Quality of the output power delivered from the utilities has become a major concern of the modern industries for the last decade. These power quality associated problems are voltage sag, surge, flicker, voltage imbalance, interruptions and harmonic problems. These power quality issues may cause problems to the industries ranging from malfunctioning of equipments to complete plant shut downs. Those power quality problems affect the microprocessor based loads, process equipments, sensitive electric components which are highly sensitive to voltage level fluctuations. It has been identified that power quality can be degraded both due to utility side abnormalities as well as the customer side abnormalities. To overcome the problems caused by customer side abnormalities so called custom power devices are connected closer to the load end. One such reliable customer power device used to address the voltage sag, swell problem is the Dynamic Voltage Restorer (DVR). It is a series connected custom power device, which is considered to be a cost effective alternative when compared with other commercially available voltage sag compensation devices. The main function of the DVR is to monitor the load voltage waveform constantly and if any sag or surge occurs, the balance (or excess) voltage is injected to (or absorbed from) the load voltage. To achieve the above functionality a reference voltage waveform has to be created which is similar in magnitude and phase angle to that of the supply voltage. Thereby during any abnormality of the voltage waveform it can be detected by comparing the reference and the actual voltage waveforms. A new control technique to detect and compensate for the single phase voltage sags is designed in this project. The simulation was checked in the EMTDC/PSCAD simulation software and has shown reliable results.

Since few years the electric vehicles draw the attention. The battery technology’s continual improvements and incentives from the authorities guarantee them an assured future with a fast and considerable development. Some figures are forecasted by 2020: one or two millions electric vehicles. This could mean a huge increase in electricity consumption. The consequences on the total energy consumption have already been analyzed, however studies on the impact on the load curve remain scarce. In this context, this master thesis focuses on the impact of the electric vehicles’ charge on the French load curve and the production and consumption balancing. The grid issues are not studied here. The first part presents the state of the art in battery and electric vehicle technology, as well as battery charge’s characteristics. Besides the French traffic data are studied, in order to build the most realistic model as possible. The second part explains the principle of the modeling. A general and flexible model for the French fleet is built. This model can simulate the times of charge of a vehicle, and the state of charge of its battery, in order to get a total load curve for several days for an electric fleet. And finally, the different load curves are analyzed as well as their impacts on the electric balancing system and the possible solutions to lower these impacts. As the peak load for the electric vehicles’ charge corresponds to the total consumption peak in the evening according to the most probable scenario, services have to be implemented to reduce or put back the overload due to the electric vehicles. Those services (tariff signals regulations, battery management system, cut-off injunctions) have been tested. A model for grid injections during peak hours has also been developed, in order to help the electric system, and erase the electric vehicles’ impact on the load curve. Studies for the optimum load, the reserves and the margins are also suggested as well as other possible studies, such as EV’s carbon footprint. The reflections and strategies developed in this master thesis don’t reflect RTE’s policy and don’t commit the company.

Modern electric power system is very complex and undergoes unforeseen rapid changes in terms of demand/generation patterns and trading activities that hinder the system security. For example, a steep rise in load or a certain critical line/equipment outage can cause line overload or undesirable voltage profile and such events can push the system towards instability and possibly even a black out. In order to cope with such situations, it is common practice to purchase the rights of asking for a reduction of load from certain customers. However, it is not an ideal situation from reliability perspective, financial as well as having critical load in the power system. Load curtailment is the collection of control strategies employed to reduce the electric power loading in the system and main aim is to push the disturbed system towards a new equilibrium state. Load curtailment may be required even when voltages at some buses are out of their safe operating limits, to prevent a possible voltage collapse. Flexible AC Transmission Systems (FACTS) controllers could be a suitable alternative to provide reactive power support at the load centres locally and hence keep the voltages within their safe operating limits. Due to high costs of FACTS devices, their proper location in the system must be ascertained. To deal with the above problem a new methodology has been proposed, in this thesis, in terms of sensitivity factors for the optimal location of Static Var Compensator (SVC) to minimize the system load curtailment requirements for maintaining the system security. In this work, SVC has been considered for the study to minimize the load curtailment. The effectiveness of the proposed method has been tested on IEEE 14-bus and practical 75-bus Indian systems. Optimal placement have been obtained for the base case loading and to verify its locations, an Optimal Power Flow (OPF) problem has been formulated with an objective to minimize the load curtailment and satisfying all operating constraints along with optimal settings of SVC which is used at suggested places from developed methodology. Moreover, the effects of SVC on load curtailment reduction, which are located at base case loading, have also been investigated for different operating conditions e.g., increased load or having different contractual obligation in the system.

This master thesis was initiated with the aim to answer at what level of installed capacity of wind power in the northern parts of Sweden it would be beneficial to improve the transmission capacity from the northern Sweden. During the process of this work the aim has changed to try and create a model that can be used to analyze how well the hydro power installed in the northern Sweden can even out the quick changes in wind power production. To create a good model of all hydro power in northern Sweden is a very large job, unfortunately too large for a master thesis. This report therefore ends with an extensive analysis of the simplifications that have been made and their effects as well as a list of the future work that has to be done. The model that has been created have shown to be effective and produce good results. The conclusions that can be made is that the northern Swedish hydro power have very good possibilities to balance the wind power production. Only a few cases where water have been spilled even though there has been some free capacity has been discovered. Also the scenarios where a large amount of spilled water occurred can be cancelled by altering the seasonal planning of the hydro power stations. This master thesis has been made in close cooperation with Andreas Fagerberg, whose report (19) is often referred to in this text.

This thesis concerns how the power quality in the grid is affected by the connection of wind power plants. As things are at present, Fortum Distribution AB has a number of wind turbines and wind parks connected to the own grid. As the pressure on building and connecting additional wind power is increasing, so is also the interest of how the already existing wind power generation affects the power quality in the nearby distribution grids. The study is performed by direction of Fortum Distribution AB and is limited to the 10 kV/40 kV-grid in Bohuslän, Sweden. The methods for calculation of power quality are compared to the results of a number of measurements. Also, the power quality parameters flicker, harmonics, unbalance and voltage variations are compared to regulated limits. Long term voltage variations and flicker emission levels have been calculated from simulation results obtained in PowerGrid and PSS®E at seven different locations where wind power plants are connected. Partly from these calculations, four different points for measurements are selected. The calculation results are subsequently compared to measurement data from the four different locations. Besides flicker and long term voltage variations, the parameters harmonics, unbalance and short term voltage variations have been registered and analyzed. The largest wind park to be analyzed contains six turbines at 2.5 MW of marked power each, connected to the 40 kV-grid. The individual turbines to be analyzed generate a maximum of 0.75 MW each and are connected directly to the 10 kV-grid. Measurement results are compared to limits regulated in AMP and ASP which contains instructions and demands for connecting different production plants to the Swedish power grid. The results indicate an overall good power quality, however the flicker emission level exceeds the limits in all points of measuring. The theoretical calculations have proven to give a good estimation of the reality, but the calculation methods always provide a lower level of flicker emission than there is in the reality. This is because of a basic flicker level in the grid originating from other sources than the wind power plant. The calculation of voltage variations tends to give higher values in the calculations than in reality. This is partly a consequence of the tap changers in the transformers which keep the voltage a good level and partly a result of calculating for an extreme situation that never does occur during the measurements.

This report deals with the load duration curves used for development studies on the sub-transmission grid. The aims of grid development studies are firstly to locate the needs for grid reinforcement, then to elaborate a reinforcement strategy and finally to promote the profitability of this reinforcement. This study is about the last step of grid development studies: benefits calculation. The profitability of grid development studies is estimated by comparing grid investment costs and failure costs modelled by the energy not supplied. Load duration curves are used to calculate the energy not supplied due to transmission limitations and therefore to promote the profitability of grid developments (new transmission facilities…). Current load duration curves come from a catalogue created in the early nineties which identifies nine consumption profiles. The aim of this study was to decide whether this catalogue is still valid or not, and, if this catalogue is no longer valid, to elaborate a new catalogue or a homemade software to create on demand, i.e. “à la carte”, load duration curves or load curves for every studied area. Firstly, current catalogue relevance has been analyzed through comparisons with real measured load duration curves of fourteen areas which showed its inadequacy. Then, the study of the real measured load duration curves proved that an accurate catalogue including all the existing load profiles would require a huge number of parameters to describe it. Therefore, a new simple catalogue could be enough to model load profiles on large areas for large scale studies but not for local studies. For these last ones, on demand load duration curves would be preferred to have an appropriate detailed and realistic description of local load behaviour. Finally, a simple method and software to create load duration curves or load curves for every studied area has been developed. Through this analysis, questions were raised of which some could not be answered and this method is not applicable right now. The study needs to be widened in order to establish the links with load levels forecast.

International agreements have set high demands on the share of renewable energy in the total energy mix. From the different renewable sources, significant investments are made in wind power. More and more wind turbines are being built and their number is due to rise dramatically. There are many different generator technologies, but this paper focuses on the doubly-fed induction generator (DFIG). DFIGs are generators which are connected to the grid on both stator and rotor sides. The machine is controlled via converters connected between the rotor and the grid. The size of these converters determines the speed range of the DFIG. Wind farm connections to the grid must satisfy grid requirements set by transmission system operators. This means that the study of their dynamic responses to disturbances has become a critical issue, and is becoming increasingly important for induction generators, due to their growing size and number. Several computer programs exist to carry out dynamical simulations and this work will focus on one of them, namely Power Factory from DigSilent. It offers a large choice of builtin components. These components can be controlled through input signals. It is therefore possible for the user to design control strategies. Power Factory has two models of DFIG. A new model has also been developed, based upon a controllable voltage source. These three models are compared, in terms of dynamical behavior and simulation time. One is then used to study the effect of introducing a certain signal to the control strategy.

In the French liberalised electricity market, the Distribution Network Operators (DNOs) and the Transmission Network Operator (TNO) are both financed by an access fee paid by any client connected to their network. Within this frame, any DNO’s is a client of the TNO as a user of the transmission grid. It is regulated by the French Government, following the recommendation of the national energy regulation committee (CRE). The access fee to the transmission network is a major expenditure for ERDF, the national DNO. It is also a rather new matter of concern since the electrical system was previously vertically integrated. One aim of this master thesis is to feed the evolutions of ERDF’s cost control strategy. In order to emphasize the academic interest, this report takes the point of view of a DNO looking for the best behaviour in response to the regulatory frame, based on ERDF’s example. In addition to that, it provides an introduction to this specific piece of regulation and it should bring new elements toward a better understanding of the access fee behaviour. The regulation, decided for at least the four years following the master thesis, is taken as an assumption in this study. This present report is solely the result of the author’s personal interpretation, including when referring to ERDF’s strategy. The reflections, perspectives and propositions do not commit thencompany.

It is well known that transmission investment yields two major bene_ts: (a) it allows cheaper remote generation to substitute for more expensive local generation, (the e_ciency bene_t) and (b) by increasing the diversi_cation of uncorrelated generation sources, allows a reduction in the volume of balancing services required (the diversi_cation bene_t). Conventional transmission planning processes tend to focus exclusively on the e_ciency bene_t. It is well known that increasing wind penetration increases the need for balancing services. Even where the market is able to provide the signals to generators as to when and how much to produce, increasing wind penetration increases the need for higher-exibility plant (such as OCGT or very fast start hydro plant) which typically has a higher long-run cost. The purpose of this study is to develop a mathematical model for quantifying the diversi_cation bene_t for transmission investment. To do this two-step economic dispatch of the day-ahead energy market and the real-time balancing market are mathematically formulated in a single optimization problem which calculates the results of day-ahead market dispatch and real-time market dispatch in one optimization problem. The new formulation is a linear programming problem which calculates the dispatch cost and the economic deviation from the dispatch cost. Firstly, this single optimization problem is used for quantifying the diversi_cation bene_t of the additional transmission capacity. Then, a stochastic optimization model for modeling the diversi_cation bene_t of additional transmission capacity in the transmission planning process is formulated. Uncertainty of system parameters are modeled using scenarios. ARIMA models and a scenario reduction technique based on Kantorovich distance are used for generating the scenarios. To explain the diversi_cation bene_t, two example systems are studied. Firstly, to evaluate the impact of additional transmission capacity on the dispatch cost of the day-ahead energy market and the real-time balancing market, IEEE thirty-node example system is studied. The diversi_cation bene_t is calculated and the conclusions are extracted. Then, a transmission planning approach, which considers the diversi_cation bene_t along with the e_ciency bene_t, is proposed. The proposed and conventional transmission planning approaches are applied to modi_ed IEEE 24- node example system. Conventional transmission planning approach (which models only e_ciency bene_t in its formulation) is used as a benchmark in this study. The numerical results show that the proposed approach can e_ectively quantify the diversi_cation bene_t of additional transmission capacity.

bad format, retyped Both wind power and hydro power must be built in immediate proximity to the source. Almost all hydro power is concentrated in the north of Sweden, since the largest rivers can be found here. The northern parts of Sweden also have good wind conditions and are therefore interesting for wind power projects. The transmission system in such areas may not have the sufficient capacity for additional power production, which calls for some kind of coordinated regulation between the hydro power producer and the wind power producer, in order to not produce more than can be transferred. A strategy for how to coordinate both power productions will avoid an expensive reinforcement of the net. In this thesis different strategies for coordinated regulation are studied and simulated using a linear programming model (LP). The major planning objective is to keep production goals and physically constraints of the power system. A model including objective function and constraints are presented for each strategy. Computational results are reported showing that both sides benefit from the coordination strategies and a better utilization of the transmission net.