Large-scale Integration Of Renewable Energy Sources Research Articles

Harmonics Constrained Approach to Composite Power System Expansion Planning with Large-Scale Renewable Energy Sources

Renewable energy sources (RES) are becoming more attractive due to the global demand for the utilization of clean energy and their easy accessibility. The integration of renewable energy technologies into power systems has been made easy, such that RES can be incorporated into small distribution systems or power grids. This integration of RES has negative impacts on power quality, system reliability, and network security. This could affect the RES performance and causes power quality-related problems such as harmonics, voltage flickers, swell, and sag. This paper presents a generation and transmission expansion planning model with the integration of large-scale RES considering harmonic emissions constraints. This method uses a weighted sum approach to combine the multi-objective optimization problems, thereby minimizing the total costs, active power loss, and harmonic power loss. An analytical technique was developed to estimate and quantify the harmonic emissions from the RES components. The proposed AC mixed-integer non-linear optimization problem was solved using algebraic modeling language. The proposed model is demonstrated on non-distorted Garver’s test bus system and 48-bus of Nigeria’s power system. The results obtained from the sensitivity analysis can be used as a decision-making tool to determine the best approach to minimize harmonic emissions from RES integration into the grid.

Voltage control and virtual synchronous generator control of HVDC interconnection line for improving stability of power system including large‐scale wind farm

Large-scale integration of renewable energy sources (RESs) such as wind power can impact on the existing power system's stability. For example, there is a possibility that the wind farm (WF) cannot be maintained stable and then it is disconnected from the grid when the instantaneous voltage sag caused by a grid disturbance occurs. Moreover, the increasing integration of RESs in the power system can reduce the number of conventional synchronous generators (SGs) connected to the grid, and lead to a reduction of system inertia in the grid. The system inertia reduction can cause larger and faster frequency fluctuations during the transient period. Hence, this paper proposes a new control strategy composed of the voltage control for suppressing the voltage sag and the virtual synchronous generator (VSG) control based on the proportional-integral-differential (PID) fuzzy logic control (FLC) for maintaining the frequency stability which is performed by high voltage direct current (HVDC) interconnection line. The aim of the new control strategy is to improve the stability of the entire power system with large-scale integration of RESs. The effectiveness of the proposed strategy is confirmed through the simulation analyses by PSCAD/EMTDC.

Reliability assessment of composite generation and transmission expansion planning incorporating renewable energy sources

Modern power system exploitation of large-scale Renewable Energy Sources (RESs) is prevalent due to the RES effect of reducing the heavy dependence on fossil fuels and the resultant power quality improvement. Therefore, this paper investigates the reliability assessment of a power system with integration of large-scale RESs with emphasis on their impacts on the expansion planning procedure. A multi-state Markov model is proposed to analyze the availability and reliability of the stochastic nature of RESs and High Voltage Direct Current transmission links. A Mixed Integer Nonlinear Programming model is developed to minimize the total investment and operation cost of the generating units and the cost associated with power outage as well as improving power system reliability. An Outer Approximation Algorithm, a powerful solver embedded in the Advanced Interactive Multidimensional Modeling System, was employed in solving the proposed model and implemented using the IEEE 6- and 24-bus Roy Billinton Test System to demonstrate its effectiveness. The results obtained from the simulation reveal that the proposed model performance achieves effective reliability and an enhanced voltage profile.

Large scale integration of intermittent renewable energy sources in the Greek power sector

As a member of the European Union, Greece has committed to achieve ambitious targets for the penetration of renewable energy sources (RES) in gross electricity consumption by 2020. Large scale integration of RES requires a suitable mixture of compatible generation units, in order to deal with the intermittency of wind velocity and solar irradiation. The scope of this paper is to examine the impact of large scale integration of intermittent energy sources, required to meet the 2020 RES target, on the generation expansion plan, the fuel mix and the spinning reserve requirements of the Greek electricity system. We perform hourly simulation of the intermittent RES generation to estimate residual load curves on a monthly basis, which are then inputted in a WASP-IV model of the Greek power system. We find that the decarbonisation effort, with the rapid entry of RES and the abolishment of the grandfathering of CO2 allowances, will radically transform the Greek electricity sector over the next 10 years, which has wide-reaching policy implications.

Impact of CO 2 reduction policies on the development of renewable energy sources

The paper examines the impact of CO 2 reduction policies on the strategic planning of the energy sector. Attention is paid to the conflicts between economic and environmental goals influencing the penetration of renewable energy sources (RES). A linear programming (LP) model is applied to represent the structure of the Greek energy system. Energy flows are optimized with respect to the system's economic efficiency. The model incorporates a constraint concerning the CO 2 emissions generated from the various energy production and consumption activities. The results show that a substantial reduction of CO 2 emissions can be achieved through a large scale integration of RES into the energy system. Shadow prices identified by the model denote the real cost for the economy of using alternative energy forms under various environmental restrictions. They are useful to indicate the changes in the prevailing pricing mechanisms that are necessary to direct the market forces towards the desired policy goals.