of the solutions used and proposed to mitigate the impact of these challenges, such as energy storage systems, wind energy policy, and grid codes, are also reviewed and discussed. This paper will assist the enthusiastic readers in seeing the full picture of wind energy integration challenges. It also puts in the hands of policymakers all aspects of the challenges so that they can adopt sustainable policies that support and overcome the difficulties facing the integration of wind energy into electricity grids.

/pdf/grid-integration-challenges-of-wind-energy-a-review-1vqvbi73fa.pdf

Grid Integration Challenges of Wind Energy: A Review

In a traditional power grid, power generation is done at various potential locations and transmitted into power grid and then distributed to the customer premises The traditional grid incurs heavy investment, limited reliability, increased emissions of green house gases and increased transmission line losses It has made the utility to opt for connecting numerous renewable based micro sources near the customer premises, as per their requirement and providing intelligent control for the grid As a comprehensive solution, microgrids are suggested by the researchers which would provide reliable, quality and efficient supply to its customers The connection of microgrid in the existing distribution network makes the radial network more complicated It also causes the magnitude of fault current to change dynamically depending on the modes of operation (grid connected or islanded mode), type of distributed generator, status of distributed generators and number of distributed generators The conventional protection schemes are designed for radial power flow with centralized power generation, which makes the existing protection scheme to fail with the microgrid Hence, an attempt is made to relook into the basic concepts and significance of microgrid, issues faced by the microgrid in the context of protection and various protection strategies

A review on issues and approaches for microgrid protection

This paper aims to highlight the advancement on the emergent technologies, implementations, and applications in smart power grid and city. Advanced sensing systems and smart transducers are used to improve the performances of electric grid and city services. The final aim is to provide readers with a clearer understanding of the current state of the art about this topic by describing some applications and suggesting new features and ideas in the field of sensors and sensing systems dedicated to smart electric grid, power networks, and smart cities.

Advances on Sensing Technologies for Smart Cities and Power Grids: A Review

This paper presents a new wide-area backup protection scheme based on the phase angle of positive-sequence integrated impedance (PAPSII). The proposed scheme uses phasor measurement units (PMUs) that comply with standard C37.118.1-2011 for retrieving the phasor information. The PMUs provide the positive-sequence phasor information of the voltage and current signals at each and every bus of a system to a phasor data concentrator (PDC). The positive-sequence integrated impedance of each line of the system is extracted, and the PAPSII of each line is continuously monitored at the PDC. The values of the PAPSII help in identifying the faulted line of the power transmission system. The proposed scheme is extensively tested for different types of fault scenarios on a three-machine nine-bus power transmission network on a real-time digital simulator platform. Critical issues such as voltage inversion, current inversion, load encroachment, and the power swing are addressed in the proposed scheme. The test results indicate that the proposed scheme can overcome the limitations of existing backup protection schemes and can provide a reliable protection measure.

A New Wide-Area Backup Protection Scheme for Series-Compensated Transmission System

Adaptive distance relay setting for parallel transmission network connecting wind farms and UPFC

Fault during a power swing is a challenging task for the distance relay functioning This article presents a spectral energy function for fault detection during a power swing using a novel time frequency transform known as the S-transform, a variable windowed short-time Fourier transform, which combines the elements of short-time Fourier transform and wavelet transform Initially, the current signal is preprocessed using S-transform to generate the S-matrix and corresponding S-contours (time–frequency contours) The spectral energy content of the S-counters is used to register symmetrical and unsymmetrical faults during a power swing and, based on a set threshold on the spectral energy, the relay blocks during a power swing and issue of the tripping signal during fault The proposed technique is tested for different fault conditions during a power swing with possible variations in operating parameters, including the ability to identify the faults with a response time of 125 cycles from the fault

A Novel Time–Frequency Transform Based Spectral Energy Function for Fault Detection During Power Swing

Differential relaying scheme for tapped transmission line connecting UPFC and wind farm

The paper presents a high impedance fault (HIF) detection scheme for microgrid using maximal overlapping discrete wavelet transform (MODWT) and decision tree (DT). The small, nonlinear, random and widely varying fault current of HIF makes the over-current relay insensitive. Thus, time-frequency information is required to distinguish HIF from no-fault event. The proposed work start with retrieving the fault current which is pre-process through (decompose using) MODWT to get the details and approximation coefficient. Further, some statistical features are estimated using the details and approximation coefficient. The features extracted are used to train decision tree (DT) for accurate classification of HIF from no-fault. The proposed scheme is tested for HIFs detection in microgrid for different operating conditions. The test results show that the proposed scheme provides an effective protection measure against HIFs for safe and secured operation of microgrid.

S. R. Samantaray

Papers

A New Wide-Area Backup Protection Scheme for Series-Compensated Transmission System

Adaptive distance relay setting for parallel transmission network connecting wind farms and UPFC

A Novel Time–Frequency Transform Based Spectral Energy Function for Fault Detection During Power Swing

Differential relaying scheme for tapped transmission line connecting UPFC and wind farm

High impedance fault detection in microgrid using maximal overlapping discrete wavelet transform and decision tree