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In this paper, the input signals and the control model structure of the HVDC link POD control are studied. First, a benchmark is proposed to investigate the input signal selection of the POD controller. Next, by considering different situations, it is shown, based on the residues criteria, that the choice of the input signal depends on the parameters of the system. More precisely, the numerical results...
Low Voltage Direct Current (LVDC) distribution systems potentially enable more efficient power distribution and wider uptake of distributed renewables and energy storage. They do however present significant fault protection and safety challenges. To address these, the use of advanced protection techniques or significant system redesign is required. This paper reviews these protection key challenges,...
The present paper proposes a method for enhancing the resilience of distribution systems that are exposed frequently to disastrous conditions. In case of a fault, the distribution system is sectionalized into self-sufficient microgrids in order to prevent a possible spread of the fault with the minimum load shedding of the islanded portion of the distribution system. The design of self-sufficient...
The analysis and validation of innovative methods and concepts for distribution grids like smart grid approaches require a realistic representation of the grid structure. However, the availability of real grid data for distribution grids is insufficient. Therefore, a method for the generation of model grids for all distribution grid voltage levels is developed, utilizing publicly available map data...
The increasingly introduction of Photovoltaic (PV) systems into residential power system because of customers' desire to reduce electricity supply cost causes detrimental impacts, e.g. voltage operation and voltage unbalance (VU) issues. In order to cope with these problems, the control strategy of PV units where both reactive power control and active power curtailment are allowed has been proposed...
This work presents a linear solution for the short-term hydro-thermal scheduling problem linked to long-term conditions through a piecewise-linear Future Cost Function (FCF). Given end-point conditions to conform long-term water releases, and given actual reservoir conditions, a segment of a pre-built piecewise future cost function will be chosen. The linear characteristic of the FCF segment will...
In this paper, a mathematical approach for the optimal planning of integrated energy systems is proposed. In order to address the challenges of future, RES-dominated energy systems, the model deliberates between the expansion of traditional energy infrastructures, the integration of these infrastructures using conversion technologies (e.g. gas-to-electricity-and-heat, power-to-heat, power-to-gas),...
The Modular Multilevel Converter (MMC), being a complex system, requires a number of controllers to function properly. These range from low level switching pattern generation to high level control loops. Among these controllers are modulation techniques that calculate the insertion indices, control inputs that decide the number of sub-modules inserted in a given arm. One such technique is compensated...
In this paper we elaborate on how a hydropower producer's expected marginal value of water (water value) is affected when considering both sales of energy and reserve capacity in a liberalized market setting. We derive analytical expressions for the water value in this market context, and verify these through numerical computations. We find that the water values are more sensitive to changes in the...
With the advent of smart grids and the higher level of requirement for the quality of supply, restoration of distribution networks is a timely topic that deserves to be revisited. In this paper, the concept of multi-agent automation in smart grids is applied to build a self-healing framework to be used for the restoration service. The optimal restoration solution is found solving a global optimization...
A Distribution System Operator (DSO) might consider a capacity contract as a planning alternative to defer grid investments. A Virtual Power Plant (VPP) might be able to provide such capacity and change its production as requested by the DSO. This article presents an assessment of the impact of this type of distribution capacity contract (DCC) on VPP's remuneration. This assessment is done by comparing...
The economic impact of forecasting errors in the residual demand curves of the secondary regulation reserve market is analysed in the context of the operation of a closed-loop and daily-cycle pumped-storage hydropower plant. The plant participates in the day-ahead energy market as a price-taker and in the secondary regulation reserve market as a price-maker. The secondary regulation energy due to...
Due to growing uncertainties in the grid, probabilistic load flow methods achieve more attention. The Point Estimate Method (PEM) was introduced in 1975 first and was enhanced since then. In a first step, this paper evaluates the applicability of the method considering different input data to analyze the limitations of the method. Different input data exist through the diversity of generators and...
The paper aims to determine the day-ahead market bidding strategies for retailers with flexible demands to maximize the short-term profit. It proposes a short-term planning framework to forecast the load under dynamic tariffs and construct biding curves. Stochastic programming is applied to manage the uncertainties of spot price, regulating price, consumption behaviors and responsiveness to dynamic...
Primary frequency control is often added to the control system of a high-voltage DC (HVDC) transmission that interconnects two nonsynchronous ac grids. As the active-power actuation lag is typically in the range of hundreds of milliseconds, the HVDC primary frequency control can be made fast enough to permit inertia sharing among the interconnected ac grids. This reduces the maximum frequency fall...
This contribution deals with the determination of the capacity of grid connection points in order to connect potentially more e.g. wind energy converters (WEC) to the grid. At first the determination of the short-circuit power at the fundamental frequency is outlined. Then the frequency characteristic of the grid impedance is analyzed. The focus lies on the identification of the grid impedance by...
This paper addresses the challenges associated with the operation of a distribution system with high penetration of wind power. The paper presents some preliminary investigations of an ongoing Danish research work, which has as main objective to reduce the network losses by optimizing the reactive power flow in 60kV distribution networks through controlling the ability of wind power plants (WPPs)...
This paper proposes the use of structural equation modelling (SEM) to assess the contributions of on-load tap changer (OLTC) on voltage controlled demand response (VCDR) in future power systems. For the development of a VCDR scheme, optimal deployment of the available resources is necessary. Thus, understanding the contributions of voltage controlled devices such as OLTCs to VCDR will assist the optimal...
The increased integration of PV systems in the low voltage network causes many problems in network operations. The EU project STORY is tackling these problems with adding energy storage to the grid. In this paper we present new control concept with peak demand control algorithm which is used on storage unit in LV distribution network. The algorithm development is based on real measurements from transformer...
This paper proposes a convex model for the optimal service restoration of power distribution networks after a permanent fault. The proposed method minimizes the out of service area providing the minimum switching actions and the tap position of the on load tap changer (OLTC) placed at the HV/MV substations subject to voltage and capacity limits of the distribution network. The nonlinear constraints...
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