| 1. |
- Arafat, Yasir, 1985, et al.
(författare)
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On Possibilities of Using Smart Meters for Emergency Grid Management : Analysing the Effect on Power Quality
- 2015
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Ingår i: 2015 IEEE INNOVATIVE SMART GRID TECHNOLOGIES - ASIA (ISGT ASIA). - 9781509012374
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Konferensbidrag (refereegranskat)abstract
- Electricity grids worldwide are continuing to be severely constrained and stretched to capacity. Certain grid conditions e.g., peak load crisis or loss of generation may lead to severe under frequency situations. Load shedding can then be useful to prevent the national grid from being overwhelmed. Typically, load shedding is done from medium voltage substation level and all customers including emergency service providers under that substation lose power. However, it is beneficial for a society to exclude emergency service providers from load shedding. Smart Meters (SMs) are generally equipped with remotely accessible switch which gives a unique opportunity to exclude prioritized customers during emergency load shedding. Distribution System Operators (DSOs) are currently using remote SM switching typically for one customer at a time. However, the SM switching technique has not been fully investigated with regard to multiple customers. In order to fulfill the gap, this paper presents results obtained from field tests on simultaneous multiple SMs switching with a main focus on the impact of multiple SMs switching on Power Quality (PQ). The results show that impact on PQ might be negligible for small number of SMs switching. Moreover, faster SMs switching and reliable communication system is found as an important prerequisite to use SMs for emergency load shedding.
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| 2. |
- Arafat, Yasir, 1985, et al.
(författare)
-
Possibilities of demand side management with Smart Meters
- 2015
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Ingår i: International Conference on Electricity Distribution, CIRED 2015.
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Konferensbidrag (refereegranskat)abstract
- There are problems with congestion during peak electricity demand periods for today’s grid infrastructure. As the demand has been sharply increasing day by day, the power reserve, as it is designed today, may be gradually phased out. Demand side management (DSM) can then be necessary to keep balance between the demand and the supply. By using Smart Meters (SMs), the Distribution System Operator (DSO) can manage the demand side during peak load crisis and decrease the risk of blackouts. The SM may allow the DSO to switch loads in an area using a customer’s prioritize list, while excluding emergency service providers and critical customers from switching. Moreover, switching multiple SMs at a time might have impact on the Power Quality (PQ) of the grid. This paper presents results from field test on multiple SMs switching and investigated the impact of SMs switching on the PQ of the electricity grid.
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| 3. |
- Arafat, Yasir, 1985, et al.
(författare)
-
Remote switching of multiple smart meters and steps to check the effect on the grid's power quality
- 2014
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Ingår i: 2014 IEEE/PES Transmission and Distribution Conference and Exposition, T and D 2014; Chicago; United States; 14 April 2014 through 17 April 2014. - 2160-8563. - 9781479936557 ; , s. Art. no. 6863273-
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Konferensbidrag (refereegranskat)abstract
- The traditional electrical grid is transitioning into the Smart Grid (SG) and the introduction of Smart Meter (SM) is a first stage towards Smart Grid. The SM can offer new functionalities such as remote reading, automatic event reporting and the possibility of remote switching by the Distribution System Operator (DSO). The DSO can send remote signal to the breaker of the SM to disconnect or connect customers. This could be used when customers are moving or do not have a contract. DSO is currently applying this technique regularly for customers but one by one which do not affect the grid's power quality remarkably. But this technique has never been applied for multiple customers at a time in a single neighborhood and the possible effect on the grid's power quality is still unknown. This condition is studied in this paper through test scenarios which have already been planned to test. This paper presents necessary steps of remote SM switching for a large number of customers. Power quality standards and steps for measuring power quality during the tests are outlined. Possible risks of the test as well as the probability of occurring risk and also the consequences of those risks are studied in this paper.
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| 4. |
- Axelsson, Patrik, 1985-
(författare)
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On Sensor Fusion Applied to Industrial Manipulators
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the main tasks for an industrial robot is to move the end-effector in a predefined path with a specified velocity and acceleration. Different applications have different requirements of the performance. For some applications it is essential that the tracking error is extremely low, whereas other applications require a time optimal tracking. Independent of the application, the controller is a crucial part of the robot system. The most common controller configuration uses only measurements of the motor angular positions and velocities, instead of the position and velocity of the end-effector.The development of new cost optimised robots have introduced unwanted flexibilities in the joints and the links. It is no longer possible to get the desired performance and robustness by only measuring the motor angular positions. This thesis investigates if it is possible to estimate the end-effector position when an accelerometer is mounted at the end-effector. The main focus is to investigate Bayesian estimation methods for state estimation, here represented by the extended Kalman filter (EKF) and the particle filter (PF).A simulation study is performed on a two degrees of freedom industrial robot model using an EKF. The study emphasises three important problems to take care of in order to get a good performance. The first one is related to model errors which in general requires better identification methods. The second problem is about tuning of the EKF, i.e., the choice of covariance matrices for the measurement and process noise. It is desirable to have an automatic tuning procedure which minimises the estimation error and is robust to initial conditions of the tuned parameters. A variant of the expectation maximisation (EM) algorithm is proposed for estimation of the process noise covariance matrix Q. The EM algorithm iteratively estimates the unobserved state sequence and the matrix Q based on the observations of the process, where the extended Kalman smoother (EKS) is the instrument to find the unobserved state sequence.The third problem considers the orientation and position of the accelerometer mounted to the end-effector. A novel method to find the orientation and position of the triaxial accelerometer is proposed and evaluated on experimental data. The method consists of two consecutive steps, where the first is to estimate the orientation of the sensor from static experiments. In the second step the sensor position relative to the robot base is identified using sensor readings when the sensor moves in a circular path and where the sensor orientation is kept constant in a path fixed coordinate system.Finally, experimental evaluations are performed on an ABB IRB4600 robot. Different observers using the EKF, EKS and PF with different estimation models are proposed. The estimated paths are compared to the true path measured by a laser tracking system. There is no significant difference in performance between the six observers. Instead, execution time, model complexities and implementation issues have to be considered when choosing the method.
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| 5. |
- Bergh, Andreas, et al.
(författare)
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Municipally Owned Enterprises as Danger Zones for Corruption? : How Politicians Having Feet in Two Camps May Undermine Conditions for Accountabilit
- 2019
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Ingår i: Public Integrity. - : Routledge. - 1099-9922 .- 1558-0989. ; 21:3, s. 320-352
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Tidskriftsartikel (refereegranskat)abstract
- The market-inspired reforms of New Public Management have been particularly pronounced in Swedish local government. Notably, municipally owned enterprises (MOEs) have rapidly grown in numbers. Principal-agent theory gives rise to the hypothesis that the massive introduction of MOEs has impacted negatively on the conditions for accountability in Swedish local government. To study this, social network analysis was employed in mapping networks for 223 MOEs in 11 strategically chosen municipalities, covering a total of 732 politicians. The analysis reveals substantial overlaps between principals (representatives of the ultimate stakeholders, citizens) and agents (the boards of the MOEs). Hence, corporatization of public services seems to imply worrisome entanglements between the politicians who are set to steer, govern, and oversee MOEs on the one hand, and the board members of MOEs on the other. The increasing numbers of MOEs may therefore have adverse effects on accountability in important and growing parts of Swedish local government.
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| 6. |
- Gustafsson, Anders, 1985-
(författare)
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Bråkmakaren
- 2017
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Ingår i: Axess. - Stockholm : Axess publishing. - 1651-0941.
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 7. |
- Gustafsson, Anders, 1985-
(författare)
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Busy doing nothing : Why politicians implement inefficient policies
- 2019
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Ingår i: Constitutional Political Economy. - : Springer. - 1043-4062 .- 1572-9966. ; 30:3, s. 282-299
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Tidskriftsartikel (refereegranskat)abstract
- A substantial body of literature suggests that politicians are blocked from implementing efficient reforms that solve substantial problems because of special interest groups or budget constraints. Despite the existing mechanisms that block potentially efficient reforms, real-world data show that a large number of new programs and policies are implemented every year in developed countries. These policies are often selective and considered to be fairly inefficient by ex post evaluation, and they tend to be small in size and scope. With this background, this paper studies the reasons why a rational politician would implement an inefficient public policy that is intended to obfuscate the difficulties in achieving reforms. The paper uses a simple competence signaling model that suggests that if an effective reform is impossible, engaging in strategic obfuscation through an inefficient program increases the probability of winning a re-election compared to doing nothing at all. This is because an inefficient reform does not lead voters to believe that the politician is incompetent, which a lack of action risks doing. Intentional inefficiency aiming to obfuscate the difficulty of efficient reforms can therefore complement the previous theories’ explanations of political failure.
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| 8. |
- Gustafsson, Anders, 1985-, et al.
(författare)
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Does the countryside lack cash (funding)? The impact of public bank loans on firm growth and its dependence on location
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We investigate whether public policies that aim to reduce credit constraints for small and medium-sized enterprises (SMEs) have different impacts on firms located in different types of regions. Using loan data from the state-owned Swedish bank Almi and combining coarsened exact matching with difference-in-difference regressions, we find positive but heterogeneous effects of loans on firm growth. Firms in urban regions are found to be less credit-constrained compared to firms located in other regions. However, the impact from receiving a public loan on firm growth is stronger for SMEs residing in major cities compared to firms in other regions. These results have important implications, suggesting that an evaluation of policies that are targeted to reduce credit constraints should take firm location into account.
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| 9. |
- Gustafsson, Anders, 1985-
(författare)
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Industrial policy : Political considerations, payoffs, and peculiar incentives
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of four independent papers. They deal with some aspects of industrial policy, namely public supports to firms that are intended to support innovation and growth at the firm level, using Swedish data. Two papers study the efficiency of current Swedish policies by estimating the effects of subsidies and public loans to firms, respectively.The results on subsidized firms suggests that there are some positive effects on profits and productivity, but these diminish and disappear over time. The results of public loans are more positive with long lasting effects on productivity and sales but only for smaller firms. Public loans do not lead to an increase in the number of employees in the firms that receive them.The third paper studies the selection of firms for subsidies and the incentives firms have to seek them. By modeling the decision to seek subsidies as a trade off between producing in the market and seeking grants, the results suggest that firms with low market productivity might self-select into seeking grants. The empirical results are in line with the theoretical predictions.The final paper studies the incentives that politicians have to implement programs and policies that they know will be inefficient. Since a lack of political action can make the politicians look incompetent, incumbentens have incentives to implement policies even though they know that these will be ineffective, to signal competence towards the voters.
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| 10. |
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