Osman Bulent Tor

Congestion-Driven Transmission Planning Considering the Impact of Generator Expansion

This paper presents a multi-year transmission expansion planning (TEP) model which considers the transmission congestion and the impact of generation investment cost in the planning horizon. The Benders decomposition approach is utilized which decomposes TEP into a master problem and two subproblems representing security and optimal operation. The operation cost due to congestion (OCC) is considered in the proposed model given that the congestion level is a proper criterion for measuring the degree of competitiveness in an electricity market. The model evaluates sensitivity of the optimal TEP to congestion level, planning horizon, and financial constraints. Regulators can utilize the proposed results to provide long-term TEP to market players and to develop incentive mechanisms to trigger generation investments. The proposed approach is applied to a hypothetical system and Turkish power system.

Power distribution asset management

The principal objective of the asset management in a power distribution utility enterprise (DUE) is to guide the acquisition, use and disposal of distribution system assets to provide the level of service required by customers in the cost-effective manner, encompassing the strategic planning, maintenance and utilization and operation of a physical resource throughout its life. This study categorizes the asset management strategies of a (DUE) based on short-term, mid-term and long-term timescales and shows that their coordination plays a critical role in making strategic decisions. Short-term asset management is related with operational issues. Secure and reliable operation of the network, system monitoring and control, fault restoration are among the issues discussed in the paper. The issues regarding the maintenance of assets including the optimal maintenance strategy and optimal outage plan are presented under the title of mid-term asset management. Finally, strategic planning is discussed, where distributed generation (DG) is evaluated in the context of long-term system planning strategy. The utilization of information technologies (IT) plays a central role in the asset management of a DUE in all timescales

Damping measures against prospective oscillations between Turkish grid and ENTSO-E System

After the synchronous interconnection of Turkish Power System to ENTSO-E CESA (former UCTE) System, inter-area oscillations in the range of 0.15 Hz are prone to occur, according to simulation studies. Therefore, some preventive measures should be considered in order to ensure stable operation of the network after the interconnection. This study summarizes the effects of following measures based on computer simulations: 1) Retuning of power system stabilizers (PSS) of the important power plants in Turkey, 2) Controller modification of static VAR compensators (SVC) existing in steel melting arc furnaces that are supplied directly from the transmission system, 3) Controller modification of ±50 MVAR STATCOM which is designed for voltage regulation, 4) Application of breaking resistors as a backup measure in case of malfunctioning of the other solutions. In addition to individual analysis of each measure, their combined contribution is also analyzed. A load flow scenario, in which Turkey exports 900 MW to ENTO-E CESA System, is utilized as a reference scenario. In simulations, Turkish grid is represented in detail and a reduced representation of ENTSO-E CESA network, which consists of 75 nodes and 133 lines, is utilized. The results show positive contribution of each measure to system damping performance. The study includes comparison of each preventive measures contribution level and conclusive recommendations.

Promoting the Investment on IPPs for Optimal Grid Planning

This paper presents a transmission expansion planning (TEP) model which coordinates investment decisions in monopolistic transmission and decentralized generator sectors. The proposed planning approach gauges transmission congestion and security constraints with respect to transmission investments while promoting investments on independent power produces (IPPs) through incentive payments. The paper includes discussions on incentive mechanisms and prioritization among qualified IPPs for several planning scenarios. Such incentives might be necessary to trigger investments on IPPs earlier than those projected by the decentralized generation system, when the power system security is threatened. The proposed planning approach would optimize the sum of transmission investments, incentive payments to IPPs, and congestion costs along the planning horizon. The case studies illustrate how the proposed planning algorithm could be utilized in order to determine incentive payments to candidate generators when necessary, and prioritize such incentives among multiple IPP candidates.

Transmission and substation expansion planning using Mixed Integer Programming

This paper presents a novel planning approach which optimizes size and location of new transmission substation (TS) investments considering capacity expansion of the existing TSs based on primary distribution network investment requirements. Mixed Integer Programming (MIP) is utilized and the problem is decomposed into investment and feasibility check subproblems. The algorithm is formulated to minimize total investment cost while supplying the spatial forecasted load considering a set of system constraints. The results of two numerical examples indicate that presented algorithm is adequate for determining requirements of new transmission substations and/or capacity expansions together with new HV/MV lines, via appropriate selection of candidates. Visualization of the planning algorithm results, in an iterative manner, gives very important verification signals regarding the necessity of the proposed investments.

Assessment of the effect of hydroelectric power plants' governor settings on low frequency inter area oscillations

This paper deals with the specific problems of the electromechanical systems of large size hydroelectric power plants regarding low frequency inter area oscillations, which are prone to occur once the interconnected operation of Turkish Power System with the ENTSO-E CESA (former UCTE) System is established. The expected frequency of inter area oscillations is close to 0.15Hz, which is in the frequency range of interest of speed governing structures of turbines, as shown in the first and second parts of the paper. In the proceeding part, the governor parameter tuning study with regard to the defined objectives considering the contingency handling and system stability is explained and the effect of retuned governor settings of the sample hydroelectric power plant on the multi machine system is shown. In the final part, conclusions are made regarding the operation and dispatch of hydroelectric power plants in synchronous interconnected operation of the Turkish Power System and the ENTSO-E CESA System.

Crossroads of Power: Coordinating Electricity and Natural Gas Infrastructures in Turkey

Electricity continues to be the cornerstone of every developing economy, with many untapped opportunities for growth and enhanced efficiency (see Figure 1). Over the last few decades, the global consumption of energy has continued to grow (see Figure 2) while the inherently slow-changing electric power industry was subject to market fluctuations, government support of renewable generation, and tightening environmental regulations, all of which have led to the shrinking of the traditional coal-fired generation base. Many questions have also been raised about the future of nuclear-powered units. A large increase in global natural gas usage (see Figure 3) has compounded these strains; the installation of a large number of gas-fired generators is leading the power industry toward a new and revolutionary paradigm: the coordination and possible integration of interdependent natural gas and electricity systems.

A geographical zoning methodology for nodal transmission use-of-system tariffs

Power systems are generally separated into transmission use-of-tariff (TUoT) zones to simplify the tariff mechanism, particularly for large grids. Each zone is an aggregation of neighboring nodes with similar tariffs that are determined based on long-run marginal cost (LRMC) calculations. This paper proposes a zoning methodology which ensures diversification of zonal tariffs while geographically aggregating the nodal TUoTs by weighted average approach. Investment cost-related pricing (ICRP) and DC-load-flow pricing (DCLFP) methods are utilized in computing the LRMC based nodal tariffs. Performance of the LMRC based pricing methods, sensitivity of the economical parameters on the results, and the proposed zoning approach are investigated for a simple 12-bus generic power system. Given the satisfactory results, TUoT zones of Turkish power network are determined with the proposed zoning algorithm for the tariff period of 2012-2014.

Distribution substation optimization at primary distribution network planning and visualization of the results

In a primary distribution network planning problem, determination of total number and size (i.e., additional total capacity) and siting of new distribution substations (DS) are among the first important tasks of planners who are responsible from supplying the loads securely, keeping the medium voltage level in defined limits and thereby minimizing losses. This paper presents a methodology to optimize total capacity and siting of new DSs based on spatial load forecast (SLF) results. Objective function minimizes total loss of the primary network while considering security constraints of the network. Given the proportionality between voltage drop and losses, the minimization of losses inherently takes into account minimization of voltage drops as well. First, a grid (250×250 m2) based distribution system is constructed on Microsoft Office (MS) Excel TM and based on a 10 year SLF assumption which takes into account different growth characteristics of the grids, all the loads are assumed to be supplied by the existing DSs along the planning horizon. Then, the proposed algorithm relaxes the overloaded DSs by placing pre-defined alternative DSs in an optimum manner while satisfying the network security constraints.

Lessons learnt from interfacing ArcGIS and DIgSILENT powerfactory at Başkent DISCO

Smart grids require not only smart tools to automatize grid operation and planning processes but also require smart approaches to maximize utilization of the capabilities of those tools as well. Geographic information systems (GIS) provide an integrated suite of software for visualizing the system data, tools for network optimisation, and a range of automation and information processing systems which assist in the operation, maintenance and planning of distribution networks. Interfacing of GIS data with sophisticated power system simulation tools facilitates model updating process for the network planner who needs updated network data for operational and planning analysis. Quality and quantity of data in GIS database generally limit the planners. This paper presents a smart process for interfacing GIS based database with power system simulation tools, based on the lessons learnt from interfacing ArcGIS with DIgSILENT PowerFactory at Başkent DISCO.