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In recent times renewable energy sources have become an integral part of the modern power grid. As a result, the overall system inertia of the grid has been reduced, thus leading to frequency instability issues such as fast rate of change of frequency. Thus, to compensate for the declining inertia, it is important to carefully select renewable ener...
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However, it is important to...
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Citations
... The efficient integration of new energy power generation and a modern power grid is the core of the world's sustainable energy transformation, attracting more and more attention [1,2]. So far, various new power systems have been developed successively [3]. ...
... (5) Lack of transparent and effective monitoring mechanisms for REIPPPP: There are no sufficient effective monitoring agencies to monitor RE development through the REIPPPP program and ensure all timelines and RE targets are met. (6) Lack of indigenous manufacturing companies: There is the lack of sufficient indigenous manufacturing companies for RE-generating units in South Africa, as the sector is heavily dependent on imported technologies.(7)Uncertainties of RE resources: The power delivery of RE generators is heavily dependent on weather conditions[6],[67],[68]. Poor solar irradiance during the winter season and poor wind speed during cloudy days limit the Renewable energy market bureaucratic: Delays in the signing of power purchase agreements (PPAs) for awarded auction projects hinder the timely development of new RE capacity[70]. ...
... For example, to optimize the rate of change of frequency (ROCOF) and system frequency deviation, the study in [28] assessed frequency dynamics and proposed a novel technique for sizing and deploying the BESS-VSG units in microgrids. The study in [29] constructed a Mixedinteger Non-linear Programming based optimization model of RES and BESS-VSG unit placement by considering the low inertia challenge in renewable-integrated microgrids. The objective function was designed to optimize the system's inertia while minimizing the operating and investment expenses of the microgrid system components. ...
Optimum design for microgrids that include renewable energy sources (RESs) is a complex process that requires optimization across a wide range of factors, including economic, technological, and environmental effectiveness. The inverter-connected RES units lack the rotational mass required to maintain the system's inertia and can result in significant frequency instability during disturbances. The battery energy storage system-based virtual synchronous generator (BESS-VSG) is a unique approach to address this challenge since it mimics a conventional synchronous generator (SG) using the inverter regulation concept. Furthermore, given the recent rise in electric vehicles (EVs), EV owners' charging patterns impact the microgrid's operational, financial, and technological aspects. Therefore, this research offers a novel Modified Multi-objective Salp Swarm Optimization Algorithm (MMOSSA)-based technique for optimal photovoltaic (PV), wind turbine (WT), BESS-VSG, and EV charging station (EVCS) allocation on microgrids. The objective function is designed to optimize the total net present cost (TNPC), levelized cost of electricity (LCOE), energy loss, frequency deviation, voltage stability indicator (), and carbon emissions. The proposed strategy is evaluated on two real-world grid networks: Masirah Island in Oman and Ankara in Turkey, where wind prospects, solar potential, and EV charging patterns are conflicting. This study investigated PV/BESS-VSG, WT/BESS-VSG, and PV/WT/BESS-VSG configurations regarding the weather and load variability for the two test networks. The obtained results demonstrate that the PV/WT/BESS-VSG is the best choice for both the test networks, with TNPC values of 261030.9 $ and 303840.5 $, respectively, and LCOE values of 0.0383 $/kWh and 0.0469 $/kWh, respectively. The carbon emissions are reduced by 88.8% and 87.3% for the two test networks, respectively. In addition, with the accurate PV/WT/VSG design and appropriate EVCS placements, the microgrids' renewable fraction, the quantity of sold energy, and technical characteristics improved significantly. Moreover, employing numerical analysis, different loss of power supply probability (LPSP) values, spacing index, and hyper-volume index, the suggested MMOSSA method is compared to five relevant multi-objective optimization strategies. The findings demonstrate that the MMOSSA Pareto fronts offer better solutions across all the assessments.
... The authors in [20] propose a system-wide inertial frequency response using a strategically placed phasor measurement unit (PMU). Compared with the conventional model, the author claims that the inertia of the developed model is higher [21]. A decoupling scheme can be applied by converter voltage amplitude to adjust the active power independently [22]. ...
... Equations (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) control the frequency input and the active power control for the limiters. The additional support for the frequency stability is by inertial support and a BESS. ...
Energy access, climate change and public health issues are some major drivers for the need for renewable sources. However, most renewable sources, excluding large hydro, have zero or negligible rotational inertia, which is critical to stabilizing the power system after contingency. Therefore, this paper proposes a droop-based inertia emulator to reduce the rate of change of frequency and frequency deviations. The robustness of the controller is analysed by applying various uncertainties and disturbances of power system components that were carried out using DIgSILENT PowerFactory simulations. The obtained results are compared with existing literature and the desired performance shows an improvement in the rate of change of frequency of 34.78% for an IEEE 6-bus system, 24.32% for a 12-bus system and 18% for a 39-bus system.
... Hence, in this sub-section, the maximization of the system inertia is given as one of the problem objectives. The objective function is expressed as in Eq. (1) [22]. ...
... Equations (16,17,18,19,20,21,22) govern the operation of all existing and prospective RE power generators [18]. Equation (16) specifies the generating power limit for existing thermal generators. ...
... Equation (20) gives the binary investment decision that choses between wind turbine and solar PV plant for installation at a bus, thus preventing investment in both RE technologies at the same time. Equations () - (22) limits the maximum number of wind turbine, and solar PV plants that can be installed during the 21planning horizon, respectively. ...
The need for a cleaner environment with lesser fossil fuel-fred generators has
increased the call for higher share of renewable energy generators (REGs) in the
grid. To achieve this, various economic incentive schemes have now been intro�duced by the government to speed up investment in renewable energy technologies.
However, it is important to also consider the stability of the grid even as more REGs
are being integrated. To this end, this paper proposes a novel feed-in tarif (FiT) and
inertia integrated generation and transmission expansion planning (GTEP) optimiza�tion model, which maximizes the FiT incentive scheme and the overall system iner�tia, while minimizing cost and CO2 emissions. The proposed model is then imple�mented on an IEEE 6-bus system and solved using CPLEX solver in GAMS under
three study cases. The model simulation result obtained reveals that the introduction
of FiT into the GTEP model reduces the overall system cost by 11.9% (599 M$ to
526 M$), while the integration of system inertia into the GTEP model increases the
overall system inertia by 8% (5.680 s to 6.139 s). In addition, sensitivity analysis
results reveal that as the penetration of REGs into the grid increases, the total system
cost, and FiT received also increase, however, the fraction of FiT payment received
relative to the total investment cost decreases after 50% REGs penetration level for
the same FiT rate. Finally, comparing the model results with other soft computing
optimization techniques showed its superiority in terms of speedy convergence and
computation time.
... With increasing awareness of the negative effect of fossil fuel, countries around the world are trying to cut greenhouse gas emissions in line with renewable energy (RE) policies such as the Paris agreement [1][2][3][4]. Measures which will help promote renewable energy generators (REGs) integration to grid, and discourage the use of fossil fuel fired generators are now been enforced [5]. ...
As the power grid transforms towards a renewable energy dominant grid, which are associated with frequency stability challenges, it is important to combat these challenges through proper power system planning. This paper therefore investigates the impact of hybrid energy storage (HES) in enhancing the frequency stability of the modern grid. The optimization problem is formulated as a mixed integer quadratic constrained programming model to minimize the system cost, while maximizing system inertia. The proposed model is then implemented on an IEEE 6-bus system, and solved using CPLEX solver in GAMS, with its performance evaluated using two study cases. Case 1 considers only the economic objective (cost), while case 2 considers both the economic objective (cost) and the technical objective (system inertia). The result show that the incorporation of HES in the generation planning model improved the overall system inertia of the system by 11% (from 6.199s in case 1, to 6.901s in case 2), however the total system cost increased by 3% (from 218M$ in case 1 to 2.25M$ in case 2).
... Inertia Constraint. As more conventional generators are being replaced with renewable energy generators and energy storage systems, it is important to ensure that the equivalent kinetic energy of the decommissioned synchronous generators can be provided by the inertia energy of energy storage units in order to maintain the system's frequency stability [29,30]. During times of contingency, the released kinetic energy from synchronous generators and energy storage units will help the system regain stability and significantly reduce the effect of the transient event [20,23]. ...
In recent times, the power grid composition is changing as more renewable energy generators and energy storage systems are being integrated. This in turn influences the dynamics of the new grid as frequency instability sets in due to declining system inertia. It is therefore important to properly select renewable energy generators and energy storage units to mitigate frequency instabilities, particularly during times of system contingencies. This study therefore, proposes a new deterministic generation and transmission expansion planning model that enhances the frequency stability of the modern grid. Thus, a mixed integer quadratic constrained programming model is developed to minimize emissions, and cost, while maximizing the overall system inertia. The proposed multi-objective model was validated using three case scenarios and tested on a modified IEEE 9-bus test system. The results obtained from the model simulation reveal that the proposed model (case 3) achieves better frequency stability, higher system inertia, and minimized emissions compared to the models in case 1(only economic objective is considered) and case 2(only economic and environmental objectives are considered), however, at a marginally higher cost which justifies the aim of the study.
