Synergetic optimization operation method for distribution network based on SOP and PV

The integration of distributed generation brings in new challenges for the operation of distribution networks,including out-of-limit voltage and power flow control.Soft open points(SOP)are new power electronic devices that can flexibly control active and reactive power flows.With the exception of active power output,photovoltaic(PV)devices can provide reactive power compensation through an inverter.Thus,a synergetic optimization operation method for SOP and PV in a distribution network is proposed.A synergetic optimization model was developed.The voltage deviation,network loss,and ratio of photovoltaic abandonment were selected as the objective functions.The PV model was improved by considering the three reactive power output modes of the PV inverter.Both the load fluctuation and loss of the SOP were considered.Three multi-objective optimization algorithms were used,and a compromise optimal solution was calculated.Case studies were conducted using an IEEE 33-node system.The simulation results indicated that the SOP and PVs complemented each other in terms of active power transmission and reactive power compensation.Synergetic optimization improves power control capability and flexibility,providing better power quality and PV consumption rate.

Optimal Scheduling for Flexible Regional Integrated Energy Systemwith Soft Open Point

The Regional Integrated Energy System(RIES)has brought new modes of development,utilization,conversion,storage of energy.The introduction of Soft Open Point(SOP)and the application of Power to Gas(P2G)technology will greatly deepen the coupling of the electricity-gas integrated energy system,improve the flexibility and safety of the operation of the power system,and bring a deal of benefits to the power system.On this background,an optimal dispatch model of RIES combined cold,heat,gas and electricity with SOP is proposed.Firstly,RIES architecture with SOP and P2G is designed and its mathematical model also is built.Secondly,on the basis of considering the optimal scheduling of combined cold,heat,gas and electricity,the optimal scheduling model for RIES was established.After that,the original model is transformed into a mixed-integer second-order cone programming model by using linearization and second-order cone relaxation techniques,and the CPLEX solver is invoked to solve the optimization problem.Finally,the modified IEEE 33-bus systemis used to analyze the benefits of SOP,P2G technology and lithium bromide absorption chillers in reducing systemnetwork loss and cost,as well as improving the system’s ability to absorb wind and solar and operating safety.

TREATMENT OF SOFT TISSUE INJURY BY PUNCTURING CLEFT-POINTS

Objective: To observe the therapeutic effect of acupuncture of "Xi" (Cleft) points in treatment of soft tissue injury. Methods: 335 cases of soft tissue injury patients were divided into Cleft point group (264 cases) and Ashi point group (control group, 71 cases) randomly. In Cleft point group, the 16 Cleft points were used in combination with Ahshi points. In control group, only local Ahshi points were punctured. The treatment was conducted once every day, with 5 sessions being a therapeutic course. After 2 courses of treatment, the therapeutic effect was analyzed. Results: Results showed that the therapeutic effect of cleft point group was significantly better than that of control group (P<0.05), particularly in treatment of acute soft tissue. Conclusion: Cleft point acupuncture has a better therapeutic effect in treatment of soft tissue injury in comparison with Ashi point.

Laboratory investigation of axisymmetric single vacuum well point

Vacuum well point is a new but faint soft ground treatment method. This work focuses on the consolidation behavior of a reconstituted soft clayey specimen under vacuum well point combined with surcharge loading. The laboratory test was conducted through a vacuum-surcharge consolidation apparatus, and the vacuum loading scheme was adopted for vacuum pressure application to investigate the vacuum effect on soil consolidation. In the testing process, some key parameters such as vacuum pressure, pore water pressure and settlement deformation were timely recorded. Furthermore, the water content, void ratio and permeability coefficient of samples collected after loading were measured to reflect the consolidation characteristics. By comparing with the membrane system and membraneless system, something different was found for the vacuum well point method. The results indicate that the consolidation behavior of an axisymmetric single vacuum well point is almost identical to the behavior of vacuum preloading combined with prefabricated vertical drain(PVD), except for the distribution of the vacuum pressure along the well drain due to the structure of the vacuum well point. And the vacuum well point method may be useful for the improvement of soft clayey deposit in a certain depth.

Multi-source coordinated stochastic restoration for SOP in distribution networks with a two-stage algorithm

After suffering from a grid blackout, distributed energy resources(DERs), such as local renewable energy and controllable distributed generators and energy storage can be used to restore loads enhancing the system’s resilience. In this study, a multi-source coordinated load restoration strategy was investigated for a distribution network with soft open points(SOPs). Here, the flexible regulation ability of the SOPs is fully utilized to improve the load restoration level while mitigating voltage deviations. Owing to the uncertainty, a scenario-based stochastic optimization approach was employed,and the load restoration problem was formulated as a mixed-integer nonlinear programming model. A computationally efficient solution algorithm was developed for the model using convex relaxation and linearization methods. The algorithm is organized into a two-stage structure, in which the energy storage system is dispatched in the first stage by solving a relaxed convex problem. In the second stage, an integer programming problem is calculated to acquire the outputs of both SOPs and power resources. A numerical test was conducted on both IEEE 33-bus and IEEE 123-bus systems to validate the effectiveness of the proposed strategy.

Soft Locally Compact Spaces and Soft Paracompact Spaces

The concept of soft topological space was introduced by some authors. In the present paper, we investigate some basic notions of soft topological spaces by using new soft point concept. Later we give soft locally compact space and the relationships between them are discussed in detail. Finally, we define soft paracompactness and explore some of its basic properties.

Two-stage Optimization for Active Distribution Systems Based on Operating Ranges of Soft Open Points and Energy Storage System

Due to the lack of flexible interconnection devices,power imbalances between networks cannot be relieved effectively.Meanwhile,increasing the penetration of distributed generators exacerbates the temporal power imbalances caused by large peak-valley load differences.To improve the operational economy lowered by spatiotemporal power imbalances,this paper proposes a two-stage optimization strategy for active distribution networks(ADNs)interconnected by soft open points(SOPs).The SOPs and energy storage system(ESS)are adopted to transfer power spatially and temporally,respectively.In the day-ahead scheduling stage,massive stochastic scenarios against the uncertainty of wind turbine output are generated first.To improve computational efficiency in massive stochastic scenarios,an equivalent model between networks considering sensitivities of node power to node voltage and branch current is established.The introduction of sensitivities prevents violations of voltage and current.Then,the operating ranges(ORs)of the active power of SOPs and the state of charge(SOC)of ESS are obtained from models between networks and within the networks,respectively.In the intraday corrective control stage,based on day-ahead ORs,a receding-horizon model that minimizes the purchase cost of electricity and voltage deviations is established hour by hour.Case studies on two modified ADNs show that the proposed strategy achieves spatiotemporal power balance with lower cost compared with traditional strategies.

Soft Open Point Planning in Renewable-dominated Distribution Grids with Building Thermal Storage

With an increasing integration of intermittent distributed energy resources(DERs),the consequent voltage excursion and thermal overloading issues limit the self-sufficiency of distribution networks(DNs).The concept of soft open point(SOP)has been proposed as a promising solution to improve the hosting capacity of DNs.In this paper,considering the ability of building thermal storage(BTS)to increase the penetration of renewable energy in DNs,we provide an optimal planning framework for SOP and DER.The optimal planning model is aimed at minimizing the investment and operational costs while respecting various constraints,including the self-sufficiency requirement of the DN,SOP,building thermal storage capacity and DER operations,etc.A steady-state SOP model is formulated and linearized to be incorporated into the planning framework.To make full use of the BTS flexibility provided by ubiquitous buildings,a differential equation model for building thermal dynamics is formulated.A hybrid stochastic/robust optimization approach is adopted to depict the uncertainties in renewable energy and market prices.IEEE 33-bus feeder and a realistic DN in the metropolitan area of Caracas are tested to validate the effectiveness of the proposed framework and method.Case studies show that SOP/BTS plays a complementary and coordinated coupling role in the thermo-electric system,thereby effectively improving the hosting capacity and self-sufficiency of DNs.

Successive MISOCP Algorithm for Islanded Distribution Networks with Soft Open Points

An optimal operation scheme is of great significance in islanded distribution networks to restore critical loads and has recently attracted considerable attention.In this paper,an optimal power flow(OPF)model for islanded distribution networks equipped with soft open points(SOPs)is proposed.Unlike in the grid-connected mode,the adequacy of local power generation in distribution networks is critical for islanded systems.The proposed approach utilizes the power output of local distributed generations(DGs)and the benefits of reactive power compensation provided by SOPs to allow maximum loadability.To exploit the available resources,an optimal secondary droop control strategy is introduced for the islanded distribution networks,thereby minimizing load shedding.The formulated OPF problem is essentially a mixed-integer nonlinear programming(MINLP)model.To guarantee the computation efficiency and accuracy.A successive mixed-integer second-order cone programming(SMISOCP)algorithm is proposed for handling the nonlinear islanded power flow formulations.Two case studies,incorporating a modified IEEE 33-bus system and IEEE 123-bus system,are performed to test the effectiveness of the proposed approach.

A New Approach to Vague Soft Bi-Topological Spaces

Fuzzy soft topology considers only membership value.It has nothing to do with the non-membership value.So an extension was needed in this direction.Vague soft topology addresses bothmembership and non-membership values simultaneously.Sometimes vague soft topology(single structure)is unable to address some complex structures.So an extension to vague soft bi-topology(double structure)was needed in this direction.To make this situation more meaningful,a new concept of vague soft bi-topological space is introduced and its structural characteristics are attempted with a new definition.In this article,new concept of vague soft bi-topological space(VSBTS)is initiated and its structural behaviors are attempted.This approach is based on generalized vague soft open sets,known as vague softβopen sets.An ample of examples are given to understand the structures.For the non-validity of some results,counter examples are provided to pay the price.Pair-wise vague softβopen and pair-wise vague softβclose sets are alsoaddressedwith examples in(VSBTS).Vague soft separation axioms are initiatedin(VSBTS)concerning soft points of the space.Other separation axioms are also addressed relative to soft points of the space.Vague soft bi-topological properties are studied with the application of vague softβopen sets with respect to soft points of the spaces.The characterization of vague softβclose as well as vague softβopen sets,characteristics of Bolzano Weirstrass property,vague soft compactness and its marriage with sequences,interconnection between sequential compactness and countable compactness in(VSBTS)with respect to softβopen sets are addressed.

A New Attempt to Neutrosophic Soft Bi-Topological Spaces

In this article,new generalized neutrosophic soft∗b open set is introduced in neutrosophic soft bi-topological structurers(NSBTS)concerning soft points of the space.This new set is produced by making the marriage of soft semi-open set with soft pre-open set in neutrosophic soft topological structure.An ample of results are investigated in NSBTS on the basis of this new neutrosophic soft∗b open set.Proper examples are settled for justification of these results.The non-validity of some results is vindicated with examples.

The Soft Point and Its Applications in Body Falling

From the mesoscopic point of view,a definition of soft point is introduced by considering the attributes of geometric profile and mass distribution.After that,this concept is used to develop the soft matching technique to simulate the chaotic behaviors of the equations.Especially,a tennis model with deformation factor a(t)is proposed to derive a generalized Newton-Stokes equation v′(t)=λ(v T-a(t)v(t)).Furthermore,a concept of duality of deformation factor a(t)and velocity v(t)with respect to the generalized NewtonStokes equation is established.To solve this equation,two data-driven models of a(t)are provided,one is based on the concept of soft matching,while the other is by using the amplitude modulation.Finally,the related iterative algorithm is developed to simulate the motion of the falling body via the duality of a(t)and v(t).Numerical examples successfully demonstrate the phenomenon of chaos,which consists of the continual random oscillations and sudden accelerations.Moreover,the algorithm is tested by using larger coefficients corresponding to the terminal velocity and shows more satisfactory results.It may enable us to characterize the total energy of the dynamical system more accurately.

Reconfiguration of Active Distribution Networks Equipped with Soft Open Points Considering Protection Constraints

The purpose of active distribution networks(ADNs)is to provide effective control approaches for enhancing the operation of distribution networks(DNs)and greater accommodation of distributed generation(DG)sources.With the integration of DG sources into DNs,several operational problems have drawn attention such as overvoltage and power flow alteration issues.These problems can be dealt with by utilizing distribution network reconfiguration(DNR)and soft open points(SOPs).An SOP is a power electronic device capable of accurately controlling active and reactive power flows.Another significant aspect often overlooked is the coordination of protection devices needed to keep the network safe from damage.When implementing DNR and SOPs in real DNs,protection constraints must be considered.This paper presents an ADN reconfiguration approach that includes DG sources,SOPs,and protection devices.This approach selects the ideal configuration,DG output,and SOP placement and control by employing particle swarm optimization(PSO)to minimize power loss while ensuring the correct operation of protection devices under normal and fault conditions.The proposed approach explicitly formulates constraints on network operation,protection coordination,DG size,and SOP size.Finally,the proposed approach is evaluated using the standard IEEE 33-bus and IEEE 69-bus networks to demonstrate the validity.

Multi-stage Coordinated Robust Optimization for Soft Open Point Allocation in Active Distribution Networks with PV

To optimize the placement of soft open points(SOPs)in active distribution networks(ADNs),many aspects should be considered,including the adjustment of transmission power,integration of distributed generations(DGs),coordination with conventional control methods,and maintenance of economic costs.To address this multi-objective planning problem,this study proposes a multi-stage coordinated robust optimization model for the SOP allocation in ADNs with photovoltaic(PV).First,two robust technical indices based on a robustness index are proposed to evaluate the operation conditions and robust optimality of the solutions.Second,the proposed coordinated allocation model aims to optimize the total cost,robust voltage offset index,robust utilization index,and voltage collapse proximity index.Third,the optimization methods of the multiand single-objective models are coordinated to solve the proposed multi-stage problem.Finally,the proposed model is implemented on an IEEE 33-node distribution system to verify its effectiveness.Numerical results show that the proposed index can better reveal voltage offset conditions as well as the SOP utilization,and the proposed model outperforms conventional ones in terms of robustness of placement plans and total cost.

Voltage Unbalance Compensation in Distribution Feeders Using Soft Open Points

Soft open points(SOPs)are power electronic devices that may replace conventional normally-open points in distribution networks.They can be used for active power flow control,reactive power compensation,fault isolation,and service restoration through network reconfiguration with enhanced operation flexibility and grid resiliency.Due to unbalanced loading conditions,the voltage unbalance issue,as a common problem in distribution networks,has negative impacts on distribution network operation.In this paper,a control strategy of voltage unbalance compensation for feeders using SOPs is proposed.With the power flow control,three-phase current is regulated simultaneously to mitigate the unbalanced voltage between neighboring feeders where SOPs are installed.Feeder voltage unbalance and current unbalance among three phases are compensated with the injection of negative-sequence and zero-sequence current from SOPs.Especially in response to power outages,three-phase voltage of isolated loads is regulated to be balanced by the control of SOPs connected to the feeders under faults,even if the loads are unbalanced.A MATLAB/Simulink model of the IEEE 13-bus test feeder with an SOP across feeder ends is implemented,and experimental tests on a hardware-in-the-loop platform are implemented to validate the effectiveness of the proposed control strategy.

Multi-stage expansion planning of energy storage integrated soft open points considering tie-line reconstruction

With the rapid development of flexible interconnection technology in active distribution networks(ADNs),many power electronic devices have been employed to improve system operational performance.As a novel fully-con-trolled power electronic device,energy storage integrated soft open point(ESOP)is gradually replacing traditional switches.This can significantly enhance the controllability of ADNs.To facilitate the utilization of ESOP,device loca-tions and capacities should be configured optimally.Thus,this paper proposes a multi-stage expansion planning method of ESOP with the consideration of tie-line reconstruction.First,based on multi-terminal modular design characteristics,the ESOP planning model is established.A multi-stage planning framework of ESOP is then presented,in which the evolutionary relationship among different planning schemes is analyzed.Based on this framework,a multi-stage planning method of ESOP with consideration of tie-line reconstruction is subsequently proposed.Finally,case studies are conducted on a modified practical distribution network,and the cost-benefit analysis of device and multiple impact factors are given to prove the effectiveness of the proposed method.

Control Strategy for DC Soft Open Points in Large-scale Distribution Networks with Distributed Generators

Development of power electronic devices and their implementation in power distribution networks significantly improves not only the easier integration of distributed generation into distribution networks but also the further refinement of control algorithms specialized in the application of power management procedures in distribution systems.Implementation of DC Soft Open Points(DCSOP)for closing loops in distribution networks could serve as one of the most representative examples of the use of power electronic devices as management resources in modern distribution networks.The paper describes the possibilities of the application of DCSOP used for loops closure and power flow control in medium voltage distribution networks with integrated distributed generators.Considering all the benefits of loops closure and the controllability of the DCSOP,it is considered as a management resource capable of achieving the desired/optimal state in the distribution network.The management strategy proposed in this paper covers two cases:the first case is where an adequate communication infrastructure is available when all DCSOP operations are based on Optimal Power Flow(OPF)calculations,and the second case is when OPF results are unavailable for some reason(most often due to communication interruptions)and DCSOP operations are based on processing available data using a neural network-based algorithm.The proposed management strategy has been implemented and tested on an IEEE 33 distribution test network with integrated distributed generators.The simulation results,described in this paper,can serve not only as a basis for further scientific research but also as a basis for the practical implementation of real controllers based on the proposed algorithm and its application in practice,and in real distribution networks.