Methods for measuring and calculating the external load of powered supports

Taking the chock shield supports as the object of study, methods formeasuring and calculating the external load of powered supports were discussed. Selecting the angleparameters as variables, the simple formulae of interactive computation with respect to the workangles of a powered support were deduced and verified by an example. Furthermore, the formulaedetermining the magnitude, direction and action point of the external load were put forward. Theinvestigation results have provided a sound basis for the software design of the intelligentinstrument for load measuring of powered supports.

A multi-energy inertia-based power support strategy with gas network constraints

An integrated energy system with multiple types of energy can support power shortages caused by the uncertainty of renewable energy.With full consideration of gas network constraints,this paper proposes a multi-energy inertia-based power support strategy.The definition and modelling of gas inertia are given first to demonstrate its ability to mitigate power fluctuations.Since partial utilization of gas inertia can influence overall gas network parameters,the gas network is modelled with an analysis of network dynamic changes.A multi-energy inertia-based power support model and strategy are then proposed for fully using gas-thermal inertia resources in integrated energy systems.The influence of gas network constraints on strategy,economy and power outputs is analyzed.Special circumstances where the gas network can be simplified are introduced.This improves the response speed and application value.The feasibility and effectiveness of the proposed strategy are assessed using a real scenario.

Secondary Frequency Control Considering Optimized Power Support From Virtual Power Plant Containing Aluminum Smelter Loads Through VSC-HVDC Link

The growing number of renewable energy replacing conventional generators results in a loss of the reserve for frequency control in power systems,while many industrial power grids often have excess energy supply due to abundant wind and solar energy resources.This paper proposes a secondary frequency control(SFC)strategy that allows industrial power grids to provide emergency high-voltage direct current(HVDC)power support(EDCPS)for emergency to a system requiring power support through a voltage source converter(VSC)HVDC link.An architecture including multiple model predictive control(MPC)controllers with periodic communication is designed to simultaneously obtain optimized EDCPS capacity and minimize adverse effects on the providing power support(PPS)system.Moreover,a model of a virtual power plant(VPP)containing aluminum smelter loads(ASLs)and a high penetration of wind power is established for the PPS system.The flexibility and controllability of the VPP are improved by the demand response of the ASLs.The uncertainty associated with wind power is considered by chance constraints.The effectiveness of the proposed strategy is verified by simulation results using the data of an actual industrial power grid in Inner Mongolia,China.The DC voltage of the VSCs and the DC in the potlines of the ASLs are also investigated in the simulation.

A Unified Control of Super-capacitor System Based on Bi-directional DC-DC Converter for Power Smoothing in DC Microgrid

To improve the equivalent inertia of DC microgrids(DCMGs),a unified control is proposed for the first time for a bi-directional DC-DC converter based super-capacitor(SC)system,whereby power smoothing and SC terminal voltage regulation can be achieved in a DCMG simultaneously.The proposed control displays good plug-and-play features using only local measurements.For quantitative analysis and effective design of the critical parameter of unified control,two indices,equivalent power supporting time and inertia contributed by the unified controlled SC system,are introduced firstly.Then,with a simple but effective reduced-order model of a DCMG,analytical solutions are obtained for the two indices.In addition,a systematic design method is presented for the proposed unified control.Finally,to verify the proposed unified control,a switching model is developed for a typical DCMG in PSCAD/EMTDC,and theoretical analyses are conducted for different operating conditions.

Coordinated Modulation Strategy Considering Multi-HVDC Emergency for Enhancing Transient Stability of Hybrid AC/DC Power Systems

This paper presents a multi-HVDC emergency coordinated modulating strategy to enhance the transient stability of hybrid AC/DC power systems.First,the main factors that affect the unbalanced energy distribution during a fault are analyzed,and the dominant generators are determined online.Next,considering the influence on both generators in the sending and receiving ends,the assessment index that evaluates the effects of DC power support is established.On the basis of this,a dynamic DC power support strategy is put forward,and the DC support sequence table is promptly updated by the changing dominant generators.The AC/DC hybrid power system with multi-DC lines is built and used as a test system.The simulation results of different scenarios demonstrate that the proposed method could follow the dominant generator dynamically and adjust the DC participating in modulation to enhance the transient stability effectively and quickly.