Power Distribution Control Strategy Research Articles

Research on secondary power allocation strategy of two types of energy storage units considering dual SOC

Abstract Against the problem of power fluctuation in the photovoltaic microgrid system, the power fluctuation can be smoothed out by hybrid energy storage technology. Still, the limited capacity of two energy storage units will cause safety problems, such as overcharging and over-discharging in two types of energy storage units and reduce the life of the energy storage device. Therefore, a secondary power distribution control strategy for two types of energy storage units considering dual SOC is proposed. Firstly, the system unbalanced power is calculated. The system unbalanced power is divided through the second-order low-pass filter to obtain the primary distribution power. Then, the SOC of the battery and supercapacitor is divided into nine regions. Finally, the power demand and the SOC in the nine regions are considered simultaneously. Then, the secondary power allocation is carried out for two types of energy storage units. In Matlab/Simulink, the modeling of Photovoltaic microgrids is established, and the simulation results verify the feasibility of the control strategy.

Optimal power distribution control in modular power architecture using hydraulic free piston engines

Vehicle modularization has become an emerging trend in the automotive industry, leading to research on modular configuration, composition, and related control strategies. In this paper, we propose a modular power system with a hydraulic free piston engine (HFPE) as the power unit and develop a power distribution control strategy to enhance the overall efficiency of the system. Firstly, we determine the configuration scheme of the modular power system and establish a simulation model of the HFPE using MATLAB/Simulink. We conduct principle verification of the simulation model. Secondly, based on the simulation model of HFPE, we research the power unit control strategy using the machine learning regression prediction algorithm, enabling dynamic working condition switching of the power unit. Next, we propose a power distribution optimization algorithm which is named as the Rule Based Double Iterative Optimization Algorithm (RBDI) and compare it with several mature optimization algorithms under the framework of model predictive control, considering related constraints. Finally, we validate the performance of the proposed power distribution control strategy using a hardware-in-loop system. The results demonstrate that the output power of the modular power system can be effectively ensured. Compared with the average distribution algorithm (AVE), the genetic algorithm (GA), and the ameliorated particle swarm optimization algorithm (APSO), the overall working efficiency of the modular power system using the proposed control strategy is increased by 6.57%, 6.13%, and 5.59%, respectively, under the three test driving cycles.

SOC Balanced Power Distribution Control Strategy of a DC–DC Converter with Virtual Synchronous Generator

The DC microgrid does not need to consider frequency when accessing distributed energy, but the distributed energy access port does not have inertia and damping characteristics, so there are problems of voltage instability and power fluctuation. In this paper, the bidirectional DC–DC converter is the main object; based on the virtual synchronous generator (VSG) control strategy, the inertia regulation is added to adjust the bus voltage dynamically. In addition, a balancing strategy is proposed to ensure the balanced distribution of the state of charge (SOC) and power for multiple batteries. Finally, a simulink is built to prove the viability and availability of the VSG control strategy.

Research on a new power distribution control strategy of hybrid energy storage system for hybrid electric vehicles based on the subtractive clustering and adaptive fuzzy neural network

Research on a new power distribution control strategy of hybrid energy storage system for hybrid electric vehicles based on the subtractive clustering and adaptive fuzzy neural network

Research on coordinated control strategy of isolated DC microgrid with PV/hybrid energy storage

During the operation of DC microgrid, energy storage system plays an important role in supplying the power difference between distributed generation unit and load and maintaining the voltage stability of DC bus, in recent years, hybrid energy storage technology has gradually attracted the attention of researchers. In this paper, a power distribution control strategy of hybrid energy storage system (HESS) is studied. The droop control based on virtual capacitor is used for the converter of supercapacitor (SC) to realize the power distribution in HESS, and the control strategy is improved to solve the problem that the deviation of bus voltage caused by droop control. Based on the control strategy of HESS, a coordinated control strategy of isolated DC microgrid is studied. By considering SOC of battery and the power demand of load, 3 operation modes of DC microgrid are set. DC microgrid can work in a designated mode under various conditions to achieve efficient and stable operation. Finally, the theory of the above control strategies is verified by the simulation work in RTDS and hardware-in-the-loop experiment based on DSP28335 and RTDS.

A two-layer control strategy of the wind farm participating in grid frequency regulation

This paper proposes a two-layer control strategy of wind farm participating in grid frequency regulation for problems caused by the direct switching of FR power distribution and wind turbine control strategy. At the wind farm layer, FR scenarios are divided. And a turbine grouping strategy is proposed according to the running status at the current and next moments, and the current system FR demand, i.e., increase or decrease power. According to the FR capability of wind turbines, the turbines are arranged to participate in FR in sequence. Consequently, the power support for the corresponding frequency fluctuation of the wind turbine is achieved, and the insufficient FR capacity caused by equal distribution is avoided. At the turbine layer, a proportional coefficient model is created based on the optimized combination FR mode of participating in FR. As a result, smooth switching of different FR modes is realized without modifying the original turbine structure. It makes upgrades simple and easy. A simulation model including four turbines and two domains is created in Matlab/Simulink, verifying the validity of the proposed strategy.

Reactive power sharing among distributed generators in a microgrid by using virtual current

This paper presents a new autonomous effective power distribution control strategy for three-phase parallel inverters. The proposal uses a controller that can provide the system with accurate power sharing among distributed generators installed in the microgrid once some load variations are presented in the network. The methodology uses a virtual current loop introduced into the current controller of the inverter to optimize the output signal, which goes directly to the PWM. This virtual current is obtained by using a virtual impedance loop. Furthermore, a small-signal model of the system is used to check stability of the proposed control strategy, which was developed for island mode operation of the microgrid. Simulations were performed for a microgrid with two generators and a load with five households and implemented in MATLAB/Simulink software. The results show that the model provides a wide margin of stability and a rapid response when electrical loads change, thus fulfilling the reactive power sharing among generators. The proposed method shows a large margin of stability and a rapid transient response of the system.

Research on the Power Distribution Method for Hybrid Power System in the Fuel Cell Vehicle

The power distribution strategy of hybrid power sources is an important issue for fuel cell vehicles. A good power distribution control strategy can realize the optimal control of the vehicle energy, which can save energy and improve the operating conditions of the power source. Therefore, this article proposes a power distribution strategy. First, in order to solve the problems existing in the existing fuel cell model and the lithium-ion battery model, an improved hybrid power system model with better dynamic performance was established in the Simulink. Second, in order to ensure the durability of the power system, operation constraints are added to the distribution strategy. Finally, the power allocation is regarded as a nonlinear programming optimization problem and solved by a nonlinear programming algorithm. The nonlinear programming algorithm selects the BFGS algorithm. The simulation results of other control strategies in MATLAB show that the proposed power distribution strategy greatly improves the durability of the vehicle and has good adaptability under urban conditions. This distribution method can provide support for the actual application of offline control strategies.

Motor Vector Control Based on Speed-Torque-Current Map

In order to effectively extend the mileage of pure electric vehicles, the influence of the electromechanical energy conversion principle and the dynamic control of a permanent magnet synchronous motor (PMSM) on the performance of pure electric vehicles are studied with a dual-motor drive system as a carrier in this paper. A vector control strategy based on the speed-torque-current map of a motor is proposed, considering the bus voltage fluctuation influenced by battery charge and discharge. By constructing a complete vehicle model including the dynamic control model of the motor, the power distribution control strategy of a dual-motor coupling mode considering the dynamic characteristics of the motor is developed and simulated on the MATLAB platform. The results show that the dynamic model of the motor is closer to the actual running conditions. The proposed control strategy effectively reduces the demand power, decreases the energy consumption of the electric drive system, and extends the mileage of the vehicle.

A Power Distribution Control Strategy Between Energy Storage Elements and Capacitors for Cascaded Multilevel Inverter With Hybrid Energy Sources

The key technology of a cascaded multilevel inverter with hybrid energy sources lies in the power distribution among different chains. A power distribution control strategy between the energy storage elements and the capacitors is proposed to achieve fault tolerant control. In the cascaded multilevel inverter with hybrid energy sources, the chains with energy storage elements can operate in four quadrants, while the chains with capacitors can only operate in two quadrants. With the proposed control method, the active power distribution is realized by active voltage vector superposition, and the reactive power distribution is achieved by initial operation point selection. This enhances both the system reliability and availability while enabling continuous operation in four quadrants. Meanwhile, the stable operation region and the range of the initial operating point have been derived by the vector analysis to avoid over-modulation. An experimental prototype based on a single-phase link with two series chains has been built in the laboratory. The simulation and experimental results are provided to demonstrate the effectiveness of the proposed control method.

An adaptive power distribution control strategy for an electric vehicle with dual-motor coupling in consideration of road gradient

An optimal power distribution control strategy is proposed in consideration of road gradient. Two original contributions are made to distinguish our work from current research. First, a sub-optimal State of Charge (SOC) predictive model is proposed based on Back Propagation (BP) neural network. The sampling set of the BP is obtained from the optimal results from Dynamic Programming (DP), based on a series of driving cycles in real-world and the corresponding road gradient. Second, an adaptive control method based on PID is proposed with the designed sub-optimal SOC predictive model. Specifically, the optimal shift schedule of the coupler is designed offline based on DP and is implemented into the controller in a prior fashion, to decouple the relationship between the coupler and the motors. Simulation results demonstrate that the proposed adaptive control strategy can realise optimally real-time power distribution control and is better than rule-based power distribution strategy.

An adaptive power distribution control strategy for an electric vehicle with dual-motor coupling in consideration of road gradient

An adaptive power distribution control strategy for an electric vehicle with dual-motor coupling in consideration of road gradient

Evaluation on the energy efficiency and emissions reduction of a short-route hybrid sightseeing ship

This paper is to develop a coordinated control strategy of a ship with hybrid power and evaluate on the energy efficiency and emissions reduction of the case ship. The hybrid power system consists of 4-stoke diesel generator, solar panels and battery packs. A micro-grid power system was structured to offer an optimal combination of the three power sources in terms high efficiency and low emissions of the overall system. The control requirements for the developed micro-grid power system were analysed according to the principles of priority to use renewable energy. A power distribution control strategy was designed by applying the logic threshold method. A system simulation model was established and the simulation was carried out with MATLAB. An experimental test rig was built to evaluate the simulation results and develop the control system. The developed marine micro-grids power system has been applied on a case ship and run stably. Compared with the conventional power system, the performance of emission and economic of the hybrid system is studied with the case ships. The results of case ship and experimental have shown that the developed hybrid micro grid system can be managed effectively by the proposed control strategy. The emission of CO2 is dramatically decreased in any cases and the energy cost is reduced considering for the ship life-cycle.

Modelling and control of a two-mode power-split hybrid powertrain

As one of the most efficient configurations hybrid powertrains, the power-split hybrid powertrain introduced in this paper has two electrically variable transmission modes. By controlling the speed and torque of each component, the powertrain can generate adequate output for the optimal operation of the vehicle. In this paper, detailed component models are first established and then integrated to an overall vehicle simulate model on Matlab/Simulink platform. Then, the mode selection scheme, rule-based power distribution control strategy, and mode transition control scheme are introduced. Finally, the performance of hybrid powertrain is studied by using the developed platform under typical operation condition. The work provides a support to design, test and development of hybrid powertrain through the implementation of a mathematical model to simulate the operation and predict the performance of the hybrid powertrain, and the platform enables users to estimate the impact of various control strategies on vehicle performance.

Optimum sizing and optimum energy management of a hybrid energy storage system for lithium battery life improvement

In this paper‎, ‎a formulation is developed for sizing of a Hybrid Energy Storage System (HESS) in different applications‎. ‎Here‎, ‎the HESS is a combination of Lithium battery and Ultra-Capacitor (UC)‎, ‎which is useful for many high energy and high power applications such as Hybrid Electric Vehicles (HEVs) and renewable energy‎. ‎The sizing formulas are based on initial cost and 10-years battery replacement cost which is arranged as an optimization problem‎. ‎For battery replacement cost‎, ‎the Lithium battery capacity depletion formulas are studied for a LiFePO4 battery‎. ‎As a case study‎, ‎application of HESS in a Series Hybrid Electric Bus (SHEB) is considered‎. ‎The results show by the addition of UC‎, ‎the Lithium battery life is improved significantly‎. ‎Furthermore‎, ‎the optimum sizing of the HESS is dependent to the SHEB driving cycle‎. ‎Therefore‎, ‎considering the power profile of the HESS in its sizing process may reduce HESS cost‎. ‎This effect is studied in three different cycles of the SHEB‎. ‎In addition‎, ‎the formulation is applied to cycle-based optimization of the Power Distribution Control Strategy (PDCS) of the HESS by dynamic programming‎. ‎The results show the optimum PDCS has better LiFePO4 battery life in comparison with the conventional PDCS‎.