Transmission Network Planning Research Articles

Research on load transfer planning model for equipment maintenance in the substation

The maintenance, inspection, and refurbishment of substation equipment are crucial for ensuring the stability of the power grid’s operation and the reliability of power supply to users. However, currently, there is a lack of methods for rapidly and effectively planning load transfer solutions during substation equipment maintenance periods. To address this, this study is founded on the principles of transmission network planning theory, and an analysis of the similarities and disparities between the planning methods for load transfer solutions during substation equipment maintenance and traditional approaches to transmission network planning is conducted. Furthermore, this paper integrates practical constraints related to maintenance engineering and power grid load flow balance constraints. With the primary optimization objectives of minimizing investment and operational costs during system maintenance while maximizing power grid reliability, a load transfer planning model for equipment maintenance in the substation has been developed. Simultaneously, in conjunction with linear programming theory, the nonlinear constraint terms of the model have been equivalently simplified to enhance the computational performance of the model. Simulation analysis is conducted on case studies constructed based on the IEE-RBTS6 and IEEE-RTS79 systems to validate the effectiveness of the proposed model in solving the optimal maintenance planning problem.

A method for economic expansion planning of transmission networks using heuristic rules and non-linear optimization model

A method for economic expansion planning of transmission networks using heuristic rules and non-linear optimization model

Integrated Transmission Network Planning by Considering Wind Power’s Uncertainty and Disasters

The penetration of wind turbines and other power sources with strong uncertainty into the grid has increased in recent years. It has brought significant technical challenges to power systems’ operation. The volatility and intermittency of wind power increase the risk of insufficient transmission capacity of the lines. Therefore, the traditional deterministic planning methods for transmission grids are no longer fully applicable. On the other hand, the frequent disasters in recent years have posed a great threat to the power system, especially for the transmission grid. This requires the design of transmission lines with high design standards, such as skeleton networks, to withstand disasters. With the aim to address these problems, a bi-level integrated network planning model for the transmission grid is developed by considering wind power’s uncertainty and load guarantee under disasters. Chance constraints are used in the model to characterize wind power’s uncertainty, and a skeleton network is adopted to cope with disasters. Moreover, based on a convex relaxation method, the chance constraints are converted into the probabilistic inequalities to be solved. The proposed method is simulated in the IEEE 118 bus system, and the obtained network planning scheme is further analyzed in the scenario tests. And the result of the tests proves the validity and reasonableness of the proposed method.

Hierarchical market-based optimal planning of transmission network and wind-storage hybrid power plant

Coupling renewable energy sources (RES) such as wind farms with energy storage systems (ESSs) to form a hybrid power plant (HPP) has gained increasing attention. However, its investment profitability is closely associated with its capacity configuration, site location, grid network, and market-clearing outcomes. To study the HPP’s planning strategy and its interaction with the transmission system operator (TSO), this paper proposes a tri-level coordinated planning scheme for transmission networks and a profit-driven wind-storage hybrid power plant (WSHPP) in the electricity market. The upper level is the transmission network expansion problem managed by the TSO, which responds to the investment decision of the WSHPP. The middle level determines the optimal capacity and site location of the WSHPP to maximize net benefits given transmission expansion schemes and prices from the third level. In the third level, the independent system operator (ISO) solves a scenario-based economic dispatch problem to provide locational marginal prices with fixed upper-level and middle-level decisions. The proposed tri-level hierarchical optimization model is computationally intractable because of its multi-level structure and binary/integer variables at the upper/middle level. A value-function reformulation and sample-based algorithm is implemented to solve the tri-level planning model and the convergence is proved. Numerical experiments on two typical test systems show the effectiveness of the proposed planning scheme and the tractability of the solution algorithm.

Coordinated expansion planning of transmission and distribution systems integrated with smart grid technologies

Integration of smart grid technologies in distribution systems, particularly behind-the-meter initiatives, has a direct impact on transmission network planning. This paper develops a coordinated expansion planning of transmission and active distribution systems via a stochastic multistage mathematical programming model. In the transmission level, in addition to lines, sitting and sizing of utility-scale battery energy storage systems and wind power plants under renewable portfolio standard policy are planned. Switchable feeders and distributed generations are decision variables in the distribution level while the impact of demand response programs as a sort of behind-the-meter technologies is accommodated as well. Expansion of electric vehicle taxi charging stations is included as a feasible option in both transmission and distribution levels. In order to deal with short-term uncertainty of load demand, renewable energy sources output power, and the charging pattern of electric vehicle taxis in each station, a chronological time-period clustering algorithm along with Monte Carlo simulation is utilized. The proposed model is tackled by means of Benders Dual Decomposition (BDD) method. The IEEE RTS test system (as the transmission system) along with four IEEE 33-node test feeders (as distribution test systems) are examined to validate effectiveness of the proposed model.

Power and Electricity Balance Analysis Method Based on the Full Sequence Production Simulation Method

The goal of “carbon peaking and carbon neutralization” has accelerated the pace of China’s energy transformation and power grid upgrading. During the 14th Five Year Plan period, the characteristics of the high proportion of new energy and multi-DC transmission in the power system have become increasingly prominent, and the ‘double peak’ load characteristics have gradually emerged. The power grid is facing the challenges of power shortage and new energy obstruction in some periods. Therefore, considering the growth of power installed capacity and load level, according to the power balance and the new energy consumption of the provincial power transmission network, the full sequence production simulation method is used to analyze the power and electricity balance of the whole network considering the energy storage device and demand side response to provide support for the provincial power transmission network planning during the 14th Five Year Plan period.

Constrained Fuzzy Power Flow Applied to Transmission Congestion

The deregulation of the electricity industry, the increasing penetration of renewable energy resources, and the presence of new stakeholders, such as Electric Vehicles (EV), make managing transmission system congestion critical. In this context, load flow methodologies that consider non-probabilistic uncertainty due to a lack of data (particularly concerning EV) seem to be a handy tool to analyze network congestion situations and to support electrical network planning. The congestion of the branches is related to the load and generation of the network buses. Still, the congestion of a specific branch may not be related to the load and generation on the neighbouring buses. In this line, Fuzzy Power Flow (FPF) is suitable for identifying congestion situations in the transmission system and the branches responsible for such cases when probabilistic models may not describe uncertainty. This paper uses an FPF model, a non-linearized Constrained Fuzzy Power Flow (CFPF), to characterize congestion situations in transmission network planning. The application of the CFPF to analyze congestion situations is a novelty. The results of that application may be used to define the reinforcement of the most appropriate branches to achieve specific suitability of the network in the face of a diverse set of uncertainties. Furthermore, the dual values provided by Lagrange multipliers resulting from the CFPF optimization problem are used to identify the most promising options to mitigate congestion situations.

Joint Planning of Electricity Transmission and Hydrogen Transportation Networks

The abundance and uneven distribution of renewable energy might cause congestion and curtailment in electric power systems. Transmission expansions can potentially alleviate transmission congestion and reduce renewable energy curtailment. On the other hand, with the substantial cost reduction of electrolyzer technology and the continuing rise of hydrogen demand, converting surplus renewable energy to hydrogen provides synergistic benefits to power and hydrogen systems, but consequently requires joint planning of the two systems. To this end, we propose a joint planning approach for power transmission and hydrogen transportation networks to coordinately optimize the investment and operation of power and hydrogen infrastructure. In our proposed model, detailed truck routing, pipeline, and hydrogen storage are formulated to quantify the flexibility of hydrogen transportation system. A robust joint planning approach is also proposed to address various uncertainties from renewable energy, electric load, and hydrogen demand. Our numerical simulations show that the proposed joint planning model can save the total system cost, reduce renewable energy curtailment, and increase the utilization level of transmission lines.

Research on evaluation of minimum backbone grid of transmission network based on differentiation planning

The essence of the differential planning of transmission network is to evaluate the minimum backbone grid of transmission network, and the evaluation of the backbone grid of transmitting minimum network includes the evaluation of important nodes and the evaluation of important lines. In this paper, the important node evaluation of the transmission network takes into account the structural fragile nodes and the important load nodes, and the important line evaluation is based on the line number, which is considered synthetically from the point of view of the structural fragile line and the important load line. The minimum backbone grid of transmission network is constructed by the structure backbone grid and the important load backbone grid.

Co-optimization of distribution system operation and transmission system planning: A decentralized stochastic solution

The distribution system is normally equivalent as a dynamic power injected at the interconnected transmission bus. This cannot unlock the potential benefits of transmission–distribution interaction. To tackle this problem, this paper proposes a distributed stochastic optimization approach to simultaneously determine distribution system operation and transmission system planning. Uncertainties in the distribution and transmission systems are modelled using numbers of typical scenarios. The original problem is decomposed into the upper transmission network planning level and the lower distribution network operation one. Both two levels are linearized using a piecewise linearization approach to guarantee the convergence properties of the algorithm. Simulation results investigated on the integrated T24D9 system testify the high performance of the presented distributed framework. With the coordination of distribution systems, the transmission network planning solution decreases the investment and improves the renewable energy recommendation.

Applying a Model of Technology Diffusion to Quantify the Potential Benefit of Improved Energy Efficiency in Data Centres

Data centres are a key infrastructure for the global digital economy, helping enable the EU “Digital Decade” by 2030. In 2015, data centres were estimated to consume 2.5% of EU electricity demand. In Ireland, the concentrated presence of data centres could consume 37% of national electricity demand by 2028. The uncertainty of data centre facility-level energy efficiency paired with the need to achieve a low-carbon economy pose significant challenge for generation and transmission network planning. This is the first paper to apply a model of technology diffusion with a national forecast of changes in Irish data centre electricity demand through more efficient liquid cooling. The methodology serves as a technology-agnostic resource for practitioners performing forecasts under uncertainty with limited information. Results suggest that technology adoption could lower national electricity demand by 0.81% if adopted by new plant from 2019 to 2028. Savings rise to 3.16% over the same period if adopted by new and existing data centres. Adoption would also lower related emissions by 4.70% and 23.04% over the same period across both scenarios, respectively. Results highlight substantial potential electricity and associated emissions savings available in the sector and suggest policy options to support a transition towards a low-carbon economy.

Coordinated expansion planning problem considering wind farms, energy storage systems and demand response

During the recent years, the power system has entered a new technological era. The trends associated with increased commitment to wind farms (WFs) and energy storage systems (ESSs) as well demand side flexibility require disruptive changes in the existing power system structures and procedures. Being at the heart of a paradigm shift from passive users of the grid to active prosumers, storage owners and demand responsive actors, this paper expresses a flexible coordinated power system expansion planning (CPSEP) while considering local WFs, ESSs and incentive-based demand response programs (DRPs). This model minimizes the summation of the expansion planning, operation and reliability costs while taking the network model based on AC optimal power flow constraints, and the reliability and flexibility considerations into account. The proposed framework is firstly formulated by mixed integer non-linear programming (MINLP), then to have a well-handed optimization model it is converted to mixed-integer linear programming (MILP). Additionally, the uncertainties of load, energy price, maximum WF generation and availability/unavailability of the network equipment are included in the proposed model where the first three parameters are modeled based on the bounded uncertainty-based robust optimization (BURO), and the scenario-based stochastic programming (SBSP) is used to model the last uncertain parameter. Finally, the proposed method is examined on several test networks to assess the performance of the proposed framework for flexi-reliable transmission network operation and planning.

Tri-level coordinated transmission and electrical energy storage systems expansion planning under physical intentional attacks

In this paper, a model for tri-level coordinated expansion planning of transmission and electrical energy storage systems (ESSs) is proposed to decrease the destructive effects of physical intentional attacks. In order to implement the actions of the system planner (SP), attacker, and system operator (SO), the optimization problem is modeled as a planner-attacker-defender problem. In the first level, the SP determines the optimal coordinated expansion planning of transmission networks and ESSs. In the second level, having enough knowledge about the network, the attacker wants to inflict the maximum damage. In the third level, the SO endeavors to minimize the damage to the network by exploiting correcting actions, such as load shedding and generators and ESSs re-dispatch. To confront the mathematical complexity of the presented model, we propose a mathematical model to convert the tri-level problem to a single-level mixed integer linear programming problem. The model is implemented on Garver and modified IEEE 30-bus test systems, and numerical results are provided for various case studies. The obtained numerical results are compared by literature. The numerical results show the effectiveness of the model to reduce power systems vulnerability.

Research on Transmission Resource Allocation in Communication Management System

This paper studies the completion of power communication technology and transmission network planning. It summarizes the basic research and current situation analysis of transmission technology and business network planning. First, it focuses on the functions of power communication business, information flow, transmission channels and bearing requirements. The characteristics of various power grid technologies and grid communication business models in China are analyzed. Secondly, it carried out analysis and research on the basic design principles of power communication technology and transmission network business planning, evaluation of main indicators, and focused on elaborating the digital communication network management system of synchronous transmission of power communication, the characteristics of ason power communication technology, network protection and management and basic principles of power communication technology and transmission network such as restoration.

Joint Planning of Transmission and Distribution Network Considering Wind-solar Complementarity

The temporal and spatial distribution characteristics of wind power and photovoltaic output are complementary to a certain extent, which can stabilize the volatility of single new energy power generation to a certain extent and improve the ability of the grid to absorb new energy. This paper aims to study the joint planning method of power transmission and distribution network considering the complementary characteristics of wind-solar time and space. First, a wind-solar joint distribution model based on the time-varying Copula theory is established, and a wind-solar output simulation method considering the complementary characteristics of time and space is proposed. Then, taking the system investment and new energy consumption capacity as the optimization goals, and taking the system power balance, line transmission capacity, conventional generator set output and climbing capacity as constraints, the joint planning model of transmission and distribution network is established. At last, the analysis of calculation examples proves that the joint planning model of transmission and distribution network considering the complementary characteristics of wind-solar time and space can significantly improve the capacity of the grid to absorb new energy.

Market-Based Coordination of Transmission and Distribution Network Planning with Distributed Energy Resources Planning

Distributed energy resources (DERs) have the potential for the non-lines alternative in both transmission and distribution (T&D) systems. However, the value of DERs in substituting power lines in T&D systems is not revealed and coordinated planning of T&D networks and DERs under market environment is not studied in existing researches. This may damage the interests of DER investors, hinder the wide integration of DERs in power system and increase total cost under market environment. This paper proposes market-based coordination of transmission and distribution network planning (TDNP) with DER planning (DERP). The model is formulated as multi-stage programming. In first stage, transmission companies (TRANSCOs), distribution companies (DISCOs), and DER aggregators (DERAs) send their bidding plans to independent system operator (ISO) and distribution system operators (DSOs), respectively. In second stage, ISO and DSOs check the transmission and distribution network securities, respectively. In third stage, ISO and DSOs solve their optimal operation problems, respectively. An iterative solution algorithm is proposed to solve the multistage model. The solution embodies the interaction process among TRANSCOs, DISCOs, DERAs, ISO, and DSOs in electricity market. Numerical results demonstrate that the proposed model coordinates TDNP with DERP, promotes DER installations and reduces the total cost.

Multi-Stage Transmission Network Planning Considering Transmission Congestion in the Power Market

The uncertainty of generation and load increases in the transmission network in the power market. Considering the transmission congestion risk caused by various uncertainties of the transmission network, the optimal operation strategies of the transmission network under various operational scenarios are decided, aiming for the maximum of social benefit for the evaluation of the degree of scenario congestion. Then, a screening method for major congestion scenario is proposed based on the shadow price theory. With the goal of maximizing the difference between the social benefits and the investment and maintenance costs of transmission lines under major congestion scenarios, a multi-stage transmission network planning model based on major congestion scenarios is proposed to determine the configuration of transmission lines in each planning stage. In this paper, the multi-stage transmission network planning is a mixed integer linear programming problem. The DC power flow model and the commercial optimization software CPLEX are applied to solve the problem to obtain the planning scheme. The improved six-node Garver power system and the simplified 25-node power system of Zhejiang Province, China are used to verify the effectiveness of the proposed multi-stage planning model.

Hierarchical duality-based planning of transmission networks coordinating active distribution network operation

The active distribution network becomes more stochastic due to high penetration of renewable energy sources, and it can transfer surplus power for transmission needs. If the distribution optimization problem collaborates with the conventional transmission expansion formulation, the coordination can also postpone the investment decisions for the transmission network, not only optimize the operation of the entire power system. In view of these, this paper presents a bi-level hierarchy transmission expansion formulation coordinating distribution networks. The upper level of the hierarchical decision-making framework corresponds to the objective and constraints of the transmission network, whereas the lower level relates to the distribution perspective. An approximation technique is used to make the constraints of the distribution network linear, which guarantees that the proposed bi-level program can be solved using the duality-based approach. Numerical tests carried out on two transmission-distribution integration networks demonstrate the effectiveness and high performance of the proposed hierarchical duality-based model to accommodate renewable energy. In addition, sensitivities of the transmission investment decisions are analysed in terms of externalities in transmission and distribution networks. Compared with conventional isolated optimization, results show that the total costs of T24D9 and T38D3 by the proposed hierarchical coordinated optimization can respectively reduce by 34.38 M$ and 382.23 M$. So the economic benefits are remarkable, and the proposed optimization is reasonable and valuable.

An application of energy efficiency programs on multi-stage transmission network expansion and reactive power planning

Energy efficiency programs as an energy source with multiple advantages (low cost, more reliable and better clean) are considered as one of the most effective solutions to meet future energy needs. In this paper, energy efficiency programs are modelled as virtual sources of power generation to investigate their impacts on expanding transmission network and reactive power planning. A multi-stage model based on AC power flow has been used to indicate the possibility of postponing the investment actions as the investment deferral in transmission expansion problems. Two groups of regulatory support schemes are considered as investor income to promote participation in energy efficiency programs, namely purchasing certified emission reductions and shared saving model. In addition, two standard case studies (Garver & 46-bus Brazilian) are evaluated to demonstrate the promising potential of the proposed model in handling the planning problems of practical power systems. The simulation results show the effectiveness of the proposed model to solve such planning problems in the presence of energy efficiency programs.

Coordination planning of wind farm, energy storage and transmission network with high-penetration renewable energy

With larger scale renewable energy integrated, high-penetration renewable energy is deemed as one of the most important characteristics in the future power system. However, the inevitable uncertainty of both source and demand has brought significant challenges to planners. Since discoordination planning schemes restrict the optimal operation, a novel and efficient co-planning methodology is urgent to be investigated. Thus, we propose an innovative co-planning model of wind farm, energy storage and transmission network, which successfully takes imbalanced power, unit ramp capacity and incentive mechanism for renewable energy into consideration. To facilitate the renewable consumption, flexible implementations comprising optimal transmission switching (OTS) and unit commitment (UC) are integrated to further optimize the network topology and achieve flexible startup/shutdown of conventional unit. Furthermore, a linear tie-line model designed for multi-regional planning problems has been constructed to capture the presumed limitations. Afterwards, a decentralized decomposition algorithm based on analytical target cascading (ATC) is modified to deal with the proposed model through a completely parallel mode. The modified IEEE 48-bus test system demonstrates the priority of our proposed co-planning model and the corresponding solution algorithm.