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In this article, a vector proportional–integral (VPI) current controller for the LC-coupling hybrid active power (LC-HAPF) with ideally zero steady-state error, optimal transient response, and good robustness is proposed. First, the transfer function of the proposed VPI current controller is introduced, and its parameter design for obtaining optimal transient response is discussed. Second, a detailed robustness analysis of the VPI current controller, including the system parameter variation, distorted grid voltage, and grid frequency variation conditions, is proposed. Third, the digital implementation method of the VPI controller and an overall control block diagram for the LC-HAPF with the proposed VPI current controller are presented. Moreover, a comparative study and analysis between the VPI current controller and the other representative current controllers under the minimum dc-link voltage is discussed in which the VPI current controller obtains the best performances under the minimum dc-link voltage operation. The simulation and experimental results are provided to verify the advantages and effectiveness of the proposed VPI current controller for a three-phase four-wire LC-HAPF in comparison with the other representative current controllers under different dc-link voltage conditions. Finally, the robustness under different grid conditions and unbalanced compensation capability of the proposed VPI-controlled LC-HAPF are also verified by the experimental results. [ABSTRACT FROM AUTHOR]

• A two-layer framework is proposed for building HVAC and associated multi-energy consumption optimization. • 100% renewable complementarities are proposed for building multi-energy supplies. • A R-C thermodynamic network is formulated to model the building HVAC. • AC slow charging and DC fast charging types of EVs are considered and managed via a novel real-time supply–demand pricing. Building heating, ventilation, and air conditioning (HVAC) and associated energy consumption make up the more and more important part of the world, whose reduction provides a cost-effective path to the "dual carbon" goal. This paper proposes a two-layer management of HVAC-based multi-energy buildings under proactive demand response of fast/slow-charging electric vehicles (EVs). In this paper, the building HVAC is mathematically formulated via a R-C thermodynamic model, which coordinates with multi-energy converters and storages to form a 100% renewable building. The building management is a challenging optimization problem due to its severe constraints and strong spatio-temporal couplings. In the first layer, a day-ahead multi-energy dispatch is formulated to economically optimize the electrical, heat, gas energy carriers. In the second layer, alternating current (AC) slow charging and direct current (DC) fast charging types of EVs are considered and managed via a novel real-time supply–demand pricing mechanism. After acquiring the economical dispatch references in the first layer, the second layer implements a model predictive control (MPC)-based real-time scheduling to handle the multi-energy supply–demand fluctuations. The original two-layer optimization is further handled via mixed-integer linear program (MILP) reformulation for high-efficient solving. Comparisons have shown the advantageous performances of the proposed two-layer optimization over economics and practicability. Simulations results show that the overall system operating cost can be reduced by at most 3.01% with a higher operational flexibility in building management. [ABSTRACT FROM AUTHOR]

In this article, a half-tangent phase-locked loop (HTan-PLL) is proposed for variable-frequency grids of more electric aircrafts. First, the pros and cons of the synchronous reference frame PLL (SRF-PLL) are discussed in a nonlinear framework. To address the disadvantages, a half-tangent phase detector (PD) is developed and a novel PLL is then proposed. Subsequently, a phase portrait-based analysis and a Lyapunov function-based argument are provided. It is proven that the HTan-PLL has a good performance in terms of steady-state accuracy and fast dynamics, even under large frequency changes. Compared with the conventional SRF-PLL, the proposed HTan-PLL outperforms with the following features: faster dynamics than the SRF-PLL when the frequency varies largely; no unstable equilibrium points, while the SRF-PLL has infinite unstable equilibrium points; and when the grid frequency jumps widely, the HTan-PLL converges to the unique equilibrium point (0,0). By contrast, the SRF-PLL goes to different equilibrium points. Experimental tests are provided, which verify the superior performance of the HTan-PLL. [ABSTRACT FROM AUTHOR]

The intelligent substations should be developed to perform multifunction operations, including power flow control, voltage regulation, and cost-effective power quality (PQ) improvement. In this article, an intelligent substation by a distribution transformer integrated with a capacitive-coupling winding tap injection static synchronous compensator (CWTI-DSTATCOM) is proposed for balance and unbalance operations. Compared with the state-of-the-art approaches, CWTI-DSTATCOM can operate at a low dc voltage with a small active inverter rating, which also can provide distributed voltage, reactive, and unbalanced current compensation. The power rating reduction mechanism is mathematically revealed via balance and unbalance compensation analysis, which is further used to determine the optimal inverter power rating of unbalance operation via an optimal LC filter design method. Furthermore, a comprehensive compensation control strategy is developed to coordinate the transformer taps and the active inverter under balanced and unbalanced operations. Simulation and real-time digital simulator hardware-in-the-loop experiments are performed to prove the validity and effectiveness of the proposed topology over inverter rating reduction and PQ enhancement. [ABSTRACT FROM AUTHOR]

A finite-set model predictive control (FS-MPC) with coupling capacitor voltage observer scheme is proposed for thyristor-controlled LC-coupling hybrid active power filter (TCLC-HAPF) in this article. It ensures the fast transient response, low steady-state error, and good robustness under both inductive and capacitive load situations. Generally, the implementation of FS-MPC for TCLC-HAPF requires sensing of coupling capacitor voltage and thyristor-controlled reactor current in addition to sensing load voltage, load current, and compensation current, which increases the system complexity and cost. To relax this problem, the simplified predictive model is first proposed, thus reducing the required sensing signals and system order. Then, a coupling capacitor voltage observer is utilized to reduce the hardware costs, which can obtain a comparable performance with directly sensed capacitor voltage. The delay compensation is also considered for the control delay in practical realization. Finally, the effectiveness and performance of the FS-MPC with coupling capacitor voltage observer for TCLC-HAPF are verified by simulated and experimental results. [ABSTRACT FROM AUTHOR]

In high-power applications, different multilevel voltage source converter (VSC) topologies are usually applied. The hybrid parallel multiconverters, which is a combination of multiactive and hybrid VSCs connecting in parallel, can be a promising solution in a high-power grid. In this article, the fusion VSC topology concept is proposed in which fusion VSC takes the advantages of both active (inductive coupling) VSC and hybrid (capacitive coupling) VSC. It corresponds to overcoming the insufficient-capacity problems when active VSCs are employed alone and vice versa. This article proposes fusion active power filter topology by combing active and hybrid power VSC through their equivalent model for power quality compensation. With the proposed VSC's equivalent model, it can reduce the converter rating by 17%–80% compared with the conventional approaches. Additionally, the corresponding control algorithm is proposed for the FAPF for power quality compensation. Finally, the simulation and real-time digital simulator hardware-in-the-loop experimental results of the proposed FAPF topology are given to demonstrate the validity and effectiveness for reducing its capacity and power loss compared with the conventional multi-VSC in power quality compensation. [ABSTRACT FROM AUTHOR]

Compared with the conventional active power filter, the thyristor-controlled LC-coupling hybrid active power filter (TCLC-HAPF) has a distinct characteristics of low dc-link operating voltage, which can lower the system and operational costs in the medium-voltage-level system. It also has a wider operational range than the conventional hybrid active power filter. Besides that, the TCLC-HAPF can provide reactive, harmonic, and unbalanced powers compensation simultaneously. In this article, the modeling of the TCLC-HAPF is investigated based on the linear control aspect. Then, the analysis, design, and implementation of a multi-quasi-proportional-resonant (MQPR) controller with gain scheduling for the TCLC-HAPF will be proposed, which can automatically change the resonant gain between the inductive and capacitive loads operation to improve its compensation performances. The proposed controller can significantly reduce the TCLC-HAPF steady-state current tracking errors and output current ripple. Finally, the simulation and experimental results are also provided to verify the effectiveness and performance of the MQPR controller for the TCLC-HAPF in comparison with the hysteresis current controller and quasi-proportional-resonant (QPR) controller, which shows superior compensating performances. [ABSTRACT FROM AUTHOR]