Tarlochan S. Sidhu

A Control Strategy for Enhanced Operation of Inverter-Based Microgrids Under Transient Disturbances and Network Faults

This paper proposes an enhanced control strategy for electronically coupled distributed energy resources that improves the performance of the host microgrid under network faults and transient disturbances. The proposed control strategy does not require controller mode switchings and enables the electronically coupled distributed energy resources to ride through network faults, irrespective of whether they take place within the host microgrid or impact the upstream grid. Moreover, the proposed control ensures acceptable power quality for the duration of the faults, which is an important feature for protection against certain classes of faults, as well as for sensitive loads. Further, the paper proposes a supplementary control loop that improves the microgrid post-fault recovery. The effectiveness of the proposed control strategy is demonstrated through a comprehensive set of simulation studies, conducted in the PSCAD/EMTDC software environment.

A Communication-Assisted Protection Strategy for Inverter-Based Medium-Voltage Microgrids

This paper proposes a communication-assisted protection strategy implementable by commercially available microprocessor-based relays for the protection of medium-voltage microgrids. Even though the developed protection strategy benefits from communications, it offers a backup protection strategy to manage communication network failures. The paper also introduces the structure of a relay that enables the proposed protection strategy. Comprehensive simulation studies are carried out to verify the effectiveness of the proposed protection strategy under different fault scenarios, in the PSCAD/EMTDC software environment.

A Comprehensive Investigation of Wireless LAN for IEC 61850–Based Smart Distribution Substation Applications

Todays power grid is facing many challenges due to increasing load growth, aging of existing power infrastructures, high penetration of renewable, and lack of fast monitoring and control. Utilizing recent developments in Information and Communication Technologies (ICT) at the power-distribution level, various smart-grid applications can be realized to achieve reliable, efficient, and green power. Interoperable exchange of information is already standardized in the globally accepted smart-grid standard, IEC 61850, over the local area networks (LANs). Due to low installation cost, sufficient data rates, and ease of deployment, the industrial wireless LAN technologies are gaining interest among power utilities, especially for less critical smart distribution network applications. Extensive work is carried out to examine the wireless LAN (WLAN) technology within a power distribution substation. The first phase of the work is initiated with the radio noise interference measurements at 27.6- and 13.8-kV distribution substations, including circuit breaker switching operations. For a detailed investigation, the hardware prototypes of WLAN-enabled IEC 61850 devices are developed using industrial embedded systems, and the performance of smart distribution substation monitoring, control, and protection applications is analyzed for various scenarios using a round trip-time of IEC 61850 application messages. Finally, to examine the real-world field performance, the developed prototype devices are installed in the switchyard and control room of 27.6 power distribution substation, and testing results of various applications are discussed.

Investigations Into the Control and Protection of an Existing Distribution Network to Operate as a Microgrid: A Case Study

With the increasing attention to the concept of microgrids, it has become important to identify the requirements that enable an electric distribution network to operate as a microgrid. This paper studies a realistic distribution network to accomplish the following: 1) determine the conditions under which the network can operate as a microgrid and 2) present the control scenarios that allow the islanded operation of the network. In particular, the employment of electronically coupled distributed energy resources with the fault-ride-through and synchronization capabilities is investigated. Another objective of this paper is to propose practical protection strategies that are effective in both operational modes of a microgrid (i.e., the grid-connected mode and the islanded mode), considering the system constraints; the protection strategies provide the microgrid with acceptable reliability against different fault scenarios. The effectiveness of the control and protection strategies is demonstrated and discussed through a comprehensive set of simulation studies conducted in the PSCAD/EMTDC software environment.

Application of Compressive Sampling in Synchrophasor Data Communication in WAMS

In this paper, areas of power system synchrophasor data communication which can be improved by compressive sampling (CS) theory are identified. CS reduces the network bandwidth requirements of Wide Area Measurement Systems (WAMS). It is shown that CS can reconstruct synchrophasors at higher rates while satisfying the accuracy requirements of IEEE standard C37.118.1-2011. Different steady state and dynamic power system scenarios are considered here using mathematical models of C37.118.1-2011. Synchrophasors of lower reporting rates are exempted from satisfying the accuracy requirements of C37.118.1-2011 during system dynamics. In this work, synchrophasors are accurately reconstructed from above and below Nyquist rates. Missing data often pose challenges to the WAMS applications. It is shown that missing and bad data can be reconstructed satisfactorily using CS. Performance of CS is found to be better than the existing interpolation techniques for WAMS communication.

Design and Implementation of Multiagent-Based Distributed Restoration System in DAS

A distribution automation system (DAS) is a power automation system to operate a power distribution network efficiently through remote control and monitoring. The most important function of the DAS is the restoration of a stable power supply to the customer when a fault occurs. Since the DAS has a centralized structure, the restoration time of the DAS takes place in about 5 min. This is too long for a customer in the digital age, so a distributed restoration system, which can shorten the restoration time from 5 min to less than 1 min is proposed in this paper. The concept of a multiagent system (MAS) for a distributed control system is applied to the proposed system to enhance its operational reliability, but there is a belief that the MAS-based distributed operations system is just a future technology. So an application method is proposed in this paper for an MAS-based distributed restoration system without significant changes to the existing DAS. The proposed system was applied to an existing DAS and tested in the Gochang Power Testing Center. The test results showed that in the most complex case, the DAS restoration time was 48 s using a code-division multiple-access module and 10 s using an Ethernet communication module.

A Simple Synchrophasor Estimation Algorithm Considering IEEE Standard C37.118.1-2011 and Protection Requirements

In this paper, a simple synchrophasor estimation algorithm has been proposed considering power system steady state, dynamic conditions, and protection requirements. The new IEEE Standard C37.118.1-2011 for synchrophasor measurements includes the dynamic performance requirements for the phasor measurement units. It is shown that the proposed method satisfies all the steady state and dynamic requirements of the new IEEE Standard. Presently, synchrophasors are mainly used for wide area monitoring. Increasingly, synchrophasors are being considered for protection applications in smart grids. Protection applications require shorter response times and lower overshoot/undershoot values for estimated phasors during large disturbances. It is shown that the proposed method performs satisfactorily during system faults, which is an important requirement for protection applications. A detailed performance comparison with the existing phasor estimation algorithms has also been presented.

A High-Speed Adaptive Single-Phase Reclosing Technique Based on Local Voltage Phasors

In this paper, a new adaptive single-phase reclosing method for high-voltage transmission lines is proposed. This method employs local voltage magnitude and angle of the faulted phase. It is shown in this paper that the proposed method is able to quickly identify the fault type and the arc extinction if the fault is transient. This method is effective for various system configurations, including ideally and partially transposed transmission lines, untransposed lines, as well as transmission lines with or without a shunt reactor. Superior performance of the proposed method has been verified using 550 case studies simulated in PSCAD and Matlab and a real case related to a 765-kV transmission line.

Impact of Wind-Based Distributed Generation on Electric Energy in Distribution Systems Embedded With Electric Vehicles

In this paper, the synergy between wind-based distributed generation (DG) and plug-in electric vehicles (PEVs) is studied. MonteCarlo is used to address the uncertainties associated with wind speed variations and charging of PEVs hence simulating their impact at the distribution system (DS) level considering different DG penetration (up to 35%) and different PEV penetration (up to 50%). The excess in active/reactive power, energy exceeding normal (EEN), unserved energy (UE), and energy losses are investigated in this study. Forty-eight penetration scenarios involving DGs and PEVs are studied in this work and simulated in the IEEE 123-bus radial power distribution test system after modeling its secondary circuit in OpenDSS. The results of the simulation show that 30% wind-based DG penetration may be adequate to supply the active energy needed to charge PEVs. However, this might result in a reverse reactive power flow back to the substation.

An Optimal Composition and Placement of Automatic Switches in DAS

This paper proposes an algorithm for determining the optimal composition which means number of links and section switches in a feeder and placement of automatic switches in a distribution automation system (DAS). A DAS is configured by automatic switches and reclosers on a power distribution line. The composition and placement of switches affect the operational applications of a DAS. More switches lead to better DAS operation but also to increased cost and maintenance. Thus, this paper proposes an approach to determining the optimal composition and placement of automatic switches. Additionally, the proposed algorithm is developed considering various system topologies in a real field. The algorithm was tested on an example power distribution system with eight-feeders and on a real power distribution system operated by KEPCO in Young-Deung-Po and Jeju, South Korea.