Arash Jamehbozorg

A Decision Tree-Based Method for Fault Classification in Double-Circuit Transmission Lines

In this paper, a novel method for fault classification of double-circuit transmission lines is presented. The proposed method needs voltages and currents of only one side of the protected line. After detecting the exact time of fault inception and calculating the odd harmonics of the measured signals, up to the nineteenth, a decision tree algorithm has been employed for recognition of the intercircuit fault type. Also, the proposed method is extended for classification of crossover faults in these transmission lines. Simulation results have shown that the proposed method can classify the faults in less than a quarter of a cycle with the highest possible accuracy.In this paper, a novel method for fault classification in single-circuit transmission lines is presented. The proposed method needs voltages and currents of only one side of the protected line. After detecting the exact time of fault inception, the fault type is recognized by means of a decision-tree algorithm (DT) which is formerly trained by applying the odd harmonics of the measured signals, up to the 19th. Simulation results have shown that the proposed method can classify the faults in less than a quarter of a cycle with highest possible accuracy.

Small Signal Analysis of Power Systems With Wind and Energy Storage Units

A study of small signal behavior of power systems including wind generation units and energy capacitor systems (ECSs) is presented in this paper. Modeling of wind units with squirrel-cage induction generators connected to power system through a full-scale AC/AC converter and ECS unit are explained thoroughly. The ECS unit (considered in this paper) consists of electric double-layer capacitors (EDLC) and DC/AC converter. Small signal behavior of three test systems are studied and compared with one another using digital computer simulations. The three systems are: S1) WSCC 9-bus system with three conventional synchronous generators (SGs), S2) the WSCC system with one of the conventional SGs replaced by a wind energy system, and S3) the same as S2) but with the addition of an ECS unit. The study includes comparing of dominant eigenvalues, the participant state variables, and the related participation factors for the three systems. In addition, the effects of loading on the unstable modes of the system with conventional SG, wind and ECS units (system S3) are studied using the trajectory of these modes as loads are increased.

Optimum reactive power compensation regime for radial connected wind turbines

Although there is considerable progress in the wind energy conversion technology, most of the currently installed wind turbines are using induction generators to convert mechanical energy to electrical one. The induction generators which are utilized in wind turbines and wind farms consume high amount of reactive power. Beside, since there is no voltage regulation installed for induction machines and they draw reactive power from power system, these machines are source of voltage fluctuations. Therefore, reactive power compensation is needed to provide expected voltage support where the wind turbines are connected. Minimizing the cost of compensation is the next important step. In this paper a practical method is proposed to find the minimum cost of reactive power compensation for use in radial connection of wind power turbines to power systems.

PV Output Power Smoothing Using Energy Capacitor System

Photovoltaic systems are being considered as one of the major sources of electrical energy for next decades. The cost of PV cells is decreasing more and more and this will help increase its penetration in power systems. One of the main issues of PV systems is their dependency on irradiance of the sun and temperature of the cells. As during day-time both these factors are changing continuously, the output power of PV cells would have considerable fluctuations that would not be acceptable in power systems with high penetration of PVs. In order to solve this problem, this paper proposes a system to smooth the output power of the PV using Energy Capacitor System. A case study for investigating the performance of the proposed configuration is simulated and results show that it can considerably smooth the output power of the PV system.

A decision tree based method for fault classification in transmission lines

In this paper a novel and accurate method is proposed for fault classification in transmission lines. The method is based on decision tree and gets the 50 up to 950 Hz phasors of voltages and currents from one end of the line, as the inputs. The method is applied to a 400 kV transmission line, and the results showed the highest possible accuracy within less than quarter of a cycle after fault inception.

A new controller design for a synchronous generator-based variable-speed wind turbine

This paper presents a control scheme for full-scale back to back converter used for connecting the synchronous generator-based variable speed wind turbine to grid. The new control concept is based on the q-d reference modulation indices of the Discontinuous Pulse Width Modulation (DPWM) technique. The converter consists of a six-diode rectifier and a six-IGBT voltage source inverter with a dc-link in between. Modeling of the whole system is presented in PSCAD/EMTDC software and steady-state and fault conditions of the system are investigated. Results show that the controller can appropriately control the converter of the wind turbine system in steady-state and fault conditions.

A wide-area SVC controller design using a dynamic equivalent model of WECC

In our recent work [1] we constructed a reduced-order five-area model of the Western Electricity Coordinating Council (WECC) power system using mathematically derived parameters from real PMU data. These parameters include inter and intra-area impedances, inertias, and damping values for aggregate machines representing five geographic areas. In this paper we use this reduced-order model as a tool to design an SVC controller to damp the inter-machine oscillation modes, which in the full-order model corresponds to inter-area oscillations. The controller input is chosen via statistical variance analysis, and its parameters are tuned to improve slow mode damping. The model is implemented in a real-time digital simulator, and emulated for various disturbance scenarios to illustrate the effectiveness of the SVC using a metric for dynamic performance. The resulting closed-loop response is promising in aiding damping of inter-area modes in the WECC, especially at a time of increasing penetration of wind and other renewable resources.

A MATLAB GUI package for studying small signal characteristics of power systems with wind and energy storage units as an education tool

This paper presents a MATLAB Graphical User Interface (GUI) software package which enables users to study small signal behavior of power systems with wind unit and Energy Capacitor Systems (ECSs). For hybrid systems including wind and storage units, studying dynamic behavior of overall system is a complicated and time consuming task. The objective of this paper is to design a user friendly GUI as an educational tool that helps students study the effect of wind and storage units on power system. Modeling of wind units with squirrel-cage induction generators connected to the network through a full-scale AC/AC converter and ECS units consisting of Electric Double-Layer Capacitors and DC/AC converter are explained thoroughly. GUI let the users to choose load change disturbance in any bus or wind speed change in any wind unit and displays the variation of desired state variable after such disturbance.

Dynamic studies of multi-machine power systems integrated with large Photovoltaic power plants

This paper presents dynamic analysis of multi-machine power systems with large penetration of Photovoltaic (PV) units. The actual non-linear characteristics of the PV-units is included in the modeling of the overall power system and the influence of this non-linear dynamics is studied through various simulations. These simulations (performed in MATLAB Simulink software package) are applied on a modified IEEE 30-bus system, where one of the major generators is replaced by a large PV power plant. Three case studies are considered. From these studies it is concluded that large penetration of PV-units deteriorates the dynamics of the overall system.

Enhancement of micro-grid dynamics in presence of wind units using Energy Capacitor Systems

This paper proposes an Energy Capacitor System (ECS) designed to enhance the dynamics of micro-grids in presence of wind generation units. The output power of wind units fluctuates due to continuous variations in wind speed. In a power system with high penetration of wind units - like a microgrid - this can considerably deteriorate the dynamics of the entire system. To study the negative impacts of high penetration of wind power on power system dynamics and compensation of this negative impact through ECS, the following tasks are undertaken in this paper. First, a micro grid test system is modeled using MATLAB Simulink software. Then, an ECS unit is designed to mitigate the negative effects caused by the wind unit due to wind speed fluctuations. Finally, the dynamics of the test system for a short-circuit fault is studied. The simulation results show that ECS units can effectively improve the dynamics of the system, thus compensating for negative effects of wind speed fluctuations (in normal steady state operation) and during/after a major short circuit fault.