IET Renewable Power Generation
Volume 13, Issue 16, 09 December 2019
Volumes & issues:
Volume 13, Issue 16
09 December 2019
-
- Source: IET Renewable Power Generation, Volume 13, Issue 16, page: 2957 –2957
- DOI: 10.1049/iet-rpg.2019.1327
- Type: Article
- + Show details - Hide details
-
p.
2957
(1)
- Author(s): Biyue Huang ; Haishun Sun ; Long Wang ; Yahao Chen ; Yuming Liu
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 2958 –2965
- DOI: 10.1049/iet-rpg.2019.0362
- Type: Article
- + Show details - Hide details
-
p.
2958
–2965
(8)
The sub-synchronous control interaction (SSCI) has frequently occurred in the direct-drive permanent magnetic synchronous generators (PMSGs) based wind farm integrated to the weak AC network. The system strength, i.e. short-circuit ratio (SCR) has been believed as the critical factor so far. However, the impedance–frequency characteristics of the practical network exhibit a strong resonance that might have impacts on the SSCI as well. In this study, considering the network resonance, the eigenvalue- and impedance-based analyses are conducted to study the SSCI phenomenon in the grid-connected PMSG system. The impacts on SSCI from system strength, network resonance and network-resonant frequency are investigated firstly. Then, the parameter limits of PMSG control for the stable region are calculated to discuss the effects of network resonance on the parameter design. The results show that the network resonance plays a critical role in the SSO mode. When the network resonance is considered in the PMSG system, the SSO would arise more easily, and the stable region of the control parameter will be reduced. Meanwhile, the frequency of the SSO mode matches well with the network resonance frequency in dq frame. The analytical results are all verified by simulation.
- Author(s): Wei Liu ; Xiaorong Xie ; Jan Shair ; Huakun Liu ; Jingbo He
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 2966 –2976
- DOI: 10.1049/iet-rpg.2019.0326
- Type: Article
- + Show details - Hide details
-
p.
2966
–2976
(11)
Recently, emerging sub-synchronous oscillation (SSO) issues caused by the interaction between power electronic converters and weak AC grids have provoked serious stability concerns. Impedance-based modelling approaches have been widely employed for stability analysis of such interactions. In this study, a sequence-domain frequency-coupled impedance model (FCIM) and the corresponding stability criterion are proposed. First, a fast identification method of the FCIM is proposed, in which the impedance-frequency curves of the FCIMs at multiple frequencies are measured, followed by identification of their transfer function models. Next, the proposed method is applied to model a practical system, where a SSO event once occurred due to the interactions between direct-drive wind turbines and a weak AC grid. The individual FCIMs of wind turbine generators, steam turbine generators and static var generator in this system are derived. After that, an aggregated FCIM is formed by combining the FCIMs without extra coordinate transformation. Then, the aggregated FCIM-based stability analysis is carried out to investigate the interaction between the wind farms and weak AC grids. In the end, the results of FCIM-based stability analysis are verified by time-domain simulations.
- Author(s): Menglin Zhang ; Lingling Le ; Jiakun Fang ; Xiaomeng Ai ; Wei Yao ; Jinyu Wen
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 2977 –2985
- DOI: 10.1049/iet-rpg.2019.0360
- Type: Article
- + Show details - Hide details
-
p.
2977
–2985
(9)
The demand response, providing the reserve service, becomes more and more important in the wind-power-integrated power systems. This study proposes a two-stage stochastic unit commitment model with the air conditioning (AC) aggregators providing the reserve service. A classification compensation scheme is proposed to promote AC users to provide more reserve capacity, which quantifies the users' comfort and their contribution to the system. Besides, a new AC scheduling method with adaptive response capacity (ARC) is proposed to help system operators to determine reasonable reserve capacity with smaller total cost. In addition, the inactive constraints identification is utilised to improve computational performance. Finally, the effectiveness of the proposed method is tested on the modified IEEE 118-bus system with 50 AC aggregators. The simulation results show that the proposed classification compensation scheme and the ARC method can promote more AC response capacity and save the total and reserve costs. The price game between the AC aggregators and the thermal units have a great impact on the decision results. The inactive constraints identification can save the total time by about 70%.
- Author(s): Renxin Yang ; Gang Shi ; Xu Cai ; Xiaoping Zhang
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 2986 –2993
- DOI: 10.1049/iet-rpg.2019.0332
- Type: Article
- + Show details - Hide details
-
p.
2986
–2993
(8)
The offshore all-DC wind farm with increasing capacity will bring problems such as the weakening of grid frequency stability and the increase of equivalent grid impedance. To overcome this, a coordinated control strategy for the offshore all-DC wind farm is proposed here with two salient features: better performance under weak grid condition and real-time frequency support from the wind farm. The control strategy consists of three parts: the inertia synchronising control of the receiving-end converter, the constant ratio control of the DC transformer and the frequency response of the wind farm. With the proposed strategy, the all-DC wind farm operates like a synchronous generator to the onshore grid, which provides fast frequency support when the onshore grid frequency changes. The effectiveness of the proposed method is validated in power systems computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) using a typical IEEE 9 bus system.
- Author(s): Jianing Gao ; Bei Han ; Lijun Zhang ; Chenbo Xu ; Guojie Li ; Lin Feng ; Keyou Wang
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 2994 –3001
- DOI: 10.1049/iet-rpg.2019.0352
- Type: Article
- + Show details - Hide details
-
p.
2994
–3001
(8)
The increasing wind capacity integration brings new challenges to power system planning and operation, due to the intermittency and uncertainty of its power generation. This study determines the optimal allocation of wind capacity in microgrids, with considerations of the impact of generation uncertainty on both static and dynamic performance of the system, for reducing the possible violations of operation limits caused by wind power fluctuations. The system performance under uncertainty is evaluated using a zonotope-based set-theoretic method. The uncertain variations of wind power are modelled by a zonotope, then the uncertainty sets of static and dynamic state variables, which capture all possible values of the system states, are further calculated by set operations and are embedded in the optimisation model as constraints for system performance. The proposed method is applied to a 33-bus microgrid; the results prove the validity of the method and show that the system can be guaranteed to operate within acceptable security regions in all possible situations when subjected to certain level of uncertainty.
- Author(s): Mohammad Al-Soeidat ; Tian Cheng ; Dylan Dah-Chuan Lu ; Vassilios G. Agelidis
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3002 –3008
- DOI: 10.1049/iet-rpg.2019.0359
- Type: Article
- + Show details - Hide details
-
p.
3002
–3008
(7)
Solar cell power performance is greatly affected by two critical factors ageing and crack. In order to mitigate their negative effects on the solar system, these cells are to be substituted by new cells, thus, replacing the panels. This study presents an active crack detection method that detects the cracked cells within a solar string by using AC parameter characterisation without a need to have a physical inspection. The mathematical module of the solar cell shows that it constitutes of series and parallel resistors in addition to a parallel capacitor and that their values change by ageing and crack. In addition to studying the effects of the crack on the solar cell, it is verified by the experiment that the solar cells behave as a capacitive circuit, and their capacitance increases when the cell gets cracked, getting higher as the crack becomes more serious. The experiment is extended to investigate the effect of series and parallel PV strings, which are affected by cracked and partially shaded cells to evaluate their criticality levels. By monitoring the AC parameter of the solar cell and the change of the capacitance, it is easy to detect the crack when it occurs.
Guest Editorial: Selected Papers from the 7th IET Renewable Power Generation Conference (RPG 2018)
Investigation on SSCI between PMSGs-based wind farm and AC network
Frequency-coupled impedance model-based sub-synchronous interaction analysis for direct-drive wind turbines connected to a weak AC grid
Stochastic unit commitment with air conditioning loads participating in reserve service
Voltage source control of offshore all-DC wind farm
Zonotope-based method for optimal allocation of wind capacity in microgrids considering generation uncertainty
Experimental study of static and dynamic behaviours of cracked PV panels
-
- Author(s): Rana A. Maher ; Ahmed K. Abdelsalam ; Yasser G. Dessouky ; Aziz Nouman
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3009 –3021
- DOI: 10.1049/iet-rpg.2019.0157
- Type: Article
- + Show details - Hide details
-
p.
3009
–3021
(13)
Wind energy conversion systems (WECSs) accommodate promising position in global energy market. Due to the dependency of the extracted wind power on various environmental aspects, as wind speed, the relation between the wind power and the turbine speed is highly non-linear. Hence, maximum power point tracking (MPPT) techniques are mandatory. Conventional perturb and observe MPPT technique suffers well-known oscillation-settling time trade-off. In this study, a state-flow based wind MPPT technique is proposed offering two degree of freedom, namely dedicated sample time and super-stepping as WECS is considered to be multi-rate multi-input single-output control system. In addition to being graphically user-friendly and written-code-free, the presented technique offers enhanced operation, minimal oscillations and fast response. Simulations, in addition to experimental results, covering various operating conditions are presented to advocate the effectiveness of the proposed technique.
- Author(s): Pablo García-Triviño ; Juan P. Torreglosa ; Francisco Jurado ; Luis M. Fernández Ramírez
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3022 –3032
- DOI: 10.1049/iet-rpg.2019.0766
- Type: Article
- + Show details - Hide details
-
p.
3022
–3032
(11)
This study presents a new energy management system (EMS) for the optimised operation of power sources of a hybrid charging station for electric vehicles and fuel cell vehicles. It is composed of a photovoltaic (PV) system, a battery and a hydrogen system as energy storage systems (ESSs), a grid connection, six fast charging units and a hydrogen supplier. The proposed EMS is designed to reduce the utilisation costs of the ESS and make them work, as much as possible, around their maximum efficiency points. The optimisation function depends on a cost prediction system that calculates the net present cost of the components from their previous performance and a fuzzy logic system designed for improving their efficiency. Finally, a particle swarm optimisation algorithm is used to solve the optimisation function and obtain the required power for each ESS. The proposed EMS is checked under Simulink environment for long-term simulations (25 years). By comparing the EMS with a simpler one that optimises only the costs, it is proved that the proposed EMS achieves better efficiency of the charging station (+7.35%) and a notable reduction in the loss of power supply probability (−57.32%) without compromising excessively its average utilisation cost (+1.81%).
- Author(s): Mohammed Elgeziry ; Mahmoud Elsadd ; Nagy Elkalashy ; Tamer Kawady ; Abdel-Maksoud Taalab ; Mohamed A. Izzularab
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3033 –3042
- DOI: 10.1049/iet-rpg.2018.6265
- Type: Article
- + Show details - Hide details
-
p.
3033
–3042
(10)
High-voltage direct current (HVDC) transmission systems are nowadays ideal candidates for interconnecting renewable energy resources to the electrical grids. This study presents a communication-less protection scheme for HVDC transmission systems with a multi-terminal voltage source converter (VSC). The existence of a tie-busbar is also considered, which represents a challenge for protection selectivity functions without the aid of a communication channel. The proposed scheme identifies the faulted segment on either a DC busbar or a line segment based on monitoring the calculated rate of change of the current-to-voltage ratio. This criterion is sensitive to detect the faults as the current increases rapidly in a few milliseconds, while the voltage decreases in the same time frame remarkably. Once the fault detection criterion is satisfied, the faulted section can be identified by checking the summation and direction of all branch currents at each busbar individually without utilising communication links. For investigation purposes, the proposed scheme is tested via a four-terminal HVDC system with two tie-busbars. Different simulation cases are evaluated with a variety of fault conditions using MATLAB/SIMULINK. The results corroborate the reliability, security, and efficacy of the proposed protection scheme for multi-terminal HVDC transmission systems.
- Author(s): Antonio Rosales ; Ziwei Yu ; Pedro Ponce ; Arturo Molina ; Raja Ayyanar
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3043 –3049
- DOI: 10.1049/iet-rpg.2019.0245
- Type: Article
- + Show details - Hide details
-
p.
3043
–3049
(7)
The presence of distributed generators (DGs) based on renewable energy is a fact in the electrical grid. However, DGs based on renewable resources such as photovoltaic panels and storage systems lack inertia, which is used by synchronous generators to compensate oscillations in the electrical grid. Thus, virtual inertia is introduced via a virtual synchronous generator (VSG) scheme. Although VSG is widely used, its robustness cannot be ensured since it employs proportional–integral–derivative-type (PID-type) controllers, which are sensitive to parameters variations. Furthermore, PID-type controllers are designed assuming balance conditions and the negative sequence components produced during unbalanced conditions are not considered. This paper proposes a robust VSG topology working under unbalanced conditions. A sliding mode control (SMC) algorithm named super-twisting (ST) is integrated into the control loop of VSG providing insensitivity to matched disturbances/uncertainties and finite-time convergence. Since the design of the ST algorithm considers the presence of negative-sequence components, it is not necessary a modification of the control loop before, during, or after the fault. The method to compute the ST control gains and the stability test using Lyapunov are provided. The VSG scheme is tested via simulations, where voltage sags are applied to generate the unbalanced conditions.
- Author(s): Liang Qin ; Yindi Xiong ; Kaipei Liu
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3050 –3060
- DOI: 10.1049/iet-rpg.2019.0263
- Type: Article
- + Show details - Hide details
-
p.
3050
–3060
(11)
The sample division-based hybrid model is an enforceable approach to improve wind power forecasting accuracy in the short term. These models up to now prefer to keep the input same for all the individual schemes, which weaken the effort of division and restrict the further improvement of the accuracy. To this end, a weather division-based wind power forecasting model with ensemble feature selection is proposed for refinement. The methodology comprises three stages: the division of wind power associated weather based on hierarchical clustering with the DTW distance metric, ensemble feature selection framework considering both predictive accuracy and stability, and wind power prediction based on machine learning algorithms for each weather type. As a test case, the proposed methodology is applied to the data of a wind farm group in Northwest China. With respect to the single models, the proposed method has improved the predictive accuracy by up to 30% at three error metrics, and the weather associated features are discussed.
- Author(s): Jianquan Zhu ; Xiemin Mo ; Tao Zhu ; Ye Guo ; Tianyun Luo ; Mingbo Liu
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3061 –3070
- DOI: 10.1049/iet-rpg.2019.0536
- Type: Article
- + Show details - Hide details
-
p.
3061
–3070
(10)
This study focuses on the real-time operation of a microgrid (MG). A novel approximate dynamic programming based spatiotemporal decomposition approach is developed to incorporate efficient management of distributed energy storage systems into MG real-time operation while considering uncertainties in renewable generation. The original dynamic energy management problem is decomposed into single-period and single-unit sub-problems, and the value functions are used to describe the interaction among the sub-problems. A two-stage procedure is further designed for the real-time decisions of those sub-problems. In the first stage, empirical data is utilised offline to approximate the value functions. Then in the second stage, each sub-problem can make immediate and independent decision in both temporal and spatial dimensions to mitigate adverse effects of intermittent renewable generation in a MG. No central operator intervention is required, and the near optimal decisions can be obtained at a very fast speed. Case studies based on a six-bus MG and an actual island MG are conducted to demonstrate the effectiveness of the proposed algorithm.
- Author(s): Elena Memmel ; Dorothee Peters ; Rasmus Völker ; Frank Schuldt ; Karsten von Maydell ; Carsten Agert
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3071 –3079
- DOI: 10.1049/iet-rpg.2019.0218
- Type: Article
- + Show details - Hide details
-
p.
3071
–3079
(9)
The progressing integration of renewables (RE) into distribution grids leads to bidirectional power flows. Due to the fact that the power infeed by RE exceeds the grid capacities, bottlenecks occur increasingly and thereby renewable power generation has to be curtailed. For the decision if countermeasures like flexibility options could be applied, the knowledge of the amount of curtailed power as well as its local and temporal availability is crucial. This study proposes an approach to determine the curtailed power characteristics, which creates time series simulating the potential vertical power flow at medium voltage/ high voltage (MV/HV) transformers without curtailment. The approach is thereby modular and adjustable to the investigated (or any other) grid, so it achieves a high precision. The power flow at these transformers is modelled by load profiles and power curves of connected RE, which are adjusted individually for each transformer on the basis of the corresponding historical power flow. For validation, the transformers are clustered corresponding to their power flow characteristics and the uncertainty is determined for each cluster. Modelled wind power shows a mean deviation below 2% of total installed wind power. Thereby, the presented modelling approach is able to determine the curtailed power in regions with wind power-related curtailments.
- Author(s): Xinchi Wei ; Ming Cheng ; Rensong Luo ; Litong Xu ; Jianguo Zhu
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3080 –3087
- DOI: 10.1049/iet-rpg.2019.0566
- Type: Article
- + Show details - Hide details
-
p.
3080
–3087
(8)
This study presents a model predictive virtual power control (MPVPC) method for brushless doubly-fed induction generator (BDFIG) during the grid synchronisation process. Predictive virtual power model is developed for the first time based on the defined virtual power and state-space equation of BDFIG. The control characteristics of virtual power are analysed to explain clearly how to realise grid synchronisation condition through the control of virtual power. The MPVPC controller is then designed to unify the control structure during the transition from the grid synchronisation mode to the grid connected mode, and only flux feedback needs to be changed between these two modes. The consistency between theoretical analysis and actual performance is confirmed by the results of both numerical simulation and experimental tests. As demonstrated, the proposed MPVPC controller can achieve fast and smooth grid synchronisation and excellent decoupled control of active power and reactive power.
- Author(s): Luis Sainz ; Lluis Monjo ; Marc Cheah-Mane ; Jun Liang
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3088 –3096
- DOI: 10.1049/iet-rpg.2019.0291
- Type: Article
- + Show details - Hide details
-
p.
3088
–3096
(9)
Converters are the key for increasing the development of renewable energy generation but their dynamic interaction with the grid has an important impact on stability. Oscillatory instabilities in different grid-connected converter systems at several frequency ranges are reported. In particular, sub and supersynchronous oscillatory instabilities in AC power systems with type-3 and type-4 wind turbine generators (WTGs) were recently registered at several wind farm areas. A number of works based on eigenvalue analysis and frequency domain approaches are carried out to analyse this new stability issue and more research is going on to analyse in detail the electric and control parameters that may affect this phenomenon. This study contributes analysing in detail the influence of system parameters on the subsynchronous oscillations (SSOs) in AC power systems with type-4 WTGs. This study is based on a new approach for subsynchronous stability assessment which could also be used for analysing other types of SSOs (e.g. subsynchronous control interactions between doubly-fed induction generators and series-compensated networks) as well as supersynchronous oscillations. A representative example of weak AC grids with type-4 WTGs is used to illustrate the contributions of the study. Results are validated with PSCAD/EMTDC time-domain simulations.
- Author(s): Ziqi Liu ; Junjie Yang ; WenZhan Song ; Naifan Xue ; Shenglin Li ; Mingshuo Fang
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3097 –3105
- DOI: 10.1049/iet-rpg.2019.0464
- Type: Article
- + Show details - Hide details
-
p.
3097
–3105
(9)
In residential microgrids, an energy storage system (ESS) can mitigate the intermittence and uncertainty of renewable energy generation, which plays an important role in balancing power generation and load consumption. Distributed energy storage (DES) is a common form of ESS. However, the high investment cost and fixed energy storage capacity limit their application in residential areas. This study proposes an improved service mechanism based on an alternative form of DES, cloud energy storage (CES). The energy transaction service is added in traditional CES service mechanism to enhance the power interaction between users. In addition, the pricing scheme of CES service fee is formulated, which is calculated based on the battery life loss caused by charging/discharging behaviour during the service period. This study considers that CES can improve energy storage utilisation and meet the energy storage requirements of users at a lower cost than DES. Finally, the CES service decisions are solved by the solver LINGO, including charging/discharging power decisions and energy trading decisions of users. Simulation results show that users' electricity costs are further reduced under the improved CES model. The rationality and economic feasibility of the improved CES model are demonstrated.
- Author(s): Shokoofeh Abbaszadeh ; Stefan Hoerner ; Thierry Maître ; Roberto Leidhold
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3106 –3112
- DOI: 10.1049/iet-rpg.2019.0309
- Type: Article
- + Show details - Hide details
-
p.
3106
–3112
(7)
This study reports on an experimental method to obtain the motion law of a pitch system required for maximising the power output of a vertical-axis water turbine (VAWT). In order to allow for the close monitoring of blade forces, the turbine is modelled with a single oscillating hydrofoil in a water channel. The pitch motion is controlled numerically, and the pitch angle and forces are measured as a function of time. The objective of the optimisation is to maximise the time integral of the thrust coefficient. The optimisation is based on a hardware-in-the-loop method and uses a multi-scale, full-factorial approach. The optimal motion law is found through successive improvements with an adaptive parameter step refinement, while the integral of the driving force coefficient is used as a target function. An optimal pitch trajectory with a significant improvement in the thrust coefficient was obtained for a single operating point. The benefit of this methodology is the possibility to study a complete range of turbine designs through the variation of two dimensionless parameters (tip–speed ratio and reduced frequency k), within very short runtime, minimising time and costs investigation, compared to more common numerical methods, or experiments on a complete VAWT.
- Author(s): Chunxia Dou ; Shengqi Teng ; Tengfei Zhang ; Bo Zhang ; Kai Ma
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3113 –3123
- DOI: 10.1049/iet-rpg.2019.0664
- Type: Article
- + Show details - Hide details
-
p.
3113
–3123
(11)
A layered management and hybrid control strategy based on hybrid automata and random forest for the microgrid is proposed in this study. It is used to realise energy management and multi-modal coordinated switching of microgrid system to ensure high security, stability and high efficiency. Management and control strategies are implemented through a three-layer microgrid architecture based on multi-agent system theory. An energy management strategy is designed for the microgrid system in the upper layer agent structure. A coordinated control strategy is designed in the middle layer agent structure. A local control strategy is designed into the bottom layer agent structure. In the middle layer coordinated control strategy, the hybrid automata is used to characterise the complex logical features of each underlying unit and trigger the switching of working modes according to the condition change. The random forest algorithm is used to analyse the running state and reduce the number of switching. Finally, the simulation results verify the effectiveness of the proposed control strategy in different scenarios.
- Author(s): Tania B. Lopez-Garcia ; Edgar N. Sanchez ; Riemann Ruiz-Cruz
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3124 –3132
- DOI: 10.1049/iet-rpg.2019.0581
- Type: Article
- + Show details - Hide details
-
p.
3124
–3132
(9)
In a renewable energy generation system, the batteries are one of the main components for energy storage. To maximise the useful life of batteries, it is important to ensure a safe and effective rate in the process of battery charging and discharging. To control these processes, different electronic circuits can be used, of which, the most commonly implemented is the DC–DC buck–boost converter. Two different topologies with their corresponding controllers are needed because the energy transfer is bidirectional. This work develops a unique neural inverse optimal controller with online identification for both charge and discharge processes of the battery bank. The main feature of the proposed controller is that it does not present dependence on the converter parameter variations; for this reason, it can be applied for systems with different power requirements without considerable changes in its application. This study discusses the development and real-time operation of a neural controller based on the inverse optimal control algorithm for charge–discharge of a battery bank.
- Author(s): Qin Jiang ; Baohong Li ; Tianqi Liu
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3133 –3141
- DOI: 10.1049/iet-rpg.2019.0610
- Type: Article
- + Show details - Hide details
-
p.
3133
–3141
(9)
The ultra-low-frequency oscillation (ULFO) problem reappears in China recently, but its specific mechanism is not so clear. Although the hydraulic governor system is confirmed as the source of ULFO, the parameters’ impacts are not studied thoroughly. This study investigates the specific impact of the important parameter of governing system in different control modes based on the complex coefficient torque method including the parameters of regulator, actuator and the turbine in hydraulic governing system. The damping torques under different situations are illustrated when parameters and control modes change, and the ultra-low-frequency-band dynamic characteristics of hydro generator are obtained. The simulations match well with the theoretical analysis, and the suggestions are made for parameter settings at last. The findings of this study are significant for ultra-LFO elimination. Moreover, it can also help designers and operator identify the most influential parameters and develop effective control strategies.
- Author(s): Quentin Deltenre ; Tim De Troyer ; Mark C. Runacres
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3142 –3150
- DOI: 10.1049/iet-rpg.2019.0032
- Type: Article
- + Show details - Hide details
-
p.
3142
–3150
(9)
As rooftops in cities are mostly underused, they have a large potential for decentralised electricity production. In that context, photovoltaic (PV) panels have proven to be an effective solution. Meanwhile, the market of small wind turbines is increasing, and some building owners have already installed one or more units on their roof. While the economic comparison between PV panels and wind turbines has already largely been addressed, in general, the space constraint of a rooftop has never been taken into account. In this work, the authors propose a methodology to compare the energy production and the return on investment both for rooftop-mounted PV panels and wind turbines. The comparison is made for relatively tall buildings (≥60 m) with good wind conditions (≥5 m/s annual mean wind speed). Using a brute-force approach, this study presents the results of the methodology applied to a case study: the Brussels Region. On tall rooftops, considering the space already taken by other installations and assuming an average wind speed of 5 m/s, small building-mounted wind turbines are shown to produce more energy than PV panels. Nevertheless, their return on investment is always lower than that of the PV panels.
- Author(s): Nilay Narendrakumar Shah and Sanjay.R. Joshi
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3151 –3167
- DOI: 10.1049/iet-rpg.2019.0256
- Type: Article
- + Show details - Hide details
-
p.
3151
–3167
(17)
This study modifies the IEEE first benchmark model (FBM) by connecting nearby doubly-fed induction generator (DFIG) wind farms to utilize the inbuilt convertor controller for damping the sub-synchronous resonance (SSR) oscillations. The overall model was evaluated to determine the induction generator effect (IGE) and torsional interaction (TI) of sub-synchronous resonance (SSR) at various compensation levels, wind speeds, and system parameter settings both with and without a DFIG wind farm. The results of this detailed analysis demonstrated that augmenting an IEEE FBM with a DFIG wind farm suppresses SSR-induced IGE in the power system. An optimal orientation was investigated from rotor-side converter (RSC) and grid-side converter (GSC) of DFIG wind farm using residue configuration to design a SSR supplementary damping controller (SSDC). To suppress the TI effect of SSR, the SSDC implements damping control using three different feedback signals: line current, line power, and voltage across a series capacitor. A robust signal for achieving smooth damping under various operating conditions was defined in terms of several key characteristics, namely, high average residue magnitude, average phase angle of residue and avoidance of destabilisation of other dominant modes. The proposed model was validated using eigenvalue analysis, participation factor calculation and time-domain simulation.
- Author(s): Ameena Saad Al-Sumaiti ; Mohammed Hassan Ahmed ; Sergio Rivera ; Mohammed Shawky El Moursi ; Mohamed M.A. Salama ; Tareefa Alsumaiti
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3168 –3179
- DOI: 10.1049/iet-rpg.2019.0345
- Type: Article
- + Show details - Hide details
-
p.
3168
–3179
(12)
Planning photovoltaic (PV) power systems integration into the grid necessitates accurate modelling of renewable power generation. Global solar irradiance, weather temperature and PV power losses due to overheating specifically in hot regimes are major factors contributing to PV power generation uncertainty. This study targets demonstrating the effectiveness of deploying advanced five parameter probabilistic distribution ‘Wakeby’ for modelling PV uncertain power generation, measured as a function of such factors, in power system planning applications. The impact of different approaches for incorporating weather temperature on PV energy estimation is studied. Wakeby-Monte Carlo Simulation for PV power data training with an emphasis on MCS stopping criteria for such advanced distribution is presented. The model is tested and verified in 31-bus distribution system to demonstrate its effectiveness over other literature uncertainty modelling approaches when planning integration of PV systems' integration into the grid to minimise the grid losses cost. Real PV power measurements are utilised as benchmark verifying the accuracy and suitability of the presented uncertainty modelling approach. Simulation results demonstrate a small error of $4.7 in the expected annual cost of grid losses when deploying Wakeby model compared to the benchmark case and that error can vary significantly when deploying other PV models.
- Author(s): Ancha Satish Kumar and Bibhu Prasad Padhy
- Source: IET Renewable Power Generation, Volume 13, Issue 16, p. 3180 –3190
- DOI: 10.1049/iet-rpg.2019.0027
- Type: Article
- + Show details - Hide details
-
p.
3180
–3190
(11)
This study presents a novel adaptive droop control (ADC) strategy for power-sharing in a multi-terminal high-voltage DC grid while maintaining a desirable DC voltage level. The ADC scheme can share the power without burdening any power converters during one or more converter outages and huge power imbalance situations. To improve the effectiveness of the power sharing and DC voltage deviation control, the ADC is also implemented for wind farm converters. This is achieved through a derated mode operation of wind farms. The performance and effectiveness of the proposed control approach are evaluated in several case studies based on the specific type of converter outage under the various outage scenarios. The proposed method is validated on a five-terminal CIGRE B4 DC grid test system.
High performance state-flow based MPPT technique for micro WECS
Optimised operation of power sources of a PV/battery/hydrogen-powered hybrid charging station for electric and fuel cell vehicles
Non-pilot protection scheme for multi-terminal VSC–HVDC transmission systems
VSG scheme under unbalanced conditions controlled by SMC
Weather division-based wind power forecasting model with feature selection
Real-time stochastic operation strategy of a microgrid using approximate dynamic programming-based spatiotemporal decomposition approach
Simulation of vertical power flow at MV/HV transformers for quantification of curtailed renewable power
Model predictive virtual power control of brushless doubly-fed induction generator for fast and smooth grid synchronisation
Assessment of subsynchronous oscillations in AC grid-connected VSC systems with type-4 wind turbines
Research on cloud energy storage service in residential microgrids
Experimental investigation of an optimised pitch control for a vertical-axis turbine
Layered management and hybrid control strategy based on hybrid automata and random forest for microgrid
Real-time implementation of battery bank charge–discharge based on neural inverse optimal control
Investigation of hydro-governor parameters’ impact on ULFO
Techno-economic comparison of rooftop-mounted PVs and small wind turbines: a case study for Brussels
Analysis, reduction and robust stabiliser design of sub-synchronous resonance in an IEEE FBM augmented by DFIG-based wind farm
Stochastic PV model for power system planning applications
Adaptive droop control strategy for autonomous power sharing and DC voltage control in wind farm-MTDC grids
Most viewed content
Most cited content for this Journal
-
Integration of renewable distributed generators into the distribution system: a review
- Author(s): T. Adefarati and R.C. Bansal
- Type: Article
-
Artificial neural network-based photovoltaic maximum power point tracking techniques: a survey
- Author(s): Lina M. Elobaid ; Ahmed K. Abdelsalam ; Ezeldin E. Zakzouk
- Type: Article
-
Improved performance low-cost incremental conductance PV MPPT technique
- Author(s): Nahla E. Zakzouk ; Mohamed A. Elsaharty ; Ahmed K. Abdelsalam ; Ahmed A. Helal ; Barry W. Williams
- Type: Article
-
Optimal operation of distributed generations in micro-grids under uncertainties in load and renewable power generation using heuristic algorithm
- Author(s): Nima Nikmehr and Sajad Najafi-Ravadanegh
- Type: Article
-
Solution to short-term frequency response of wind farms by using energy storage systems
- Author(s): Ju Liu ; Jinyu Wen ; Wei Yao ; Yao Long
- Type: Article