Wl Wil Kling

Impacts of Wind Power on Thermal Generation Unit Commitment and Dispatch

This paper proposes a new simulation method that can fully assess the impacts of large-scale wind power on system operations from cost, reliability, and environmental perspectives. The method uses a time series of observed and predicted 15-min average wind speeds at foreseen onshore- and offshore-wind farm locations. A Unit Commitment and Economic Dispatch (UC-ED) tool is adapted to allow for frequent revisions of conventional generation unit schedules, using information on current wind energy output and forecasts for the next 36 h. This is deemed the most faithful way of simulating actual operations and short-term planning activities for a system with large wind power penetration. The problem formulation includes ramp-rate constraints for generation schedules and for reserve activation, and minimum up-time and down-time of conventional units. Results are shown for a realistic future scenario of the Dutch power system. It is shown that problems such as insufficient regulating and reserve power-which are typically associated with the variability and limited predictability of wind power-can only be assessed in conjunction with the specifics of the conventional generation system that wind power is integrated into. For the thermal system with a large share of combined heat and power (CHP) investigated here, wind power forecasting does not provide significant benefits for optimal unit commitment and dispatch. Minimum load problems do occur, which result in wasted wind in amounts increasing with the wind power installed

HVDC Connection of Offshore Wind Farms to the Transmission System

This paper presents a technical and economic analysis to evaluate the benefits and drawbacks of grid connecting offshore wind farms through a dc link. A first case, concerning a 100-MW wind farm, is thoroughly investigated and cases of larger wind farms (200 and 500 MW) are presented. Three different transmission solutions are compared: 150-kV ac, 400-kV ac, and high-voltage dc based on voltage sourced converters (VSC-HVDC). After a brief overview of the features of these connection solutions, the related operational aspects are evaluated. An economic assessment compares the dc connection option to the ac alternatives, taking into account the investment, operation, and maintenance costs, and the negative valorization of losses and energy not supplied. Economic assessment includes sensitivity analyses of parameters, which could impact the 100-MW wind farm: distance, component costs, dc converter reliability, and dc converter losses

Integration Issues of Distributed Generation in Distribution Grids

In todays distribution grids the number of distributed generation (DG) units is increasing rapidly. Combined heat and power (CHP) plants and wind turbines are most often installed. Integration of these DG units into the distribution grid leads to planning as well as operational challenges. Based on the experience of a Dutch distribution system operators (DSO), this paper addresses several possibilities to handle grid planning issues. Effects on voltage control, grid protection, and fault levels are investigated and described. These aspects are illustrated with the aid of simulations on an existing distribution grid. It is demonstrated that in compact distribution grids voltage control problems and blinding of protection are not likely to occur and that false tripping and fault level have to be considered carefully.

Virtual power plants: An answer to increasing distributed generation

In the future an adaptive power system is required to integrate the emerging distributed generation (DG) and renewable energy sources (RES). Since most present power systems are based on active controlled transmission network and passive distribution network, the development of smart grids in the distribution network will facilitate and enhance the growth of DG&RES. To develop smart grids, active control of both distribution network and DG&RES is needed. This research employs the virtual power plant (VPP) concept to develop active control of the present and emerging DG&RES. This paper discusses the impact of DG&RES and highlights the advantages of the VPP concept taking major technical, economical and regulatory aspects in consideration.

Distributed routing algorithms to manage power flow in agent-based active distribution network

The current transition from passive to active electric distribution networks comes with problems and challenges on bi-directional power flow in the network and the uncertainty in the forecast of power generation from grid-connected renewable and distributed energy sources. The power flow management would need to be distributed, flexible, and intelligent in order to cope with these challenges. Considering the optimal power flow (OPF) problem as a minimum cost flow represented with the graph, this paper applies a cost-scaling push-relabel algorithm in order to solve the OPF in a distributed agent environment. The algorithms performance is compared with the successive shortest path algorithm developed in our previous work. The simulation is implemented for both meshed and radial networks. The simulation results show the advantages of the cost-scaling push-relabel algorithm over the shortest path algorithm in the radial networks with respect to significantly reduced number of exchanged messages on the agent platform, and thus the reduced time for calculation. This will be of great importance if the method is to be applied to a large system.

A Game Theory Strategy to Integrate Distributed Agent-Based Functions in Smart Grids

The increasing incorporation of renewable energy sources and the emergence of new forms and patterns of electricity consumption are contributing to the upsurge in the complexity of power grids. A bottom-up-agent-based approach is able to handle the new environment, such that the system reliability can be maintained and costs reduced. However, this approach leads to possible conflicting interests between maintaining secure grid operation and the market requirements. This paper proposes a strategy to solve the conflicting interests in order to achieve overall optimal performance in the electricity supply system. The method is based on a cooperative game theory to optimally allocate resources from all (local) actors, i.e., network operators, active producers, and consumers. Via this approach, agent-based functions, for facilitating both network services and energy markets, can be integrated and coordinated. Simulations are performed to verify the proposed concept on a medium voltage 30-bus test network. Results show the effectiveness of the approach in optimally harmonizing functions of power routing and matching.

Smart Power Router: A Flexible Agent-Based Converter Interface in Active Distribution Networks

Due to the large-scale implementation of distributed generation, the power delivery system is changing gradually from a “vertically” to a “horizontally” controlled and operated structure. This transition has prompted the emergence of the active distribution network (ADN) concept as an efficient and flexible distribution system to deal with various challenging issues. This paper addresses a multiagent system (MAS) as a suitable technology to manage autonomous control actions and perform the coordination in an ADN. In this agent-based ADN a smart power router is implemented, which can flexibly integrate network areas and optimally manage power flows. Operational and control functions of the power router has been investigated in a laboratory experiment. In this lab setup, a configuration of the power router is established in a combination of a three-inverter system and an agent. The experiments show that the ADN can operate in an efficient and flexible way with the support of the power router interface. The control function of the inverters and the operation of MAS are thoroughly verified.

Power quality aspects of a future micro grid

Due to the increase of distributed generators (DG) in the public grid some parts, with high penetration of DGs, could be transformed into an autonomously operating micro grid. This paper will show how the grid of an existing Holyday park can be changed into an autonomous micro grid. An additional control system as well as additional storage systems and power electronics have to be implemented in order to maintain the balance between load and generated power, and to guarantee the quality of supply on an acceptable level. Therefore a measurement program is running concerning the generated power and the load behavior and some aspects of the quality of supply. This paper is especially focused on the existing harmonic problem coming from the interaction between grid components and installed solar inverters. At the end a new power quality test laboratory is presented

Pseudo dynamic transitional modeling of building heating energy demand using artificial neural network

This paper presents the building heating demand prediction model with occupancy profile and operational heating power level characteristics in short time horizon (a couple of days) using artificial neural network. In addition, novel pseudo dynamic transitional model is introduced, which consider time dependent attributes of operational power level characteristics and its effect in the overall model performance is outlined. Pseudo dynamic model is applied to a case study of French Institution building and compared its results with static and other pseudo dynamic neural network models. The results show the coefficients of correlation in static and pseudo dynamic neural network model of 0.82 and 0.89 (with energy consumption error of 0.02%) during the learning phase, and 0.61 and 0.85 during the prediction phase, respectively. Further, orthogonal array design is applied to the pseudo dynamic model to check the schedule of occupancy profile and operational heating power level characteristics. The results show the new schedule and provide the robust design for pseudo dynamic model. Due to prediction in short time horizon, it finds application for Energy Services Company (ESCOs) to manage the heating load for dynamic control of heat production system.

Theft detection and smart metering practices and expectations in the Netherlands

This paper provides insight into the illegal use or abstraction of electricity in the Netherlands. The importance and the economic aspects of theft detection are presented and the current practices and experiences are discussed. The paper also proposes a novel methodology for automated detection of illegal utilization of electricity in the future distribution networks equipped with smart metering infrastructure. The necessary data requirements for smart meters and distribution substations are defined, in order to unlock this feature in distribution network. The paper also proposes the measures, which should be undertaken by the smart metering standards.