Improving the performance of power system protection using wide area monitoring systems

Wide area monitoring(WAM) offers many opportunities to improve the performance of power system protection. This paper presents some of these opportunities and the motivation for their development. This methods include monitoring the suitability of relay characteristics,supervisory control of backup protection, more adaptive and intelligent system protection and the creation of novel system integrity protection scheme. The speed of response required for primary protection means that the role WAM in enhancing protection is limited to backup and system protection. The opportunities offered by WAM for enhancing protection are attractive because of the emerging challenges faced by the modern power system protection. The increasingly variable operating conditions of power systems are making it ever more difficult to select relay characteristics that will be a suitable compromise for all loading conditions and contingencies. The maloperation of relays has contributed to the inception and evolution of 70 % of blackouts,thus the supervision of the backup protection may prove a valuable tool for preventing or limiting the scale of blackouts. The increasing interconnection and complexity of modern power systems has made them more vulnerable to wide area disturbances and this has contributed to several recent blackouts. The proper management of these wide area disturbances is beyond the scope of most of the existing protection and new, adaptive system integrity protection schemes are needed to protect power system security.

Deployment and demonstration of wide area monitoring system in power system of Great Britain

The creation of a suitable wide area monitoring system(WAMS) is widely recognized as an essential aspect of delivering a power system that will be secure,efficient and sustainable for the foreseeable future. In Great Britain(GB), the deployment of the first WAMS to monitor the entire power system in real time was the responsibility of the visualization of real time system dynamics using enhanced monitoring(VISOR) project. The core scope of the VISOR project is to deploy this WAMS and demonstrate how WAMS applications can in the near term provide system operators and planners with clear, actionable information. This paper presents the wider scope of the VISOR project and the GB wide WAMS that has been deployed. Furthermore, the paper describes some of the WAMS applications that have been deployed and provides examples of the measurement device performance issues that have been encountered during the project.

Co-seismic changes of well water level and volume strain meter in capital area and its vicinity,due to the Nov.14,2001 Ms8.1 Kunlun Mountain earthquake,China

The Kunlunshan Mountain Ms8.1 earthquake, occurred in Nov.14, 2001, is the first event with magnitude more than 8 in the China earthquake monitoring history, specifically at the beginning of digital techniques in precursor monitoring networks. Any investigation of recorded data on this earthquake is very important for testing the operation of the digital monitoring networks and understanding the preparation, occurrence, and adjustment of stress/strain of strong continental earthquakes. In this paper we investigated the coseismic response changes of well water level of groundwater and volume strain meter of bore hole in digital earthquake monitoring network of Capital area and its vicinity, due to the Nov.14, 2001 Ms8.1 Kunlun Mountain earthquake. The responding time, shapes or manners, amplitudes, and lasting time of well water level and strain-meters to seismic wave are studied in comparison. Then we discussed the possibility that the response changes of groundwater to strong distant earthquakes can be understood as one kind of observing evidence of stress/strain changes induced by distant earthquake.

Guest editorial: special issue on wide area monitoring, protection and control in smart grid

Complexity of modern electrical power systems is steadily increasing.This is inspiring researchers and developers to propose new solutions capable to address a number of challenges,particularly those related to power system operation.A massive penetration of asynchronously connected renewable energy generation,the generation connected over inverters,is significantly changing the dynamics of modern power systems.From one hand,the power system response time is becoming shorter and at the same time the fault level is becoming smaller.This is significantly affecting requirements of control loops,as well as power system protection.

A novel method for locating the source of sustained oscillation in power system using synchrophasors data

Large interconnected power systems are usually subjected to natural oscillation(NO)and forced oscillation(FO).NO occurs due to system transient response and is characterized by several oscillation modes,while FO occurs due to external perturbations driving generation sources.Compared to NO,FO is considered a more severe threat to the safe and reliable operation of power systems.Therefore,it is important to locate the source of FO so corrective actions can be taken to ensure stable power system operation.In this paper,a novel approach based on two-step signal processing is proposed to characterize FO in terms of its frequency components,duration,nature,and the location of the source.Data recorded by the Phasor Measurement Units(PMUs)in a Wide Area Monitoring System(WAMS)is utilized for analysis.As PMU data usually contains white noise and appears as multi-frequency oscillatory signal,the first step is to de-noise the raw PMU data by decomposing it into a series of intrinsic mode functions(IMF)using Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(ICEEMDAN)technique.The most appropriate IMF containing the vital information is selected using the correlation technique.The second step involves various signal processing and statistical analysis tools such as segmented Power Spectrum Density(PSD),excess kurtosis,cross PSD etc.to achieve the desired objectives.The analysis performed on the simulated two-area four-machine system,reduced WECC-179 bus 29 machine system,and the real-time power system PMU data set from ISO New England,demonstrates the accuracy of the proposed method.The proposed approach is independent of complex network topologies and their characteristics,and is also robust against measurement noise usually contained in PMU data.

Adaptive relay co-ordination using a busbar splitting approach for a system integrity protection scheme

Power system faults can often result in excessively high currents.If sustained for a long time,such high currents can damage system equipment.Thus,it is desirable to operate the relays in the minimum possible time.In this paper,a busbar splitting approach is used for adaptive relay setting and co-ordination purposes for a system integrity protec-tion scheme(SIPS).Whenever a fault occurs,the busbar splitting scheme splits a bus to convert a loop into a radial structure.The splitting schemes are chosen such that the net fault current is also reduced.Busbar splitting elimi-nates the dependency upon minimum breakpoints set(MBPS)and reduces the relay operating time,thus making it adaptive.The proposed methodology is incorporated into the IEEE 14-bus and IEEE 30-bus systems with single and multiple fault conditions.The modeling and simulation carried out in ETAP,and the results of the proposed busbar splitting-based relay co-ordination are compared with the MBPS splitting-based relay co-ordination.

A database of global wetland validation samples for wetland mapping

A database of global wetland validation samples （GWVS） is the foundation for wetland mapping on a global scale. In this work, a database of GWVS was created based on 25 “wetland-related” keyw ord searches of a total of 3,506 full-text documents downloaded from the Web of Science. Eight hundred and three samples from a total of 68 countries and 14i protected areas were recorded by the GWVS, including samples of marine/coastal wetlands, inland wet- lands and human-made wetlands, at ratios of 53 %, 41% and 6 %, respectively. The results exhibit spatial distribution among Terrestrial Ecoregions of the World, the World Database on Protected Areas and the Database of Global Administrative Areas. Within most of the biomes, protected areas and countries examined, the very low concentration of samples requires more attention in the future. The greatest concentration of samples within a single biome is found in the tropical and subtropical moist broadleaf forest biome, accounting for 27 % of the total samples, while no sample is found in the biome of tropical and subtropical coniferous woodland. Greater efforts are expected to be made to record samples in Oceania, Central Europe, Northern Europe, Northern Africa, Central Africa, Central America, the Caribbean, and midwestern South America. Our data show that it is feasible to map global wetlands using Landsat TM/ ETM＋ at 30-m resolution. The continued improvement of the GWVS sharing platform should be reinforced in the future, making a strong contribution to global wetland mapping and monitoring.

Novel quantum-inspired firefly algorithm for optimal power quality monitor placement

The application of a quantum-inspired firefly algorithm was introduced to obtain optimal power quality monitor placement in a power system. The conventional binary firefly algorithm was modified by using quantum principles to attain a faster convergence rate that can improve system performance and to avoid premature convergence. In the optimization process, a multi-objective function was used with the system observability constraint, which is determined via the topological monitor reach area concept. The multi-objective function comprises three functions： number of required monitors, monitor over-lapping index, and sag severity index. The effectiveness of the proposed method was verified by applying the algorithm to an IEEE 118-bus transmission system and by comparing the algorithm with others of its kind.