IET Energy Systems Integration最新文献

To enhance the robustness of the unified power quality conditioner (UPQC) with finite control set model predictive control (FCS-MPC), direct control in the dq coordinate system faces challenges such as complex coordinate transformation, system coupling issue and phase-locked-loop delays. In this study, a predictive direct control strategy based on an ultra-local model (ULM) is proposed. A model-free parametric predictive direct current control scheme for the UPQC within the αβ framework is crafted by amalgamating an ultra-local model with predictive direct control. Derived from the generalised instantaneous power theory and the active power equilibrium within the UPQC system, the current command generation mechanism of UPQC is established, and the parallel active power filters (PAPF) current command generation mechanism is developed by integrating dead-beat control alongside the strategy for maintaining a consistent baseline voltage magnitude for the connected load. This approach effectively navigates the complex coordinate transformation and system coupling issue, realises no phase-locked loop, no system parameters and no PI outer-loop controller control and simplifies the control system structure. Simulation results show that even with 50% parameter mismatch, the proposed strategy can still maintain the grid current THD at < 2%. Finally, we verify the feasibility of the strategy through simulations and experiments.

To address grid instability caused by intermittent renewable energy, this work proposes utility-scale battery energy storage (BES) integration using a hybrid multilevel and multipulse voltage source converter (VSC) topology, which overcomes the limitations of conventional converters in efficiency, scalability and harmonic performance for high-power, high-voltage applications. VSC employs 13-level H-bridge converters and 30-pulse high voltage converters to mitigate voltage harmonics. By combining multipulse technique with selective harmonics elimination, low total harmonic distortion is achieved for VSC output voltage and grid currents. Utilising multiple cascaded H-bridge (CHB) converters and transformers increases VSC power and energy capacity for BES plant to deliver energy at a 400-kV voltage level to grid. A 1000-MW VSC with a 6000-MWh BES plant is simulated in MATLAB and implemented on a real-time platform to study its steady-state, harmonics and dynamic performances.

Under the background of the low-carbon strategy and power market reform, multiple virtual power plants (MVPP) will coexist in the distribution network in the future. In order to improve the energy utilisation rate and the autonomy of virtual power plant (VPP) under the high proportion of renewable energy sources, and solve the conflict of interest and information asymmetry among MVPP, a mixed game dual-layer energy optimisation operation strategy between the distribution network and MVPP with the consideration of environmental benefits under the background of cloud energy storage operator (CSO) is proposed. First, a Stackelberg game dual-layer energy trading model is constructed to maximise the benefits of the upper layer and minimise the cost of the lower layer. Second, a cooperative game among members of the VPP is introduced to enable peer-to-peer trading among MVPP, and a mixed game optimisation model is established. The joint operation of the waste incineration power plant and carbon capture system is introduced into the VPP, which takes into account the economy and low carbon of the system. Then, according to the characteristics of the model, the Stackelberg model is solved by using the genetic algorithm combined with CPLEX, and the cooperative model is solved by using the alternating direction method of multipliers. The dual-layer models interact with each other, and the balanced optimal operation strategy of the CSO, MVPP and mixed game model within the MVPP is obtained. Finally, the feasibility and effectiveness of the strategy are verified by simulation examples. The low-carbon mixed game strategy proposed in this paper effectively improves the interest of CSO and MVPP, protects the data privacy of members and improves the autonomy of VPP.

Investigation of power converters for use in industrial drive applications finds that these converters are used low reliable components. To overcome this issue, in this paper, advanced power converters (multi-pulse AC–DC and multilevel DC–AC converter) are developed and implemented to feed vector-controlled induction motor drive (VCIMD), which enhance power quality of medium voltage drive system. Multi-winding transformers with multiphase conversion as well as phase displacement technique for multi-pulse AC–DC converters are designed. Hence, to attain high power quality at grid side, while drive system is designed with the few numbers of DC sources, a multiphase conversion and phase displacement techniques-based 50-pulse rectification system is designed and developed here. For it, circuit structure of five multi winding transformers (T₁, T₂, T₃, T₄, T₅) is developed through phase displacement and multiphase conversion (3- phase to 5-phase) technique instead utilising low reliability components. Apart from this, to overcome the challenges at the drive side, a six-level cascaded multilevel inverter is developed with a low number of components. The rigorous design of a 50-pulse AC–DC converter and six-level cascaded inverter-based medium voltage drive system is made and responses of this system are analysed through experiments (7.5 kW IM) at various operating conditions. In verification processes, operation principle and impact of converters utilisation are clearly analysed. More importantly, using proposed circuitry, the input current is almost sinusoidal; its input current total harmonic distortion is less than 5%. Hence, the presented drive system addresses power quality standard IEEE 519 in the system.

Frequency stability is vital to power system operation, especially in interconnected power systems (IPS) and smart grids where renewable energy sources and load fluctuations introduce unpredictability. This variability and time delay from decentralised control configurations can impair load frequency control (LFC) and compromise system stability. This study proposes a robust adaptive integral terminal sliding mode controller (RAITSMC) for LFC to address these challenges. The controller mitigates destabilising effects from time delays, parametric uncertainties and nonlinear disturbances. A delay-dependent sliding surface is developed to enhance the system's response to tie-line power and frequency deviations. Perturbations are estimated using an adaptation law, and a decentralised robust control law ensures the system's trajectory remains on the sliding surface with minimal control efforts. The controller's stability is validated via the Lyapunov theorem, and its parameters are optimised using the arithmetic optimisation algorithm. Simulations on the IEEE 10-generator New England 39-bus power system demonstrate significant improvements, including reduced frequency overshoot (48.3%), undershoot (45.7%) and settling time (37.2%), along with enhanced robustness under $��\pm �$50% parametric variations. Comparative analyses reveal superior performance across error-based indices, showcasing RAITSMC's potential to ensure a reliable and stable power system operation.

Power generation from inverter-based renewable energy sources (RESs), such as solar photovoltaics (PVs), is increasing rapidly in power systems while leading to operational challenges such as frequency regulation. Battery energy storage systems (BESS) have attracted much attention in providing frequency control ancillary services (FCAS), as they provide flexibility to store and release energy when required. With a larger inverter size and energy capacity, BESS can provide more frequency support to the grid but will incur large capital costs. Thus, it is important to minimise the size of the battery while ensuring system security requirements are fulfilled. In this paper, a large-scale BESS sizing framework is developed to obtain the optimal battery inverter size and energy capacity. The proposed framework determines the battery size based on two aspects: (i) contingency frequency control ancillary services (C-FCAS) to provide primary frequency support after a generator outage event and (ii) regulating frequency control ancillary service (R-FCAS) to match the power imbalance caused by the normal variation of load demand and RES generation. This paper also investigates the highest RES penetration level and the largest number of synchronous generators (SGs) that can be simultaneously reduced as the share of RESs increases. The effectiveness of the developed large-scale BESS sizing framework is tested on the Alice Springs power grid in Northern Territory, Australia. According to the study, the FCAS battery designed based on the proposed framework can fulfil the frequency support requirements under high solar-PV penetration in the Alice Springs power grid while significantly reducing the dependency on synchronous generators.

Supervisory Control and Data Acquisition (SCADA) systems monitor and control industrial processes, but their integration with information technology and network connectivity, including the internet, exposes them to potential cyber threats. As SCADA systems become essential infrastructure, their vulnerability to cyber-attacks has increased, necessitating a comprehensive understanding of potential risks. This paper presents a laboratory setup mimicking a real-world SCADA system, involving the simulation of an IEEE 14 Bus system integrated with IEDs. The communication link between the SCADA centre and IEDs is established through the MODBUS communication protocol. This paper further analyzes and detects cyber-attacks targeting SCADA systems, including Ping flood attack, UDP flood attack, Smurf attack, and Random flood attack. All these attacks are executed using Kali Linux tools. The Wireshark tool is employed to analyse network traffic and detect these attacks, which are also validated in real time using OPAL-RT (OP4510). The results demonstrate the successful implementation and detection of cyber-attacks, contributing to a deeper understanding of cyber threats and informing proactive security strategies to strengthen the security of Power SCADA systems against evolving cyber threats.

This paper presents hybrid quasi-Z-source converters (qZSCs) designed for integrated energy system-based microgrid applications, capable of providing dual-DC and multi-AC outputs from a single DC input source. Microgrids rely on diverse renewable energy sources such as solar and effective power converters and are crucial for integrating these resources into the grid. The proposed converters incorporate series and parallel-configured integrated inverters, facilitating both boost and buck-boost operations simultaneously with an additional inductive branch to the standard quasi-Z-source network. The suggested system utilises a novel control approach to regulate multiple AC and DC output voltages efficiently. Key features include robust power control, single-stage energy conversion, built-in shoot-through protection and immunity to electromagnetic interference. The proposed series and parallel converter circuits offer versatile configurations for generating two DC and multiple AC outputs, enhancing flexibility in microgrid power distribution. A closed-loop control strategy is implemented for the series qZSC to validate its operational effectiveness. Detailed steady-state mathematical analyses for both qZSC configurations are supplemented by simulation results under varying load conditions, confirming their performance capabilities. Additionally, for further validation, Hardware-in-the-loop (HIL) results were obtained with a real-time emulator using Typhoon HIL to prove the effectiveness of the proposed system.

Insufficient dissolved oxygen in aquaculture systems poses a significant challenge to sustainable fish farming, while traditional aeration systems rely heavily on grid electricity, contributing to both operational costs and environmental impact. This study addresses these challenges by integrating a compressed air oxygenation system with floating solar photovoltaic (PV) power generation, supported by deep learning-based forecasting for optimal system control. Our key contributions include: (1) development of an integrated floating PV-powered compressed air oxygenation system for aquaculture, (2) implementation and comparative analysis of three deep learning models (RNN, GRU and LSTM) for forecasting both PV power generation and compressed air production and (3) validation through a real-world case study in Thailand's Pathum Thani Province. The LSTM model demonstrated superior performance, achieving the highest accuracy with RMSE of 172.59 kW and MAPE of 13.87% for PV power forecasting, and a MAPE of 21.72% for compressed air production forecasting. The implemented system successfully improved water quality in a 1200-cubic-metre freshwater fish pond, increasing dissolved oxygen levels from 1.7 to 6.47 mg/L over a 4-month period. These results demonstrate the feasibility and effectiveness of renewable energy integration in aquaculture water treatment, offering a sustainable solution for fish farming operations while reducing dependency on grid electricity.

Multiterminal high-voltage direct current (MTDC) systems are anticipated to enable the massive integration of renewable energies into modern grids. However, the protection of MTDC systems is a major challenge for their application in connection with offshore wind farms (OWF). This is due to the extremely high short circuit currents, present for very short timeframes, and characterised by the absence of zero-crossing currents. Additionally, economic and technological issues further challenge widespread implementation of MTDC systems. The main constraints of MTDC protection coordination systems are generally associated with fault detection, DC reactor (DCR), DC circuit breaker (DCCB) operation time, and converter blocking time. This paper presents strategies for achieving full-selectivity (F-S) and partial-selectivity (P-S) in the protection of voltage source converter (VSC)-MTDC systems. A case study is setup to design both the F-S and P-S protection schemes. Initially, suitable DCRs are calculated for the case study, followed by selecting DCCB operation times with offshore converter blocking for both cases. Finally, an inverse time-current curve is proposed for different scenarios, considering sensitivity to DCR ratings to enhance converter blocking performance. The case study is conducted in PSCAD/EMTDC software and the simulation results demonstrate the impact of the different scenarios on the MTDC systems.