太陽光発電が導入された配電系統における蓄電池の最適計画・制御手法に関する研究

早大学位記番号:新8188早稲田大

Push recovery with stepping strategy based on time-projection control

In this paper, we present a simple control framework for on-line push recovery with dynamic stepping properties. Due to relatively heavy legs in our robot, we need to take swing dynamics into account and thus use a linear model called 3LP which is composed of three pendulums to simulate swing and torso dynamics. Based on 3LP equations, we formulate discrete LQR controllers and use a particular time-projection method to adjust the next footstep location on-line during the motion continuously. This adjustment, which is found based on both pelvis and swing foot tracking errors, naturally takes the swing dynamics into account. Suggested adjustments are added to the Cartesian 3LP gaits and converted to joint-space trajectories through inverse kinematics. Fixed and adaptive foot lift strategies also ensure enough ground clearance in perturbed walking conditions. The proposed structure is robust, yet uses very simple state estimation and basic position tracking. We rely on the physical series elastic actuators to absorb impacts while introducing simple laws to compensate their tracking bias. Extensive experiments demonstrate the functionality of different control blocks and prove the effectiveness of time-projection in extreme push recovery scenarios. We also show self-produced and emergent walking gaits when the robot is subject to continuous dragging forces. These gaits feature dynamic walking robustness due to relatively soft springs in the ankles and avoiding any Zero Moment Point (ZMP) control in our proposed architecture.Comment: 20 pages journal pape

Medium Voltage Network Residual Earth Fault Current Estimation Methods

Extensive cabling during 2010s has drastically changed the earth fault behaviour of the rural area distribution network. Against the assumptions of traditional earth fault analysis, cable net-work zero sequence series impedance is nonnegligible, thus zero sequence voltage applied over the zero sequence impedance during an earth fault generates a resistive component to the earth fault current in addition to the capacitive component. In the resonant earthed neutral sys-tem, capacitive earth fault current can be compensated with inductive Petersen coils, but the resistive current component cannot be compensated with Petersen coils. Increase of resistive earth fault current will increase the absolute value of the residual earth fault current flowing to ground during the earth fault and consequently cause dangerous touch voltages. The reactive component of the residual earth fault current is mostly known but the resistive component is associated with multiple uncertainties. The harmonic component is out of the scope of this thesis and thus omitted. Due to the uncertainties, calculation of the resistive earth fault current has proven to be complicated, but if residual earth fault current is to be calculated accurately, the resistive component must be calculated or estimated first. The SFS 6001: 2018 standard states that if the residual earth fault current in resonant earthed neutral system is unknown the value can be assumed 10% of the network capacitive earth fault current. However, as extensive cabling increases resistive earth fault current production of the network, the validity of this assumption has caused concern. Therefore, the aim of this thesis was to develop a practically oriented model for estimating residual earth fault current that can easily be applied to multiple locations in the network. Secondly, the validity of the 10% assumption specified by the standard was studied in Elenia’s network. The network information system used in Elenia is currently unable to take into account the cable network zero sequence impedance, thus a statistical examination was performed based on network data from 45 primary transformer areas. The measurements from centralized Petersen coil regulators were utilized in the examination, since the regulators provide real-time measurement of the network resistive earth fault current production. In the statistical examination the dependency of resistive earth fault current from other network parameters was studied. The objective was to identify variables that correlate with resistive earth fault current, so that they could be used to estimate the resistive earth fault current. After the correlation analysis, correction factors were assigned to the variables and the results were compared to the measurements from the regulators. The conclusion was that the resistive earth fault current can be estimated to be 5% of the total capacitive earth fault current. This result was applied to residual earth fault current calculation and the obtained values were again compared to the values calculated from the measurements. There was only a minor difference, which implies that the developed model yields accurate results. More importantly, the developed model proved to provide more accurate results than the estimation method specified in SFS 6001, that acted as a reference. In addition, there are two alternative interpretations of the method specified in the standard, so depending on the interpretation, the results were either too high or too low when applied to Elenia’s network. However, the results of this thesis are heavily dependent on the properties of the network, thus results should only be applied to networks with similar configuration

Medium Voltage Network Residual Earth Fault Current Estimation Methods

Extensive cabling during 2010s has drastically changed the earth fault behaviour of the rural area distribution network. Against the assumptions of traditional earth fault analysis, cable net-work zero sequence series impedance is nonnegligible, thus zero sequence voltage applied over the zero sequence impedance during an earth fault generates a resistive component to the earth fault current in addition to the capacitive component. In the resonant earthed neutral sys-tem, capacitive earth fault current can be compensated with inductive Petersen coils, but the resistive current component cannot be compensated with Petersen coils. Increase of resistive earth fault current will increase the absolute value of the residual earth fault current flowing to ground during the earth fault and consequently cause dangerous touch voltages. The reactive component of the residual earth fault current is mostly known but the resistive component is associated with multiple uncertainties. The harmonic component is out of the scope of this thesis and thus omitted. Due to the uncertainties, calculation of the resistive earth fault current has proven to be complicated, but if residual earth fault current is to be calculated accurately, the resistive component must be calculated or estimated first. The SFS 6001: 2018 standard states that if the residual earth fault current in resonant earthed neutral system is unknown the value can be assumed 10% of the network capacitive earth fault current. However, as extensive cabling increases resistive earth fault current production of the network, the validity of this assumption has caused concern. Therefore, the aim of this thesis was to develop a practically oriented model for estimating residual earth fault current that can easily be applied to multiple locations in the network. Secondly, the validity of the 10% assumption specified by the standard was studied in Elenia’s network. The network information system used in Elenia is currently unable to take into account the cable network zero sequence impedance, thus a statistical examination was performed based on network data from 45 primary transformer areas. The measurements from centralized Petersen coil regulators were utilized in the examination, since the regulators provide real-time measurement of the network resistive earth fault current production. In the statistical examination the dependency of resistive earth fault current from other network parameters was studied. The objective was to identify variables that correlate with resistive earth fault current, so that they could be used to estimate the resistive earth fault current. After the correlation analysis, correction factors were assigned to the variables and the results were compared to the measurements from the regulators. The conclusion was that the resistive earth fault current can be estimated to be 5% of the total capacitive earth fault current. This result was applied to residual earth fault current calculation and the obtained values were again compared to the values calculated from the measurements. There was only a minor difference, which implies that the developed model yields accurate results. More importantly, the developed model proved to provide more accurate results than the estimation method specified in SFS 6001, that acted as a reference. In addition, there are two alternative interpretations of the method specified in the standard, so depending on the interpretation, the results were either too high or too low when applied to Elenia’s network. However, the results of this thesis are heavily dependent on the properties of the network, thus results should only be applied to networks with similar configuration

An Advanced Teaching Lab for the Setting up of an Islanded Production Unit

The present paper addre teaching lab consisting of setting up an is unit. This teaching lab takes place in the ve master level for students in electrical engin specialization. The purpose of this teaching knowledge learned in different areas such as control, electrical machines and networks, a of them in practice. The present paper des different steps followed by the student to production unit. Index Terms—Teaching Laboratory, Isl

STATCOM and SVC with Wind Turbines

The large wind parks are the feasible solution in order to generate clean energy compared with conventional power plants. Therefore, the interest in the Wind Energy Conversion System (WECS) is quickly increasing to reduce the fossil fuels dependencies. While the penetration of the WECS increases into the grid, many of the technical challenges have appeared. Low voltage Ride Through (LVRT) is the new requirement which needs to be fulfill when the amount of wind power generation increases, to be able to guarantee the power system reliability and stability. The voltage dips that result from faults in the grid can lead to a loss generation unit. According to the LVRT, WTs are required to be always connect during the fault, and to support the power system by supplying reactive power to ensure grid stability. The main purpose of the thesis was to investigate that how the LVRT of Doubly Fed Induction Generator (DFIG) based Wind Turbine Generator (WTG) can be enhanced using shunt connected Flexible AC Transmission System (FACTS) devices Static Synchronous Compensator (STATCOM) and Static Var Compensator (SVC). The theoretical background related to the LVRT enhancement using STATCOM and SVC is performed, and results are verified by the simulation model. This thesis is constructed in 5 Chapters, Chapter 1 gives an overview about the problems related to wind power. Chapter 2 explains the different grid codes and different topologies of the wind turbine technologies. Chapter 3 explains the working principle, construction and applications of the STATCOM and SVC. A comprehensive comparison between the STATCOM and SVC is also explained in this chapter. The operation of DFIG wind turbine during voltage dip is analyzed by using the simulation model in the next Chapter. In the first case, the effect of a three-phase fault on the power system was analyzed without using any compensation device. The LVRT requirements were not fulfilled without any compensation device. Therefore, in the second case, SVC was added in the model. Some improvement was observed in this case, but it was not enough to fulfill very strict LVRT requirements such as German Grid Codes (GGCs).Therefore, in the third case, SVC is replaced by STATCOM to meet the LVRT requirement of GGCs. In the last case, three different ratings of STATCOM were utilized to see the effect on the grid voltage and reactive power support by STATCOMs. The key findings of this thesis work are reported by Chapter 5

Neurofly 2008 abstracts : the 12th European Drosophila neurobiology conference 6-10 September 2008 Wuerzburg, Germany

This volume consists of a collection of conference abstracts

Design and implementation of an opportunistic network based on IEEE 802.15.4

Les xarxes de sensors sense fils constitueixen un dels principals àmbits on s'han focalitzat els esforços dels entorns acadèmics i de la indústria. Les xarxes de sensors sense fils possibiliten un ampli ventall d'aplicacions de control i monitorització, que permeten l'automatització de tasques i donen pas a nous paradigmes, com l'anomenada "intel·ligència ambiental", o "La Internet de les coses". Un dels escenaris d'interès dins de les xarxes de sensors, i també en altres tipus de xarxes, és el de les xarxes formades per dispositius que es mouen i que realitzen algun tipus de trajectòria repetitiva. Un exemple és el dels autobusos municipals, que segueixen una ruta preestablerta. Es pot aprofitar el fet que l'autobús passa tard o d'hora per tota la ruta, per recollir i transportar dades dels punts pels quals ha passat. En aquest tipus d'escenaris, es pot fer servir un encaminament anomenat oportunístic, que es basa en aprofitar la connectivitat entre els nodes en aquells moments en dos o més nodes són prou a prop. Aquest projecte proposa el disseny i implementació en dispositius reals IEEE 802.15.4 d'un sistema de xarxa oportunística per a la recollida de dades ambientals