Power Balance Model Research Articles

First Thomson scattering results from AWAKE’s helicon plasma source

Abstract We present the first results of electron density and temperature measurements obtained from Thomson scattering at the helicon plasma source (HPS) for the AWAKE project. These measurements are compared to simulation results from a 1D power and particle balance model (PPM), confirming that the plasma can be fully sustained by collisional power dissipation. The variations in plasma parameters under different experimental conditions are evaluated in the PPM framework. We discuss current limitations of the model and propose possible improvements. Additionally, we suggest modifications to the existing HPS setup to enhance axial plasma homogeneity.

Research on Electricity Balance and Measurement Optimization of New Energy Power System Considering Renewable Energy Consumption Mechanism

With the rapid development of renewable energy, the new energy power system is facing the challenge of large-scale grid connection and consumption of renewable energy. In order to achieve efficient utilization and stable power supply of renewable energy, this study proposes a renewable energy consumption mechanism based on optimization methods. By establishing a power and electricity balance model, consider the relationship between different types of renewable energy generation and electricity demand. Various optimization strategies have been proposed for energy consumption issues in different scenarios, including power generation scheduling, energy storage optimization, and flexible load management. Validate the effectiveness of the proposed mechanism in terms of electricity balance and metering optimization through a model. The experimental results indicate that this mechanism can effectively enhance the renewable energy consumption capacity of the new energy power system, reduce energy waste, promote energy cleanliness and sustainable development, and has certain theoretical and practical significance for promoting the sustainable development of the new energy power system and responding to energy transformation.

A Theoretical Investigation of an Ultrawide S-, C- and L-Band-Tunable Random Fiber Laser Based on the Combination of Tellurite Fiber and Erbium-Doped Fiber

In this paper, we present a new scheme to generate ultrawide tunable random fiber lasers (RFLs) covering the S-, C- and L-band by combining the broadband Raman gain in tellurite fibers and the active gain in erbium-doped fibers. A numerical simulation based on the power-balance model is conducted to verify the feasibility of the ultrawide tunable random fiber lasing generation. Pumped by a 1450 nm laser, the tunable random Raman fiber laser in the ranges of 1480–1560 nm and 1590–1640 nm can only be realized with a tellurite fiber. To further fill in the emission gap in the range of 1560–1590 nm, the erbium-doped fiber is incorporated in the cavity, which can provide efficient erbium-doped gain in the C- and L-band. By combining a 100 m long tellurite fiber and an 8 m long erbium-doped fiber, an ultrawide tunable RFL based on hybrid erbium–Raman gain can be realized with a wavelength tuning range (1480 nm–1640 nm) covering the S-, C- and L-band at 3.5 W pump power. Such a widely tunable RFL is of great importance in applications such as optical communication, sensing and imaging.

Research on the stability evolution mechanism and combinatorial optimization decision‐making of multitype heterogeneous energy cooperative operation

AbstractConsidering the cooperative willingness of multiple heterogeneous energy sources to participate in the alliance, the stability of the cooperative operation of each entity (hereinafter referred to as stability) and the supporting mechanism of its optimal combination to realize the high proportion of new energy generation are studied. Through simulating load peak‐cutting and valley‐filling in the power system, the difference between the load value and the base load in the 24 h of the daily load curve is used as the calculation condition for the supply balance of the alliance. Based on the source‐load power balance model, the feasibility of power data normalization is derived and demonstrated. Simultaneously, taking into account the time‐of‐use price cost of each entity, a multiscale operation cost allocation and stability evolution analysis model for the alliance is constructed using the Shapley value and the largest consistent set method. By comparing the willingness of each entity to engage in the alliance, as well as the multiscale operation stability and economic change rule of different alliances, the results demonstrate that: (1) Alliance 1 has the advantage of economic operation. (2) The common stability period of different alliances is influenced by the participation preferences of each entity (wind power, photovoltaic, and thermal power tend to participate in Alliance 1, while hydropower tends to participate in Alliance 2). (3) Alliance internal restructuring can be carried out by utilizing spatial and temporal difference characteristics of different entities’ participation in alliance preferences, thereby achieving alliance stability and efficient operation. This study provides a theoretical basis for making decisions regarding the optimized stable operation of the alliance.

Calculation of Power Purchase Imbalance Costs for Grid Enterprises’ Agents Considering Uncertainty of Supply and Demand and Price Fluctuations in the Context of Beijing-Tianjin-Tangshan Unified Spot

Abstract The regional unified electricity spot market plays an important role in promoting the optimal allocation of power resources over a wider range and cross-regional consumption of renewable energy. This paper examines the supply and demand uncertainty and price volatility of power grid agency power purchases in the context of the Beijing-Tianjin-Tangshan unified spot purchase. It delves into the specific mechanism of unbalanced costs in agency power purchase decisions and investigates the specific channeling methods of unbalanced costs in the dual-track system. Based on the dual-track unbalanced cost under the unified spot market, a dual-track power balance model is proposed based on the typical daily load curve, and a time-based unbalanced cost calculation model is designed. Using the typical daily electricity load data from the power supply enterprise in X province as an example, the calculation and simulation of unbalanced costs are carried out. The spot electricity price fluctuates between 0.25 yuan/(kW•h) and 0.45 yuan/(kW•h) in different periods. The overall unbalanced power purchased by the power grid in the load trough stage is only 6.24% of the total monthly electricity consumption. Still, the unbalanced cost in the study period is of a deficit nature, and its average value reaches −268 million yuan. The calculation method of unbalanced costs caused by agency power purchases clearly reveals the unbalanced cost-sharing mechanism in the context of the unified spot.

Experimental investigation on magnetic field strength providing thrust saturation in a magnetic nozzle radiofrequency plasma thruster

Magnetic field strength applied to a magnetic nozzle radiofrequency (rf) plasma thruster having a 10.5 cm diameter source tube is increased up to about 3 kG by pulsing the solenoid current. A target plate is installed at 30 cm downstream of the source and an impulse bit exerted to the target is measured to assess the thrust, where the thrust balance measurement was impossible due to the interaction between the pulsed magnetic fields and the eddy currents on surroundings. Since the diameter of the plasma plume at the target location is larger than the target diameter, a comparison between the thrust balance and target measurements under continuous magnetic field and rf power is performed prior to the pulsed magnetic field experiments, showing that about 65 percent of the plasma momentum is exerted to the target plate. Saturation of the impulse bit, being equivalent to the force multiplied by the rf pulse width, is clearly observed when increasing the magnetic field strength. The magnetic field providing the force saturation is found to be changed by the source diameter, which is qualitatively explained by considering a change in the plasma loss to the source wall in a thruster model containing the particle balance, power balance, and one-dimensional magnetic nozzle models. It is suggested that the magnetic field strength required for optimizing the force, i.e. the thrust, can be reduced when enlarging the source tube diameter.

An open-source power balance model for the estimation of tokamak net electrical power output

One of the largest hurdles for commercialisation of magnetic confinement fusion has historically been achieving net power — existing experiments require more electricity to keep the tokamak running than it could theoretically generate, and none have been equipped with thermal to electric conversion equipment. When designing a machine that intends to overcome this, there must be a cheap and robust way for the designer to estimate what the net power will be, preferably with the ability to perform parametric sweeps, without having to know the detailed design of each system. The work presented in this paper is an integrated time-dependent model, describing the power demands of the major tokamak components (magnets, cryogenics, heating and current drive, etc.), as well as the power generated, with a focus on the steady-state operation. The physics are implemented in OpenModelica and make use of a Python API (Application Programming Interface) to collect inputs, run studies and record outputs. The model cannot be validated against real world data, since there is no operational tokamak in the world designed for electrical power generation. Therefore, the correctness of each submodule (i.e., the magnet model, the cryogenics model) has been validated either from first principles or via validation against data from JET (Joint European Torus) where possible. The model has been used extensively as part of the work on the UK’s Spherical Tokamak for Energy Production (STEP) and has informed decisions on the STEP concept. It is publicly available on GitHub.

Use of Sound "PHONONS' in the modelling and Optimisation of automotive acoustic systems in 3D

Automotive manufacturers demand components with an ever higher acoustic performance combined with lower environmental impact, tuned to the emerging EV market, and are pressured into reducing lead times and prototype investment. Consequently, there is a desire for enhanced simulation techniques, utilizing advanced methods. The three-dimensional aspect of many palliative treatments can be shown to afford significant benefits to their acoustic performance, both in their transmission loss and random incidence absorption characteristics. Virtual system engineering enables construction fundamentals to be created in CAD, but often acoustic treatments are chosen based on flat sample performance or simple power balance models. These do not tell the complete story. Current acoustic simulation techniques such as SEA, may present the model in a 3D environment to aid in visualization but, solving is done on a 2D matrix basis, and does not account easily for diffusion and refractive interaction caused by the complex shape of the component under investigation. BEM and FEM techniques are 3D based simulations but have a host of limitations due to mesh density and available processing power. Constructing models of individual palliatives such as wheel arch liners, dash insulations or carpets using such techniques may be of academic interest but of restricted use in the pressured world of component design and manufacture. It is not helped by the need to furnish the model with accurate, validated, material performance data. A modelling procedure was required that could import component CAD from the product design team and rapidly create an acoustic model that could accurately predict its performance in both a transmission loss suite and associated random incidence "Alpha cabin" absorption test. Thus, short circuit the need for at least one if not more prototype test phases or enable quotations for new business to be formulated with a higher degree of clarity. Subsequently to export results from this model into a range of "full vehicle" modelling environments or compare to prototype test results. After considerable research the authors created and validated a toolbox approach using a combination of open-source code together with bespoke modifications and defined processing procedures.

Modelling of ohmic startup and runaway electron formation in support of JT-60SA initial operation

The plasma startup with ITER-relevant sub-mPa neutral pressures in the JT-60SA superconducting tokamak is studied using a zero-dimensional (0D) power balance model for the plasma burn-through phase. In the ohmic startup scenario assumed here, the lower limit of the operational neutral pressure is determined by the condition for the Townsend avalanche at a high limit, whereas the upper limit depends on the available ohmic heating power for the burn-through with the base power supply (PS) of the superconducting coils, corresponding to 0.2–0.3 V m−1. The operational conditions that lead to RE generation are evaluated to mitigate the risk of RE discharges. The simulation shows that startup REs are generated during the temperature rise immediately after the burn-through under relatively low-density conditions, and then the RE current value is gradually increased in balance with the RE loss processes on the timescale of I p ramp-up. Therefore, it is expected that REs can be avoided or mitigated if the electron density during the early build-up phase is tuned by a combination of prefill gas and additional fuelling. However, a startup with an excessive prefill gas will lose the margin of the density control, and a full RE discharge can be triggered when the plasma burn-through fails owing to a high concentration of impurities such as oxygen, if the operational point is marginal to the burn-through limit. The present modelling work implies that preparing the operation with sufficient margins against the failure of impurity burn-through is important for mitigating the risk of unintended plasma termination. Although the carbon wall environment may have a lower risk of RE generation, to alleviate the operational uncertainties of the new device, strategies for expanding the operational window are also discussed in support of JT-60SA initial operation.

Improving the feasibility of economical proton-boron-11 fusion via alpha channeling with a hybrid fast and thermal proton scheme.

The proton-boron-11 (p-B11) fusion reaction is much harder to harness for commercial power than the easiest fusion reaction, namely, the deuterium and tritium (DT) reaction. The p-B11 reaction requires much higher temperatures, and, even at those higher temperatures, the cross sectionis much smaller. However, as opposed to tritium, the reactants are both abundant and nonradioactive. It is also an aneutronic reaction, thus avoiding radioactivity-inducing neutrons. Economical fusion can only result, however, if the plasma is nearly ignited; in other words if the fusion power is at least nearly equal to the power lost due to radiation and thermal conduction. Because the required temperatures are so high, ignition is thought barely possible for p-B11, with fusion power exceeding the bremsstrahlung power by only around 3%. We show that there is a high upside to changing the natural flow of power in the reactor, putting more power into protons, and less into the electrons. This redirection can be done using waves, which tap the alpha particle power and redirect it into protons through alpha channeling. Using a simple power balance model, we show that such channeling could reduce the required energy confinement time for ignition by a factor of 2.6 when energy is channeled into thermal protons, and a factor of 6.9 when channeled into fast protons near the peak of the reactivity. Thus, alpha channeling could dramatically improve the feasibility of economical p-B11 fusion energy.

Multi-Objective Design Optimization of Cusped Field Thruster via Surrogate-Assisted Evolutionary Algorithms

Cusped field thrusters are an efficient cost-effective electric propulsion technology that offer promise for small spacecraft platforms. They offer various advantages, including simple design and low wall erosion, and hence long-life operation owing to high plasma confinement using permanent magnets over other electrostatic alternatives. Accurate physical modeling and performance characterization are crucial to achieve successful downscaling of cusped field thrusters while maintaining high performance. Multiobjective design optimization is performed by incorporating magnetic simulation coupled with an improved power balance model into evolutionary algorithms assisted by surrogate modeling, aiming to simultaneously maximize thrust, total efficiency, and specific impulse. Physical insights have been gained into key design factors to maximize thruster performance by probing into the plasma behavior inside the channel and the plume region. It has been found that altering the magnetic field distribution using an additional magnet can effectively enhance thruster performance by suppressing the plume divergence loss. Global sensitivity analysis has identified the anode current as the most influential design parameter on the performance parameters due to the active role it plays in the ionization process. Uncertainty analysis has found the considerable influence of the variations of anode potential and mass flow rate on those of thrust and specific impulse.

Power output and energy cost: crucial measures to understand motor skill learning in handrim wheelchair propulsion

BACKGROUND: This current opinion is a call for standardization of measurements of manual wheeling ability among larger and diverse populations to support our understanding of motor control and learning. VIEW OF THE PAST: Handrim wheelchair propulsion remains the most common mode of wheeled ambulation and has stood the test of time as a practical upper-body alternative to walking. CURRENT STATE: Two theoretical models appeared useful in understanding the demands on the wheelchair-user combination and the role of motor skill acquisition: Power Balance Model and Constraint-based Approach. FUTURE PERSPECTIVE: Power output and energy cost measures are crucial mediators in the development of a motor control theory of cyclic motions in rehabilitation, adapted sports and beyond.

Experimental investigation of high velocity neutral flow interaction with a magnetized plasma

Plasma aerocapture is an orbit insertion method that leverages a magnetic dipole plasma to generate drag by ionizing, capturing, and deflecting atmospheric flow. Key physical assumptions about energy and momentum exchange during aerocapture are tested here by a novel experiment that characterizes the interaction between a high velocity free molecular flow and a magnetized plasma. A neutral beam source accelerates ions from a helicon plasma to a conductive plate, neutralizes them, and reflects them as a collimated flow. A hollow cathode plasma with an applied axial magnetic field of 1 kg acts as the target for the flow. It is found that interaction with the flow causes an increase in both density and temperature of the target plasma by up to a factor of two. The voltage required to operate the hollow cathode at a fixed current is reduced by up to 5% while the neutral beam is operating, suggesting power deposition by the flow. A 0D power balance model is invoked to show that flow kinetic energy is absorbed by the plasma at a rate of up to 50% of the hollow cathode power. The absorbed power correlates linearly with an electron temperature increase of up to 100%, indicative of electron heating by flow kinetic energy transfer. Deflection of the flow by the plasma is not resolved due to extraneous forces on the measurement device and uncertainties in plasma properties. Using the results found here, it is shown that the experiment can feasibly scale to demonstrate significantly higher energy and momentum transfer as required for a plasma aerocapture proof-of-concept.

A power-balance model for the L-mode radiative density limit in fusion plasmas

A 1D cylindrical power-balance model of the radiation density limit (DL) gives a unified description of this phenomenon for stellarators, reversed field pinches and L-mode tokamaks (Zanca et al 2019 Nucl. Fusion 59 126011). The DL scaling laws for the three different configurations are all derived from a combination of just two equations: (a) a single-fluid heat-transport equation; (b) on-axis Ohm’s law with Spitzer resistivity, taken in a suitable limit for the stellarator. Here, we present a refined version of the model, alongside further experimental evidence supporting its successful application.

Efficient Lasing Through Raman-Assisted Four-Wave Mixing With Intrinsic Weak Spectral Broadening Characteristics

Narrow linewidth nonlinear frequency conversion has attracted numerous research attentions. In this manuscript, we demonstrate efficient frequency conversion with weak spectral broadening characteristics through Raman-assisted four-wave mixing (FWM) process in birefringent phosphosilicate fiber. The output power of the generated Stokes light reaches 12.05 W, with a conversion efficiency of 67.4%. Compared to previously reported FWM-based fiber lasers with output power and conversion efficiency below watt level and 50% respectively, our result shows significant improvement. Besides, benefiting from the strict phase match requirement of FWM process, this laser system has unique advantages in suppressing spectral broadening, the output linewidth of which is less than half of the conventional Raman fiber laser under same power level. Furtherly, we propose a power balance model to describe the power evolution characteristics of the Raman-assisted FWM process, proving the advantage of phosphosilicate fiber in improving the conversion efficiency of FWM process. This work gives a reference for efficient narrow linewidth frequency conversion or amplification.

User-transformer relation identification based on power balance model and adaptive AFSA

User-transformer relation identification plays an important role in the correct management of low-voltage area archives and the improvement of line loss. In order to obtain an accurate user-transformer relation identification, this paper proposes a user-transformer relation identification method in the low-voltage area based on power balance model and adaptive artificial fish swarm algorithm(AFSA). This method uses the summation relationship between the total meter of the transformer and the user’s meter/meter box to fit the coefficients of the power balance equation through the AFSA, then we use the coefficients and related statistical values to judge the user-transformer relation. The main innovations are: this paper proposes a power balance model to solve the problem of user-transformer relation identification, which is simpler than previous methods and has strong operability; AFSA is used to fit the regression coefficients of the power balance equation, which has advantages in calculation accuracy and efficiency compared with the traditional least squares method; an improvement strategy of adaptive step length is proposed to make the ability of AFSA to find superior stronger. By selecting real station data for verification, the result shows that the method in this paper can quickly and accurately identify user’s meters/meter boxes with abnormal user-transformer relationship, the method in this paper has high computational efficiency and recognition accuracy without additional labor and hardware costs.

An Active Voltage Coordinate Control Strategy of DFIG-Based Wind Farm with Hybrid Energy Storage System

In a power system with wind farms, the point of common coupling (PCC) usually suffers from voltage instability under large wind speed variations and the load impact. Using the internal converter of a doubly fed induction generator (DFIG)-based wind turbine to provide voltage support auxiliary service is an effective scheme to suppress the voltage fluctuation at PCC. To satisfy the reactive power demand of the connected grid, an active voltage coordinate control strategy with the hybrid energy storage system of the wind farm is proposed. The dynamic reactive power balance model is established to show the interaction between the reactive power limitation of the wind farm and the reactive power compensation demand of the grid. This indicates the initial conditions of the active voltage coordinate control strategy. According to the critical operating point and the operation state of the DFIG, the active and reactive power coordinate control strategy composed of active ω-β coordinate control and active β control is proposed to enhance the reactive power support capability and stabilize the grid voltage. To compensate the active power shortage, an auxiliary control strategy based on the hybrid energy storage system is introduced. The simulation results show that the proposed strategy can suppress the voltage fluctuation effectively and make full use of primary energy.

Research On Energy Distribution of Multi-Scene Hydropower System Through Improved Power Load Optimization Strategy

Taking the minimization of coal consumption in hydro-thermal power system as the objective function, this paper focuses on the static water abandonment strategy and improved dynamic water abandonment strategy, given the constraint conditions of hydropower station generation flow, reservoir water quantity, load balance constraint and power constraint. in this paper, the penalty cost of abandoned water is introduced into the existing model, and a short-term electric power balance model considering the cost of abandoned water is established. In view of the deficiency that it is difficult to effectively obtain feasible solutions that meet large-scale and complex constraints in the process of solving the model, the premature convergence and local optimization of the algorithm are avoided. An optimization algorithm is proposed to provide reference for solving the problem that the calculation efficiency of optimal dispatching of large-scale hydropower stations is the problem faced by hydropower and power system operation.

A locational Marginal Price-Based Partition Optimal Economic Dispatch Model of Multi-Energy Systems

The large-scale penetration of renewable energy and deeply integrated multiple energy forms pose a major challenge for the accounting and allocation process of additional adjustment cost in multi-energy system and electricity market. The variable wind power and the operating status of multi-energy systems faced by the electricity market have driven researchers towards the decision of electricity spot market with complicated pricing mechanism. This paper presents a locational marginal price-based partition optimal economic dispatch model of multi-energy system with a high proportion of renewable energy. First, a model of the additional adjustment cost of multi-energy adjustable units to improve the power grid adjustment capacity is studied based on the power balance model of multi-energy conversion and storage. In the second, to improve the effectiveness of the ESM mechanism, an optimal economic dispatch model is established, with the goal of minimizing the additional adjustment cost of multi-energy adjustable units. Moreover, according to the characteristics of the model and the mechanism of locational marginal price-based economic dispatch, a solution method based on lagrangian relaxation is proposed. The incentive compatible locational marginal price is obtained. Finally, a simulation model of multi-energy systems based on IEEE 39-nodes power system and 7-nodes natural gas system is established. And the model is based on operating data of an actual grid with high proportion of renewable energy in Northeast China. The results of the examples show that the proposed method can effectively improve the efficiency and flexibility of multi-energy system. Another advantage of the proposed method is that the capabilities of the complementary multi-energy coordination can be promoted.

Ion heating in the PISCES-RF liquid-cooled high-power, steady-state, helicon plasma device

Radio frequency (RF) driven helicon plasma sources are commonly used for their ability to produce high-density argon plasmas (n > 1019 m−3) at relatively moderate powers (typical RF power < 2 kW). Typical electron temperatures are <10 eV and typical ion temperatures are <0.6 eV. A newly designed helicon antenna assembly (with concentric, double-layered, fully liquid-cooled RF-transparent windows) operates in steady-state at RF powers up to 10 kW. We report on the dependence of argon plasma density, electron temperature and ion temperature on RF power. At 10 kW, ion temperatures >2 eV in argon plasmas are measured with laser induced fluorescence, which is consistent with a simple volume averaged 0D power balance model. 1D Monte Carlo simulations of the neutral density profile for these plasma conditions show strong neutral depletion near the core and predict neutral temperatures well above room temperatures. The plasmas created in this high-power helicon source (when light ions are employed) are ideally suited for fusion divertor plasma-material interaction studies and negative ion production for neutral beams.