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Wind energy conversion systems (WECSs) have a history in the power generation industry and have become increasingly popular in the recent years. As all the other forms of power generation, it is important that these sources are reliable and resilient with the ability to sustain harsh electrical system conditions. Part of this resilience comes in the form of effective electrical protection systems,...
This paper studies the inclusion of averaged VSC-based grid interfaces and HVDC networks into stability type simulations, and compares the accuracy and speed of three multi-terminal DC dynamic models: 1) a state-space based model, 2) a multi-rate improved model, and 3) a reduced-order model. The accuracy comparison is conducted by qualitative time-domain analysis taking the state-space model as a...
In Germany, the absorption capacity of distributed generation (DG) in rural and suburban low voltage (LV) networks is currently restricted due to possible over-voltages above the limit set by the voltage standard. Whilst the thermal limits can only be solved by storage, curtailment or network extension, a number of advanced and relatively affordable technologies can be implemented to maintain the...
The disjoint feasible zones make the economic dispatch problem non-convex. The existed solving schemes either rely on random searching, or use additional auxiliary variables, or involve high nonlinearity. In this paper, a new method is presented to overcome the main drawbacks in existed schemes. Due to its simple structure, the proposed approach also has the advantage to expedite the implementation.
This paper investigates various factors influencing the capability of MMC-VSC-HVDC systems to enhance damping of system oscillations. The investigation is done in the frequency-domain using a detail model of a MMC-VSC-HVDC system. Simulation results demonstrating the controllability of MMC-VSC-HVDC systems on inter-area and local oscillations in interconnected power systems are described. It is revealed...
This paper proposes a continuous time Markov chain (CTMC) based sequential analytical approach for composite generation and transmission systems reliability assessment. The basic idea is to construct a CTMC model for the composite system. Based on this model, sequential analyses are performed. Various kinds of reliability indices can be obtained, including expectation, variance, frequency, duration...
If the overload branch is tripped, the power flow will transfer to other branches in corresponding transmission section. Therefore, fast prediction of cascading overload is of great significance for transmission section security protection. This paper proposes an algorithm combined with DC sensitivity and compensation method after the traditional study of branch outage. Based on DC power flow model,...
Recent developments in the advanced control of renewable energy resources and distributed generation systems are resulting in pressures to adopt tariffs of increasing complexity. Independently of the tariff structure, utility customers can programmatically optimize their schedule consumption for reducing their energy bills. However, as the penetration of distributed energy resources increases, there...
This paper presents an enhanced control scheme for an interior permanent magnet (IPM) synchronous generator based direct drive wind turbine, incorporating maximum torque per ampere trajectory (MTPA) and maximum power extraction (MPE) algorithm. The main advantage of incorporating MTPA trajectory in the control scheme is that it can generate the required torque with a minimum stator current to minimize...
With large amount of renewable energy resources integrated into strong coupling interconnected power system (IPS), the conventional automatic generation control (AGC) scheme leads to the increase of the AGC regulation cost and the shortage of the AGC regulation amount in some control areas. In this paper, cooperation of AGC in different control areas was used to solve these problems. Optimal cooperation...
In order to improve the economic benefit of AC / DC hybrid microgrid, an optimal operation under spot price method is proposed. Firstly, an expectation programming model is constructed considering the spot price as the control variable; Secondly, based on day-ahead dispatch, considering the WT and PV power forecasting error, an real-time adjustment strategy is presented, which considers the real-time...
An algorithm for the detection and frequency estimation of periodic forced oscillations in power systems is proposed. The method operates by comparing the periodogram of synchrophasor measurements to a detection threshold. This threshold is established by deriving a general expression for the distribution of the periodogram and is related to the algorithm's probabilities of false alarm and detection...
Solar storms can affect the terrestrial power grid by inducing potential differences between points on the earth. These can couple into the power system through earthed structures such as transformer earths, which in turn can result in transformer saturation through geomagnetically induced current (GIC). For systems such as voltage-source converter (VSC) HVDC, this causes a variety of problems. This...
The integration of distributed renewable energy sources (RES) and the electrification of devices raise new challenges for the distribution system operator (DSO). This paper assesses PAR versus cost tradeoff when scheduling an electric vehicle (EV) fleet. We formulate a bilevel Mixed-Integer Linear Programming optimization problem. At the lower level, we minimize individual household electricity bills...
Frequency monitoring network (FNET/GridEye), a wide-area monitoring system (WAMS) at distribution level, is known to be able to reveal many insights of power grid dynamics through the real time phasor measurement collected by frequency disturbance recorders (FDRs). A large number of FDR units are currently deployed in several power grids worldwide. This paper focuses on the inertial frequency responses...
Utility scale battery storage will soon reach a level of maturity where the modular design of the technology and aggregation will allow custom-built solutions for energy and ancillary service needs of the power system. Several projects are in the demonstration phase worldwide and hold promise for successful incorporation of battery storage into traditional power systems operations. In contrast to...
The goal of this paper is to present the efficiency and performance of a new ternary energy storage model in the competitive electricity market. Using the state-of-the-art mixed-integer progamming technique, the new energy storage model can be explicitly cast as ternary states: (−1) PUMP, (0) OFF, and (1) GEN to represent the physical energy storage constraints and desired operating parameters in...
This article is focused on the droop-based DC voltage control design for multi-terminal VSC-HVDC grid systems, considering the AC and the DC system dynamics. The droop control design relies on detailed linearized models of the complete multi-terminal grid, including the different system dynamics, such as the DC grid, the AC grid, the AC connection filters and the converter inner controllers. Based...
This paper presents a planning framework to find the minimum storage sizes (power and energy) at multiple locations in distribution networks to reduce curtailment from renewable distributed generation (DG), specifically wind farms, while managing congestion and voltages. A two-stage iterative process is adopted in this framework. The first stage uses a multi-period AC optimal power flow (OPF) across...
This paper presents a comprehensive low-voltage residential load model of price-based demand response (DR). High-resolution load models are developed by combing Monte Carlo Markov chain bottom-up demand models, hot water demand models, discrete state space representation of thermal appliances, and composite time-variant electrical load models. Price-based DR is then modeled through control algorithms...
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