gunne hegglid - Academia.edu (original) (raw)

Papers by gunne hegglid

27th International Conference on Electricity Distribution (CIRED 2023)

Linköping Electronic Conference Proceedings

Extreme black-swan occurrences like earthquakes, glacial lake outbursts, flash floods, landslides... more Extreme black-swan occurrences like earthquakes, glacial lake outbursts, flash floods, landslides, etc. are important concerns in Himalayan countries like Nepal, which are highly susceptible, geologically active, and exquisitely fragile. Nepal generates 97 percent of its electricity from hydropower, where 56.08 percent of it is coming from seasonal run-off-river (RoR) hydro plants. Landslides and mudflows are common in the monsoon, and low discharge is common in the winter season. These RoR plants must be able to withstand high-impact events like earthquakes and lengthy droughts in order for the Nepalese grid to remain secure. This study gives a presentation and overview of previously occured natural hazards in Nepal related to hydropower plants. In particular, the 2014 Sunkoshi landslide and the 2021 Melamchi flood are evaluated as extreme events and their impacts on hydropower plant has been studied. In addition, an in-depth investigation on a ROR plant is carried out. Moreover, t...

2019 7th International Youth Conference on Energy (IYCE)

Optimal power dispatch (OPD) problems has a major role in security and flexibility of power syste... more Optimal power dispatch (OPD) problems has a major role in security and flexibility of power systems. It is useful to enhance the voltage stability, minimization the power losses and improvement of voltage profile. In recent years, several methodologies based on computer algorithms and mathematical formulation have been proposed for solving optimal reactive power dispatch. The techniques are classified based on conventional and intelligent methods. The objective of this paper is minimization the power losses using intelligent algorithms like Particle Swarm Optimization method and conventional method like Newton Raphson. Particle Swarm Optimization (PSO) is based on the simulation the act of group of fishes or birds in searching space for finding optimal solution as the piece of food. The proposed algorithms are analyzed on the Nordic 44 system. The results of simulation show the reduction of total power losses using intelligent method. The proposed methods are tested on Nordic 44 test system, IEEE 9 buses, 14 buses, and 30 buses.

Optimal power flow plays a vital role in providing secure, economic, and reliable operation of el... more Optimal power flow plays a vital role in providing secure, economic, and reliable operation of electrical power system. This paper presents a comparison of two types of intelligent algorithms for solving optimal power flow problems, incorporating Flexible AC transmission systems (FACTS) devices. Particle Swarm optimization (PSO) and imperialist competitive algorithm (ICA) have been analyzed and simulated with MATLAB software in order to reduce the total power losses of the network with three types of FACTS devices: unified power flow controller (UPFC), Static Var Compensators (SVC), and Thyristor Controlled Series Capacitor (TCSC). The proposed approach is simulated in IEEE-30 buses in MATLAB software and the results are compared with several tables and diagrams. It is observed that PSO algorithm with UPFC as the FACTS devices can reduce more active and reactive power losses than the other types of the FACTS devices and intelligent algorithms. IEEE 30 buses is used to illustrate the...

This paper describes the Fault Ride Through (FRT) capability of generators of a part of the 132 k... more This paper describes the Fault Ride Through (FRT) capability of generators of a part of the 132 kV high voltage power network in Telemark region, Norway using a simplified power system simulator model. The organization, “European network of transmission system operators for electricity” (ENTSO-e) is introducing a network code for the Transmission System Operators (TSO) in Europe where the upper limit of the FRT requirement for 132 kV system is 0.25 s. However, according to the Norwegian network code, this limit is 0.40 s. The generators in the Norwegian power system are located in a distributed network and most of these are hydropower generators. The simulation results show that the structure of the Nordic power system enhances the system stability. The dynamic model of the power network is developed by using DIgSILENT PowerFactory simulation tool.

This paper is concerned with power system modeling using the Modelica language in comparison to a... more This paper is concerned with power system modeling using the Modelica language in comparison to a traditional simulation tool. Though most common power system simulation tools are computationally efficient and reasonably user-friendly, they have a closed architecture. Thus, there is motivation to use an open-source modeling language to describe electric networks, such as Modelica. A well-established benchmark for power system studies was analyzed. Regarding the voltage as a function of time, a reasonable agreement was found between the simulation results of the used simulation tools for long-term voltage stability. However, a comparison of faster electromechanical mechanisms, such as rotor angle stability, demands more detailed models in the Modelica tool.

IFAC-PapersOnLine, 2020

Optimal power flow is a nonlinear optimization method to enhance the performance and flexibility ... more Optimal power flow is a nonlinear optimization method to enhance the performance and flexibility of a power system. This paper explores the use of particle swarm optimization (PSO) algorithm as an artificial intelligence technique to solve a single objective function of the optimal power flow problem. The objective function is the minimization of the transmission power losses by keeping the equality and inequality constraints on their secure limits. To test the effectiveness of the proposed method, different scenarios of the Nordic 44 model include maximum import to Norway and maximum export from Norway to the other Nordic networks, as well as hourly load data variations are tested with MATLAB software. The Nordic 44 model is the test system that has been used to analyze stability and control problems that are relevant to the Nordic power network. The test results show the convergence and effectiveness of the proposed method to solve OPF problem compared to Genetic Algorithm (GA) as intelligent method and OPF by MATPOWER as the other classical method to test convergence and effectiveness of the proposed method to solve OPF problem under various load cases (heavy and light loading) of Nordic 44 test system.

2021 IEEE Madrid PowerTech, 2021

This paper presents a new 21-bus power system model developed using the simulation software ‘DIgS... more This paper presents a new 21-bus power system model developed using the simulation software ‘DIgSILENT PowerFactory’ representing the reduced Norwegian power transmission network. The network includes a 132 kV regional network and a 420 kV transmission network to visualize local and inter-area modes of oscillations. The network data is adopted from the benchmark model ‘Nordic 44’. The model is validated by analyzing some of the static and dynamic simulation results recommended by IEEE task force for the benchmark models. The presented model is recommended to use teaching power system dynamics for new electrical engineers.

Proceedings of The 9th EUROSIM Congress on Modelling and Simulation, EUROSIM 2016, The 57th SIMS Conference on Simulation and Modelling SIMS 2016, Dec 19, 2018

This paper describes a Model Predictive Control (MPC) system for voltage control through field ex... more This paper describes a Model Predictive Control (MPC) system for voltage control through field excitation of hydroelectric generating units. An attractive feature of MPC is its capability to handle Multiple Input, Multiple Output (MIMO) systems and nonlinear systems taking constraints into account. The system under study is a power system based on detailed models from Matlab's SimPowerSystems TM and parametrized according to the Nordic model from the Norwegian Transmission System Operator (TSO), Statnett. The primary role of the field excitation control system is to quickly respond to voltage disturbances occurring in the power system. The control system is tested for both first-swing transient stability and long term voltage stability.

IEEE Transactions on Power Systems, 2019

The ever-increasing penetration of intermittent energy sources introduces new demanding operating... more The ever-increasing penetration of intermittent energy sources introduces new demanding operating regimes for the bulk power generation in the power grid. During a worstcase power system disturbance scenario, the generator needs to operate beyond its limits to maintain stable operation. Therefore, a new online low-order thermal model of a hydrogenerator has been recently proposed, where the periodic extension of the long-forgotten capability diagram of the machine was in-depth investigated. An increased performance can be obtained if the total thermal capacity of the generator is exploited by applying optimal control theory in the Automatic Voltage Regulator (AVR). This paper proposes a Non-linear Model Predictive Controller (NMPC) combined with an Unscented Kalman Filter (UKF) with a modeling framework geared for use in a supervisory control structure for the conventional control system. The method provides maximum utilization of the machine's thermal capacity by providing the controller with an Enhanced Capability Diagram (ECD). Case studies on a single-machine system and a 16-bus multi-machine system were investigated. The results show that a satisfying controller action during different long-term voltage instability scenarios is realized.

Journal of High Speed Networks, 2019

Optimal power flow (OPF) problems play a central role in planning and operating a transmission po... more Optimal power flow (OPF) problems play a central role in planning and operating a transmission power system in a reliable, flexible and secure manner. In this paper, a significant intelligent algorithm based on the Particle Swarm Optimization method is proposed for solving the optimal reactive power dispatch (ORPD) problem by adjusting equality and inequality constraints. The objective function which is considered for optimal active and reactive power dispatch is the minimization of transmission power losses. In order to solve ORPD problems, Particle Swarm Optimization (PSO) based on the Newton Raphson method is coded with MATLAB software and the results of the simulation are compared to the Interior Point method as the classical method for minimization transmission losses in the Nordic 44 system. The Nordic 44 system consists of three countries, including Norway, Finland, and Sweden, and has 44 buses, 67 branches and 61 generators. The results illustrate the effectiveness of the proposed algorithm compared to the other methods for the minimization of total power losses for Nordic 44. The simulation results of the proposed method for the Nordic 44 system are compared to the results of the PSO algorithm for the ORPD problem in several networks, including IEEE 14 buses, 30 buses, and 57 buses.

IEEE Transactions on Industrial Electronics, 2018

The flexible generation of electrical energy is heavily dependent on hydropower. Advanced control... more The flexible generation of electrical energy is heavily dependent on hydropower. Advanced control systems may offer an enhanced operational security. During power system disturbances, a generator may need to operate beyond its limits to maintain a stable operation. This increased performance can be obtained if the total thermal capacity of the generator is exploited by applying optimal control theory in the automatic voltage regulator (AVR). A low order model is required for online implementation and prediction of critical thermal stresses in the machine. Periodic extension of the generator capability diagram has been historically overlooked. In this contribution, a thermal network for air-cooled hydrogenerators for use in real-time monitoring and optimal control is proposed and validated. The thermal model is extended with a heat exchanger model. The dynamic model is developed from an energy balance of the system and verified through FEM simulations and temperature measurements in a case study. Transient simulation results of the online low order model are in good agreement with measurements. Finally, a satisfactory simulator speed is obtained which confirms the feasibility of this approach in real-world applications.

Modeling, Identification and Control: A Norwegian Research Bulletin, 1983

IFAC-PapersOnLine, 2018

Design and operating criteria for power system stability largely depend on a synchronous generato... more Design and operating criteria for power system stability largely depend on a synchronous generator's capability to remain in synchronism. In the field of mathematical modeling of the dynamics of synchronous generator's with excitation systems, there is a need for more practical studies investigating the impact of Fault Ride Through criteria from system operators on actual cases. This paper describes a practical method which illustrates the different aspects of how this type of modeling and simulation can be carried out on a case study. Results show that the type of excitation system, time of fault, and the generators rotating mass have large impact on the system stability.