Advanced Materials Research Vols. 614-615

Abstract: To overcome the problem that the artificial scheduling can not deal with optical fiber switching in time when optical fiber is broken or damage in power system, we designed an optical fiber line auto switch protection system. The system used six 4x4 optical switches to compose an optical switch array that eight working fibers can share four alternate fibers. Comparing with other system, the new system more effectively utilizes alternate fibers, and is more suitable for practical power system. It used single chip microcomputer as control chip of optical switch, when the received optical power is lower than predefined threshold, the control chip will control the optical switch to alternate fiber line in time to ensure the real time and reliability of optical fiber communication. In the same time, the new system can communicate with host computer to alarm, display fault optical fiber line and remote control, and be controlled by button to realize the manual switch of optical fiber line.

Abstract: Harmonic detection is one of the most important core part of Active Power Filter,which can quickly and accurately detect the harmonic current that is the premise of circuit to quickly output harmonic compensation current,therefore the pros and cons of the detection method,a direct impact on the effect of harmonic compensation.Time compensation method is to add a specific time compensation angle based on the method of instantaneous reactive power compensation,so that it can accurately detect the harmonic currents at the same time,minimize the low-pass filter time delay.By MATLAB simulation,the results show high detection accuracy.And to ensure detection and compensation,while fully to improve the real-time function of the filter.

Abstract: This paper presents a uniform algorithm for single-phase and three-phase load flow calculation. Firstly, two iterative equations with static factors are studied for single-phase power flow calculation based on Gauss power flow algorithm. One is used for all PQ nodes iteration similar to the traditional Gauss power flow algorithm, and the other one is exploited for all PV nodes and the slack node, which is a new algorithm studied in this paper. Then, the three-phase power flow iterative equations are studied. Virtual generator nodes are generated so that it is enough to built equations to solve the unknown parameters and each equation has a unique solution. Two iterative equations are studied for three-phase power flow calculation based on the single-phase formulation studied in this paper. The calculation result shows that the algorithm has the advantage of fast calculation speed, reliable convergence and powerful applicability. It has been shown that the algorithm is suitable for online calculation of single-phase and three-phase power system.

Abstract: This paper analyzes protective data flow in normal state and after failure with IEC 61850 D2-2 type substation. Focusing on the flow which conform to IEC 61850 Ethernet protocol by using Optimized Network Engineer Tools (OPNET) simulator, the protective data in D2-2 type substation is simulated based on IEEE 802.1Q priority-tag and VLAN technology. A sample Substation Automatic System (SAS) network is constructed, and the main factors affecting the delay of protective data is discussed in detail.

Abstract: In a centralized control center SCADA system, thousands of real-time data are sent to SCADA, including real-time signal, telemetering and alarm information. The intelligent analysis and processing of alarm signals is an important requirement. This article from the design point of intelligent alarm rules, explore an internal reasoning knowledge base and the external definition of rules combined design algorithm. Practical application results show that, the algorithm to power a variety of abnormal and fault has better capture and analysis ability.

Abstract: Distribution system reconfiguration is the main measure to optimize the distribution system, which can dramatically lower the power loss of the network. This paper deals with the switch operation sequence considering closed-loop current constraints and puts forward the concept of “switch compounding”. A new implementation strategy is proposed to realize a feasible operation sequence. The strategy is tested on IEEE33 system, which verifies the effectiveness of the strategy.

Abstract: Conducting regular inspections and measurements of power lines is an important way to ensure the stability and security of transmission line. For the problem of being poor reliability, poor flexibility and high cost, a power line measurement method based on vertical baseline photography is proposed and studied: Line patrol officers use portable vertical baseline stereo camera shooting in the outdoor field, and measure accurately in the stereo image taken in or after patrol. This paper describes the system design and technical methods, and analyzes the key technologies in the system calibration and measurement, and uses several sets of experiments to prove the accuracy and feasibility of this method.

Abstract: To study the DC transmission system, and control it in real-time, many researchers make models based on the Fourier decomposition method. However, their calculations are not very precise. In this paper, a new mathematical model for the DC transmission system was build, by use of the Fourier formulas to decompose the current on the converter transformer’s valve side. Formulas for the operating parameters of both rectifier station and inverter station were derived, and the effects of the harmonics were considered. Results from theoretical calculations and experimental collection show that waveforms of the operating parameters are very similar. Even the experimental waveforms change a little, the calculation results can reflect the change clearly, which fully prove that the theoretical analysis is correct and the mathematical model is accurate.

Abstract: The characteristics of wind power such as wave properties, intermittence, seasonal nature, counter regulation and so on have negative effect on power grid; grid-connected wind power on a scale is limited. To aim at the problem that there lacks quantification evaluation method on grid-connected wind power, an comprehensive evaluation index system concerning safety, adequacy, power quality and economy on the power grid which wind power is accepted. By using current advanced fuzzy interval analytic hierarchy process (FIAHP) , analyzing index such as static stability reserve coefficient, peak margin and transmission reliability margin and so on, coming up with the potential risk, thus on the condition of system safety and steady operation, penetrating power can be maximization, utilization rate improved. At last, analysis of the example proves that the evaluation index system and evaluation method is scientific and feasible.

Abstract: With the build of Monitoring Center in our country, a great of signals are uploaded from many substations which are located on every corner. When an abnormal or a grid fault in Power System happens, lots of signals come out, then many operators on duty can’t often react quickly and judge the fault accurately.Recently，more and more scholars begin studying intelligent alarm processing system. In this paper, by analyzing signals characters and SCADA network of Monitoring Center, an intelligent processing frame to alarms in monitoring center is provided, the frame includes three layers named signals foundation treatment layer, signals connecting and sharing layer, signals intelligent diagnosis layer. Now the frame has been implemented successfully in Monitoring Center of our company. At the same time, based on an virtual signals software, lots of devices alarms and grid faults are simulated, this intelligent processing system, which are built on the frame, always show the alarm tip quickly. Facts prove it attributes to grid fault judge for operators of Monitoring Center.