NEW NETWORK DESIGN STANDARDS FOR THE GRID CONNECTION OF LARGE CONCENTRATIONS OF DISTRIBUTED GENERATION

ABSTRACT Connecting large concentrations of Distributed Generation to the distribution networks usually requires high investments in network extension. This contribution describes how Enexis used its Risk Based Asset Management approach to develop new network design standards for the grid connection of large concentrations of DG in a cost-effective way

Practice-Oriented Optimization of Distribution Network Planning Using Metaheuristic Algorithms

Distribution network operators require more advanced planning tools to deal with the challenges of future network planning. An appropriate planning and optimization tool can identify which option for network extension should be selected from available alternatives. However, many optimization approaches described in the literature are quite theoretical and do not yield results that are practically relevant and feasible. In this paper, a distribution network planning approach is proposed which meets requirements originating from network planning practice to guarantee realistic outcomes. This approach uses a state-of-the-art evolutionary algorithm: Gene-pool Optimal Mixing Evolutionary Algorithm. The performance of this algorithm, as well as the proposed model, is demonstrated using a real-world case study

Short-circuit current of wind turbines with doubly fed induction generator

The short-circuit current contribution of wind turbines has not received much attention so far. This paper considers the short-circuit behavior, especially the short-circuit current of wind turbines with a doubly fed induction generator. Mostly, these wind turbines have a crowbar to protect the power electronic converter that is connected to the rotor windings of the induction generator. First, the maximum value of the short-circuit current of a conventional induction machine is determined. The differences between a crowbar-protected doubly fed induction generator and a conventional induction generator are highlighted and approximate equations for the maximum short-circuit current of a doubly fed induction generator are determined. The values obtained in this way are compared to the values obtained from time domain simulations. The differences are less then 15

Ridethrough of wind turbines with doubly-fed induction generator during a voltage dip

In this paper, a solution is described that makes it possible for wind turbines using doubly-fed induction generators to stay connected to the grid during grid faults. The key of the solution is to limit the high current in the rotor in order to protect the converter and to provide a bypass for this current via a set of resistors that are connected to the rotor windings. With these resistors, it is possible to ride through grid faults without disconnecting the turbine from the grid. Because the generator and converter stay connected, the synchronism of operation remains established during and after the fault and normal operation can be continued immediately after the fault has been cleared. An additional feature is that reactive power can be supplied to the grid during long dips in order to facilitate voltage restoration. A control strategy has been developed that takes care of the transition back to normal operation. Without special control action, large transients would occur

Comparing probabilistic load flow methods in dealing with uncertainties at TSO/DSO interface

Increasing decentralized and renewable power production, which is mainly installed in distribution networks, makes planning of the transmission network more challenging. The application of probabilistic power flow methods provides additional information that can be used to predict future power flows in networks with a high share of decentralized and renewable generation. This paper compares numerical and analytical probabilistic power flow approaches focusing on the trade-off between computational time and information gain. It is shown that for the 6-bus Roy Billinton Test System, using normally distributed random variables, the analytical method is a suitable alternative to the numerical method. Reducing computational effort while retaining considerable accuracy. This makes analytical probabilistic power flow an interesting method for studying networks with a high share of decentralized and renewable generation

Snellere transitie door voorspellen duurzame energie

De energietransitie wint steeds meer aan snelheid. Het wordt daarom steeds belangrijker in te schatten in welk tempo en op welke locaties de consequenties van de energietransitie zich gaan manifesteren. Met behulp van statistische analyses kunnen de gevolgen van de verduurzaming van het energiesysteem locatiespecifiek worden voorspeld. Dat maakt het voor netbeheerders en gemeenten mogelijk om hierop tijdig in te spelen. Bijvoorbeeld door het elektriciteitsnet te verzwaren of voldoende oplaadpunten voor elektrische auto’s te plaatsen.\u3cbr/\u3

Statistical methods for condition assessment of low-failure assets

\u3cp\u3eFor (electrical) infrastructure assets a high reliability is required. When assets cannot be monitored and no condition information is available, statistical methods can be used to assess their condition. This paper discusses statistical methods to assess the condition of LV cables, which is a typical example of electric components with a very low failure rate. Two survival methods and three classification methods are compared. The Cox Proportional Hazard model proved to be the most suitable. The influence of variables on the failure probability provides insight in failure mechanisms and asset groups which have a high failure probability. In this paper it is proved that a great amount of information can be gained using survival analysis for ageing infrastructure assets.\u3c/p\u3

Voltage dip ride-through control of direct-drive wind turbines

With an increasing amount of wind energy installed, the behaviour of wind turbines during grid disturbances becomes more important. Grid operators require that wind turbines stay connected to the grid during voltage dips. This contribution presents a controller that can be used to keep direct-drive wind turbines with permanent magnet generator connected to the grid during voltage disturbances. The behaviour of the wind turbine during a grid faults is demonstrated by simulations