1、APPLICATIONS OF GPS IN POWER ENGINEERING,What is GPS?,GPS or Global Positioning Systems is a highly sophisticated navigation system developed by the United States Department of Defense. This system utilizes satellite technology with receivers and high accuracy clocks to determine the position of an
2、object.,The Global Positioning System,A constellation of 24 high-altitude satellites,GPS is,A constellation of satellites, which orbit the earth twice a day, transmitting precise time and position (Latitude, Longitude and Altitude) Information. A complete system of 21 satellites and 3 spares.,GPS at
3、 Work,Navigation - Where do I want to go? Location - Where am I? 3. Tracking - Monitoring something as it moves 4. Mapping - Where is everything else? 5. Timing - When will it happen?,Why do we need GPS?,Safe Travel Traffic Control Resource Management Defense Mapping Utility Management Property Loca
4、tion Construction Layout,4 birds (as we say) for 3-D fix,Global Positioning Systems (GPS) Applicationsin Power Systems,Power companies and utilities have fundamental requirements for time and frequency to enable efficient power transmission and distribution. Repeated power blackouts have demonstrate
5、d to power companies the need for improved time synchronization throughout the power grid. Analyses of blackouts have led many companies to place GPS-based time synchronization devices in power plants and substations,Why GPS For power Eng,It furnishes a common-access timing pulsewhich is accurate to
6、 within 1 microsecond at anylocation on earth.A 1-microsecond error translates into 0.021for a 60 Hz system and 0.018 for a 50 Hz system and is certainly more accurate than any other application,GPS time synchronization,By synchronizing the sampling processes for different signals which may be hundr
7、eds of kilometers apart it is possible to put their phasors in the same phasor diagram,GPS time synchronization,Absolute Time Reference Across the Power System,Synchronized phasor measurements (SPM) have become a practical proposition. As such, their potential use in power system applications has no
8、t yet been fully realized by many of power system engineers.,Phasor Measurement Units PMUs,Phasor Measurement Units (PMU) or SYNCHROPHASORS,DAWN OF THE GRID SYNCHRONIZATION,Phasor Measurement Units )PMU),They are devices which use synchronization signals from the global positioning system (GPS) sate
9、llites and provide the phasor voltages and currents measured at a given substation.,Phasor Measurement Units PMUs,Secondary sides of the 3 P.T. or C.T.,Corresponding Voltage or Current phasors,input,output,PMU,Phasor Measurement Units PMUs,Phasor Monitoring Unit (PMU) Hardware Block Diagram:,Samplin
10、g at Fixed Time Intervals Using an Absolute Time Reference,The GPS receiver provides the 1 pulse-per-second (pps) signal, and a time tag, which consists of the year, day, hour, minute, and second. The time could be the local time, or the UTC (Universal Time Coordinated).The l-pps signal is usually d
11、ivided by a phase-locked oscillator into the required number of pulses per second for sampling of the analog signals. In most systems being used at present, this is 12 times per cycle of the fundamental frequency. The analog signals are derived from the voltage and current transformer secondarys.,Th
12、e Birth of the PMUs,Computer Relaying developments in 1960-70s.,ABB,Now,RES 521,SEL-421,ABB,Phasor Measurement Units,Phasor Measurement Units PMUs,Data Concentrator (Central Data Collection),ABB,Different applications of PMUs in power system,Adaptive relaying Instability prediction State estimation
13、Improved control Fault recording Disturbance recording Transmission and generation modeling verification Wide area Protection Fault location,Applications of PMU in power System,1-Adaptive relaying,Adaptive relaying is a protection philosophy which permits and seeks to make adjustments in various pro
14、tection functions in order to make them more tuned to prevailing power system conditions,Applications of PMU in power System,2-Instability prediction, The instability prediction can be used to adapt load shedding and/or out of step relays., We can actually monitor the progress of the transient in re
15、al time, thanks to the technique of synchronized phasor measurements.,Applications of PMU in power System, The state estimator uses various measurements received from different substations, and, through an iterative nonlinear estimation procedure, calculates the power system state.,3-State estimatio
16、n, By maintaining a continuous stream of phasor data from the substations to the control center, a state vector that can follow the system dynamics can be constructed., For the first time in history, synchronized phasor measurements have made possible the direct observation of system oscillations fo
17、llowing system disturbances,Applications of PMU in power System, Power system control elements use local feedback to achieve the control objective.,4-Improved control,The PMU was necessary to capture data during the staged testing and accurately display this data and provide comparisons to the syste
18、m model.,The shown figure shows a typical example of one of the output plots from the PMU data,Applications of PMU in power System, They can capture and display actual 60/50 Hz wave form and magnitude data on individual channels during power system fault conditions.,5-Fault Recording,Applications of
19、 PMU in power System, Loss of generation, loss of load, or loss of major transmission lines may lead to a power system disturbance, possibly affecting customers and power system operations.,6-Disturbance Recording,Applications of PMU in power System,These figures are examples of long-term data used
20、to analyze the effects of power system disturbances on critical transmission system buses.,Disturbance Recording,Applications of PMU in power System, Computerized power system modeling and studies are now the normal and accepted ways of ensuring that power system parameters have been reviewed before
21、 large capital expenditures on major system changes.,7-Transmission and Generation Modeling Verification, In years past, actual verification of computer models via field tests would have been either impractical or even impossible, The PMU class of monitoring equipment can now provide the field verif
22、ication required,Applications of PMU in power System, The shown figure compares a remote substation 500 kV bus voltage captured by the PMU to the stability program results,7-Transmission and Generation Modeling Verification,Applications of PMU in power System,The introduction of the Phasor Measureme
23、nt Unit (PMU) has greatly improved the observability of the power system dynamics. Based on PMUs, different kinds of wide area protection, emergency control and optimization systems can be designed,8-Wide Area protection,Applications of PMU in power System,A fault location algorithm based on synchro
24、nized sampling. A time domain model of a transmission line is used as a basis for the algorithm development. Samples of voltages and currents at the ends of a transmission line are taken simultaneously (synchronized) and used to calculate fault location.,9-Fault Location,Applications of PMU in power
25、 System,The Phasor measurement units are installed at both ends of the transmission line. The three phase voltages and three phase currents are measured by PMUs located at both ends of line simultaneously,Fault Location,Applications of PMU in power System,SPM-based applications in power systems,off-
26、line studiesreal-time monitoring and visualizationreal-time control, protection and emergency control,42,SOME RESEARCH PROGECTS (I participated in),Global Positioning System (GPS)-Based Synchronized Phasor Measurement,By Eng. Marwa M. Abo El-Nasr,Supervised by Prof. Dr. Mohamed M. Mansour Dr. Said F
27、ouad Mekhemer,CONCLUSIONS,The conclusions extracted form the present work can be summarized as follows:A technique for estimating the fault location based on synchronized data for an interconnected network is developed and implemented using a modal transformOne-bus deployment strategy is more useful
28、 than tree search for fault location detection as it gives more system observability,3- The average value of mode 1 and 2 of Karrenbauer transformation is used for 3-phase and line-to-line faults, while the average value of the 3 modes is used for line-to-line-ground and line-to-ground faults4- The
29、results obtained from applying the developed technique applied to a system depicted from the Egyptian network show acceptable accuracy in detecting the fault and locations of different faults types.,Conclusions,STATE ESTIMATION AND OBSERVABILITY OF LARGE POWER SYSTEM USING PHASOR MEASUREMENT UNITS,E
30、ssence:,This thesis is to address three issues: 1- Optimal allocation of Phasor Measurement Units (PMUs) using Discrete Particle Swarm Optimization (DPSO) technique. 2- Large scale power system state estimation utilizing the optimal allocation of PMUs based on Global Positioning Systems (GPS). 3- Po
31、wer system voltage stability monitoring based on the allocated PMUs readings.,49,Wide Area Protection System for Maximizing Power System Stability,Prepared By Fahd Mohamed Adly HashieshUnder Supervision of Prof. Dr. M. M. Mansour Dr. Hossam Eldin M. Atia Dr. Abdel-Rahman A. KhatibCairo Egypt 2006,Re
32、search Objective,Propose a protection system (strategy) to counteract wide area disturbance (instability), through employing adaptive protection relays, and fast broadband communication through wide area measurement.Configure and adapt the proposed system to be applied on Egypt wide power system net
33、work.,50,A Master Student is Trying to Implement a PMU Lab Prototype in Ain-Shams Univ.,CONCLUSIONS AND FUTURE WORKS,thanks to their multiple advantages, nowadays, the technologies based on synchronized phasor measurements have proliferated in many countries worldwide (USA, Canada, Europe, Brazil, C
34、hina, Egypt !,). up to now most applications based on synchronized phasor measurements have concerned mainly off-line studies, on-line monitoring and visualization, and to a less extent the real-time control, Protection, and the emergency control. the toughest challenge today is to pass from Wide Ar
35、ea Measurements Systems (WAMS) to Wide Area Control Systems (WACS) and WAP.,52,Thank You,Off-line SPM-based applications,software simulation validation SPM-based technologies can be very useful to help the validation of (dynamic) simulation software system parameter/model identification (e.g. for lo
36、ads, lines, generators, etc.) the identification of accurate model/parameter is a very important and tough task for the power system analysis and control. difficulty: large number of power system components having time-varying characteristics. synchronized disturbances record and replay this task is
37、 like that of a digital fault recorder, which can memorize triggered disturbances and replay the recorded data if required. the use of SPM allows more flexibility and effectiveness.,54,Real-time monitoring SPM-based applications,fault location monitoring accurate fault location allows the time reduc
38、tion of maintenance of the transmission lines under fault and help evaluating protection performance. power system frequency and its rate of change monitoring the accurate dynamic wide-area measured frequency is highly desirable especially in the context of disturbances, which may lead to significan
39、t frequency variation in time and space. generators operation status monitoring this function allows the drawing of generator (P-Q) capability curve. Thus, the generator MVAr reserve, can be supervised. transmission line temperature monitoring the thermal limit of a line is generally set in very con
40、servative criteria, which ignores the actual cooling possibilities. The use of SPM allows the higher loading of a line at very low risk. on-line “hybrid“ state estimation the SPM can be considered, in addition to those from the Remote Terminal Units (RTU) of the traditional SCADA system, in an on-li
41、ne “hybrid“ state estimation. SPM-based visualization tools used in control centers display: dynamic power flow, dynamic phase angle separation, dynamic voltage magnitude evolution, real-time frequency and its rate of change, etc.,55,Real-time (emergency) control SPM-based applications,automatic (se
42、condary and tertiary) voltage control aim: optimize the var distribution among generators, controllable ratio transformers and shunt elements while keeping all bus voltage within limits. in the context of WAMS application, the solution of this optimization problem can be used to update settings of t
43、hose reactive power controllers, every few seconds. damping of low frequency inter-area oscillations (small-signal angle instability) low frequency inter-area oscillations (in the range of 0.2 1 Hz) are a serious concern in power systems with increasing their size and loadability. In Europe, in part
44、icular, many research studies have been performed to reveal such oscillations as well as provide best remedial actions to damp them out. transient angle instability since such instability form develops very quickly, nowadays, Special Protection Systems (SPS), also known as Remedial Action Schemes (R
45、AS), are designed to act against predefined contingencies identified in off-line studies while being less effective against unforeseen disturbances.,56,Real-time (emergency) control SPM-based applications (contd),short- or long-term voltage instability a responde-based (feedback) Wide-Area stability
46、 and voltage Control System (WACS) is presently in use by BPA. this control system uses powerful discontinuous actions (switching on/off of shunt elements) for power system stabilization.frequency instability the underfrequency load shedding has its thresholds set for worst events and may lead to ex
47、cessive load shedding. new predictive SPM-based approaches are proposed aiming to avoid the drawbacks of the conventional protection.,57,Conclusions:,A new modified DPSO technique is developed to determine the optimal number and locations for PMUs in power system network for different depths of unob
48、servability. It gives the optimal PMUs allocation for different depths of unobservability comparable to other techniquesThe developed DPSO is tested on both 14-bus and 57-bus IEEE standard systems. For small power systems, DPSO gives either equivalent or better results. However for large power syste
49、ms, it gives almost better locations and sometimes less number of PMUs for large power systems. DPSO determines the optimal PMUs allocation for complete observability of the large system depicted from the Egyptian unified electrical power network.,A- Discrete Particle Swarm Optimization Technique:,C
50、onclusions (continued):,The phasors readings of PMUs are taken into consideration in a new hybrid state estimation analysis to achieve a higher degree of accuracy of the solution. The effect of changing the locations and numbers of PMUs through the buses of the power network on the system state esti
51、mation is also studied with a new methodology. The hybrid state estimation technique is tested on both 14-bus and 57-bus IEEE standard systems. It is also applied to a large system depicted from the Egyptian unified electrical power network.PMUs outputs affect the state estimation analysis in a precious way. It improves the response and the output of the traditional state estimation.,
