Proposed Coordination Approach Research Articles

Innovative Adaptive Protection Approach to Maximize the Security and Performance of Phase/Earth Overcurrent Relay for Microgrid Considering Earth Fault Scenarios.

Microgrids are increasingly paying attention to the emerging of distributed energy resources. However, microgrid protection has challenged engineers because of the varying nature of fault current distribution during grid-connected and islanded operations. This paper suggests a novel approach of coordination between phase and earth fault overcurrent relays to ensure stability and security for the performance of protection schemes in active distribution networks. In this study, a combination of phase and earth overcurrent relays is coordinated to avoid mis-coordination in the overcurrent protection schemes. In the proposed approach, phase overcurrent function was employed as backup protection for earth fault function locally in the same relay instead of the traditional remote backup earth fault protection coordination approach. The suggested coordination approach provides a fast and reliable protection performance in different earth faults scenarios. The coordination was tested on the IEC Microgrid Benchmark network. Also, the objective function was modified to reduce the overall operational time using two recently developed metaheuristic optimization algorithms known as the charged system search (CSS) and Teaching-Learning-Based Optimization Algorithm (TLBO) in the MATLAB package. Finally, the time multipler setting values were adapted and compared to verify the speed and reliability of the proposed coordination approach using ETAP.

Highly Fast Innovative Overcurrent Protection Scheme for Microgrid Using Metaheuristic Optimization Algorithms and Nonstandard Tripping Characteristics

The incorporation of renewable energy microgrids brings along several new protection coordination challenges due to the new and stochastic behaviour of power flow and fault currents distribution. An optimal coordination scheme is a potential solution to develop an efficient protection system to handle the microgrid protection challenges. In this paper, new optimal Over Current (OC) relays coordination schemes have been developed using nonstandard tripping characteristics for a power network connected to renewable energy resources. The International Electrotechnical Commission (IEC) microgrid and IEEE-9 bus systems have been used as benchmark networks to test and evaluate the coordination schemes. The proposed OC relays coordination approach delivers a fast and more reliable performance under different OC faults scenarios compared to traditional approaches. In addition, to improve and evaluate the performance of the proposed coordination approach, four modern and novel metaheuristic optimization algorithms are developed and employed to solve the OC relay coordination problem, namely: Modified Particle Swarm Optimization (MPSO), Teaching Learning (TL), Grey Wolf Optimizer (GWO) and Moth-Flame Optimization Algorithm (MFO). In this paper, the modern metaheuristic algorithms have been employed to handle the impact of renewable energy on the grid, and enhance the sensitivity and selectivity of the protection system. The test cases, consider the impact of integrating the different levels of renewable energy resources (with a capacity increment of 25% and 50%) in the microgrid on the OC relays protection performance by using nonstandard and standard tripping characteristics. In addition, a comparison analysis for the modern metaheuristic algorithms with Particle Swarm Optimization (PSO) algorithm as a common and standard technique in solving coordination problems under different fault scenarios considering also the higher impedance faults are introduced. The results in all cases showed that the proposed optimal nonstandard approach successfully reduced the overall tripping time and improve the performance of the protection system in terms of sensitivity and selectivity.

A complementarity model for electric power transmission-distribution coordination under uncertainty

The growing penetration of stochastic renewable energy sources increases the need for operational flexibility to cope with imbalances. Existing proposals for flexibility procurement are envisioning markets where the transmission system operator (TSO) can access flexible resources located at the distribution system operator (DSO)-level and vice versa, but the coordination between these two entities is a matter of active research. We consider two trading floors, i.e., day-ahead and real-time markets, and propose a method for day-ahead coordination on how to share flexible resources, described as a complementarity model. The proposed coordination approach is to optimize prices and capacity limits at the physical interface of TSO and DSO, the so-called “coordination variables”. For given values of these variables, the DSO pre-qualifies the participation of DSO-level resources in the day-ahead market by capping their quantity bids. This way, the DSO ensures that the constraints of its system, modeled by a conic program, will be respected. Pursuing computational tractability, we decompose the model using a multi-cut Benders’ decomposition approach. It separates the conic modeling of real-time power flows under each scenario from the mixed-integer linear formulation of the day-ahead market-clearing problem. We quantify the potential benefit of the proposed coordination method in terms of improved social welfare. Using an ex-post out-of-sample simulation, the performance of the proposed coordination method is assessed against two benchmarks: (i) a fully uncoordinated scheme which obtains a lower bound for the expected social welfare, and (ii) an ideal benchmark which co-optimizes the TSO and DSO problems, providing an upper bound for the expected social welfare.

Evaluation of benefits through coordinated control of numerous thermal energy storage in highly electrified heat systems

This paper proposes a novel decentralised control approach dedicated to coordinating the operation of a large population of residential thermal energy storage characterised by diversified specifications, while innovatively considering the operational constraints on both the national and the local level. The presented iterative algorithm sequentially updates the storage operational schedule under the real-time electricity price scheme to achieve cost savings for each individual participant and the total system, while effectively avoiding the violation of local distribution network restrictions. The transmission topology is explicitly considered to investigate the impacts of transmission congestion on the electricity marginal prices. The results of a series of case studies demonstrate that the proposed coordination approach can effectively enable individual energy arbitrage and achieve 22.53 % system cost savings compared to the 10.34 % savings when coordination is absent. Moreover, the simulation results manifest that the coordinated control approach can cost-effectively perform distribution congestion management to ensure no local network is overloaded, which will cause 12.3 % increase in system operational costs. Overall, through coordinating the operation of numerous residential thermal energy storage to perform both energy arbitrage and distribution network congestion management, the proposed control approach can benefit the system operation at both the national and local levels.

Adaptive optimum coordination of overcurrent relays for deregulated distribution system considering parallel feeders

This paper proposes an adaptive optimum overcurrent protection for deregulated distribution networks containing parallel feeders. The proposed adaptive coordination eliminates the maloperation of conventional overcurrent protection under different fault scenarios. These scenarios take place when faults occur close to the end of the parallel feeders specially when faults are associated with significant fault resistances. Under these faults, the current at the backup relay is almost double that at the corresponding primary. Thus, adaptive pickup setting is recommended. However, this problem is complicated remarkably when distributed generation units feed the upstream source side faults or under the removal of the power source due to the interruption of a source side breaker. Simultaneously, the proposed coordination approach enhances the sensitivity and keeps on the optimum speed by automatically identifying the faulted zone. The faulted zone is identified by monitoring both the status concerning a single feeder or two parallel feeders in service and the faulted phase current direction of each pair of relays. Thus, a new fault direction identification method is presented. This method is based on comparing the angle of the post-fault current and that of the pre-fault current. Three optimization algorithms (genetic, harmony search, and water cycle algorithms) have competed to find the optimal settings of the installed overcurrent relays for each faulted zone. The reliability of the proposed method is examined as compared to conventional coordination concepts based on a detailed simulation of an actual 11-kV cascaded parallel series distribution feeder in the Egyptian distribution network. Sample results are examined.

A nonlinear coordinated approach to enhance the transient stability of wind energy-based power systems

This paper proposes a novel framework that enables the simultaneous coordination of the controllers of doubly fed induction generators &#x0028 DFIGs &#x0029 and synchronous generators &#x0028 SGs &#x0029 . The proposed coordination approach is based on the zero dynamics method aims at enhancing the transient stability of multi-machine power systems under a wide range of operating conditions. The proposed approach was implemented to the IEEE 39-bus power systems. Transient stability margin measured in terms of critical clearing time along with eigenvalue analysis and time domain simulations were considered in the performance assessment. The obtained results were also compared to those achieved using a conventional power system stabilizer &#x002F power oscillation &#x0028 PSS &#x002F POD &#x0029 technique and the interconnection and damping assignment passivity-based controller &#x0028 IDA-PBC &#x0029 . The performance analysis confirmed the ability of the proposed approach to enhance damping and improve system &#x02BC s transient stability margin under a wide range of operating conditions.

Interval Optimization Based Coordination of Demand Response and Battery Energy Storage System Considering SOC Management in a Microgrid

Microgrids can effectively integrate distributed generation (DG) to supply power to local loads. However, uncertainties from renewable DG and loads may lead to increased operating costs or operating constraint violations. To solve these issues, this paper proposes a two-stage coordination approach of price-based demand response (PBDR) and battery energy storage systems (BESSs) to minimize the total operating cost and enhance operational reliability. In the first stage, day-ahead PBDR is scheduled, aiming to shift loads to improve renewable energy utilization efficiency. Considering limited prediction horizon of uncertainties when dispatching BESSs, hourly state of charge (SoC) limits are also optimized over the whole-day horizon with consideration of BESS degradation cost in the day-ahead stage. Then in the second stage, the BESSs are dispatched hourly within the optimized SoC limits to track uncertainty realization and compensate the first-stage PBDR decisions. Furthermore, a two-stage interval optimization (TSIO) method is proposed to formulate the problem. Accordingly, a solution algorithm is developed to coordinately solve the two operation stages under the uncertainties. The proposed coordination approach is verified with uncertainty realization scenarios. The results indicate the high energy utilization efficiency and strong operational reliability of the proposed coordination approach.

Coordinated Voltage Control Strategy for Voltage Regulators and Voltage Source Converters Integrated Distribution System

This paper presents a situational-aware, data-driven, and agnostic-coordinated control methodology for voltage regulation in the active distribution systems (DS) considering voltage source converters (VSCs) as reactive power sources that work in conjunction with the existing legacy controllers. The approach uses time-scale coordination based on regulator warnings such that the voltage support from regulators is time separated from the reactive power support using VSCs. Two type of voltage changes are considered; a slow changing one based on the feeder load and a fast-changing one based on sudden changes in load or PV output. The reactive support for both these changes is then designed based on the voltage to reactive power sensitivities. The combined reactive support is then used as a set-point to dispatch reactive power from the VSCs. The proposed control technique has been tested in the field verified model of a real feeder and the scalability is verified on an 8500-node real feeder. Results show that the proposed coordination approach has major economic as well and power quality benefits in the operation of DS. It has also been shown that this can be achieved without major changes in the communication framework currently utilized by the utility.

Adaptive Protection Coordination Scheme Using Numerical Directional Overcurrent Relays

Dynamically changing distribution system operating conditions compromises the coordination of the existing protection schemes. This paper proposes an online adaptive protection coordination scheme by utilizing numerical directional overcurrent relays (DOCRs) and commercial A Mathematical Programming Language (AMPL) based Interior Point OPTimization (IPOPT) solver. The proposed scheme also utilizes intelligent electronic devices and a communication channel to obtain real-time system information and to update relays settings. The presented approach is able to handle different operating conditions of the system, including loss of loads, generations, and lines. Further, the miscoordination arising due to injections of distributed generations (DGs) is also handled. The proposed approach has been tested on the IEEE 14-bus system (with and without DG), under various operating conditions. Overall system reliability enhancement using the proposed approach has been analyzed in terms of the amount of energy not supplied. Further, the optimum settings of DOCRs obtained using AMPL based IPOPT solver has been compared with those obtained by General Algebraic Modeling System based Sparse Nonlinear OPTimizer solver, OPTI Toolbox based IPOPT solver, MATLAB based interior point method, and metaheuristic genetic algorithm and differential evolution. It has been found that the proposed coordination approach gives good results in reasonably small time and thus, is suitable for the adaptive protection scheme.

Coordinated Ramp Metering Based on On-Ramp Saturation Time Synchronization

In this paper, a coordinated ramp-metering approach is proposed; the approach is based on the synchronization of the time it takes for an on-ramp to run out of space. The time that congestion and the associated capacity drop can be prevented at a freeway bottleneck by means of ramp metering depends on the available ramp space for temporarily storing the vehicles. For a single on-ramp, the available space and thus the metering time at the bottleneck are often limited. By means of coordination, upstream storage space can be used to prevent a breakdown for a longer period of time. To accomplish that aim, upstream ramps need to reduce their inflow into the mainstream with respect to their own metering task. The extent to which upstream inflow reductions are effectively used to extend the metering time at the bottleneck is determined by the order and timing at which the coordinated ramps run out of space. The proposed approach aims at always saturating the more upstream-located ramps before more downstream-located ones; that is, the ramps run out of space in the downstream direction to make sure that all realized assistance is used by the ramp that is metering at the bottleneck. By means of a simulation test case, the functioning of the algorithm is demonstrated and compared with a no-control scenario, local ramp metering, and an alternative coordination algorithm that aims at filling the ramps equally. Both coordination approaches strongly improve the network performance with respect to local ramp metering, but the proposed coordination approach is able to postpone the breakdown for a longer period of time.

A Constraint Satisfaction Coordination Approach for Distributed Supply Chain Production Planning

Currently, distributed supply chain production planning (SCPP) is a practical problem affecting global supply chain production. Distributed SCPP is a complex constraint satisfaction problem (CSP) comprising a series of constraints intra- and inter-production members on orders, capacity, and materials. Previous studies have proposed various advanced planning and scheduling (APS) algorithms for companies to solve internal CSPs related to production planning. Distributed SCPP problems additionally require a coordination approach to resolve conflicts among the production plans of individual production members. Several distributed CSP (DCSP) algorithms have been proposed to guide the coordination for various DCSP conditions and objectives. Based on these techniques, we propose a coordination approach for achieving consistency among individual production plans to develop an integral supply chain production plan. First, we employed an APS system to resolve the internal production planning constraints and to develop a feasible production plan for each production member. Next, we developed a hybrid DCSP coordination algorithm based on agent-ordering asynchronous weak-commitment search (AWS) algorithm and asynchronous incremental relaxation (IR) algorithm concepts to facilitate production planning coordination and resolve constraint conflicts among individual production plans. Finally, a thin-film transistor liquid crystal display (TFT-LCD) supply chain was used to illustrate and verify the proposed coordination approach.

A Heuristic Approach for Coordination of Plug-In Electric Vehicles Charging in Smart Grid

In this paper, a heuristic load management algorithm (H-LMA) is proposed for Plug-in Electric Vehicles (PEVs) charging coordination. The proposed approach is aimed to minimize system losses over a period T (e.g., 24 hours) through re-optimizing the system at time intervals (e.g., 15 minutes) while regulating bus voltages through future smart grid communication system by exchanging signals with individual PEV chargers. Scheduling is performed based on the allowable substation transformer loading level and taking into account PEV owner preference/priority within three designated charging time zones. Starting with the highest priority consumers, H-LMA will distribute charging of PEVs within the selected priority time zones to minimize total system losses over a period T while maintaining network operation criteria such as power generation and bus voltages within their permissible limits. Simulation results are presented for different charging scenarios and are compared to demonstrate the performance of H-LMA for the modified IEEE 23 kV distribution system connected to several low voltage residential networks populated with PEVs. The main contribution of this paper lies in the detailed simulations / analyses of the smart grid under study and highlighting the impacts of and T values on the performance of the proposed coordination approach in terms of accuracy and coordination execution time.

Coordination for replicated collaborative feature modeling

Collaborative feature modeling has been proposed and applied in product design for improving design quality and shortening lead-time. The coordination mechanism for scheduling the collaborative design activities has been a topic of significant research effort. Total-locking mechanism and granular locking mechanism have been reported. However, these granular locking mechanisms have some limitations. Although the designers can edit different parts of a feature model at the same time, there are some conflicts due to feature interactions. Besides, in order to maintain consistency of the replicated design models, the order of execution of the ‘feature create operations’ must be kept consistent at the client sites. In this research, a fine granular locking mechanism is proposed for a replicated collaboration system. The locking granularity is defined according to feature relationships, and the potential operation conflicts are resolved using a naming and matching mechanism. In the proposed approach, a design model can be divided into several feature portions, thus a parallel working paradigm can be achieved. The ‘feature create operation’ is processed differently from the ‘feature modify operation’ so as to maintain consistency of the order of the features created. The limitation of this approach is that the effectiveness depends on the parent–child relations of the features. The proposed coordination approach has been validated in a proof-of-concept prototype system developed based on Java and Open CASCADE.

The Intelligent Vehicle Coordination of the Cybernetic Transportation System

Cybernetic Transportation System (CTS) is a new branch of Intelligent Transportation Systems (ITS), which is a solution to the urban transportation problem. The coordination of intelligent vehicles is critical for the operation of the Cybernetic Transportation System. We present a distributed coordination approach for the intelligent vehicles of the Cybernetic Transportation System, which is based on an agent-based framework. Each vehicle agent generates intention independently by considering its and other agents' shared status and intentions in the coordination. Typical coordination scenes, including platoon and overtaking, have been demonstrated in the two-lane, two-way traffic situation and the effectiveness of the proposed coordination approach has been validated.