Independent Power Producers Research Articles

Condition Assessment of Gas Insulated Switchgear Using Health Index and Conditional Factor Method

This paper proposes a comprehensive procedure to assess the condition of gas insulated switchgear (GIS) equipment by using the conventional weight and score method and introducing a conditional factor to improve the accuracy of the health index evaluation. Generally, the inspection and testing of GIS components are conducted according to manufacturer recommendations and guidelines in the international standards. However, this raw data has not been simplified and systematically processed for condition assessment. The score and weight technique are applied to transform the physical condition according to visible and measurable aging to numerical values in terms of component and bay health index values. The accuracy of the obtained health index has been improved by a conditional factor, which considers invisible aging factors, such as age, number of switching operations, degree of satisfactory operation, obsolescence, and adequacy of the interrupting rating. Here, a condition evaluation procedure has been developed and compared with the fuzzy logic method and the health index dominant score technique with satisfactory results. Subsequently, the proposed procedure has been developed as web application software to evaluate 175 bays of GIS in both 115 and 230 kV networks of an independent power producer supplying electricity of 3094 MW to a large industrial estate in Thailand. Eight GIS bays showed moderate or poor condition and the proper actions were assigned to prevent their failure. The software is in use in practice as a decision support tool to effectively manage the maintenance tasks and to improve supply reliability.

Multiobjective Salp Swarm Algorithm Approach for Transmission Congestion Management

In the newly emerged electric supply industry, the profit maximizing tendency of market participants has developed the problem of transmission congestion as the most crucial issue. This paper proposes a multiobjective salp swarm algorithm (MOSSA) approach for transmission congestion management (CM), implementing demand side management activities. For this, demand response (DR) and distributed generation (DG) have been employed. For willingly reducing the demand, demand response has been called by providing appropriate financial incentives that supports in releasing the congestion over critical lines. Distributed generation implementing wind plant as renewable independent power producer (RIPP) has also been included in order to reduce the load curtailment of responsive customers to manage transmission congestion. The proposed incentive-based demand response and distributed generation approach of CM, has been framed with various strategies employing different thermal limits over transmission lines and has resulted into significant reduction in congestion and in-turn improvement of transmission reliability margin. Diversity has been obtained in multiobjective optimization by taking two and three objective functions, respectively (minimization of overall operational cost, CO2 emission, and line loading). The by-products of the proposed algorithm for multiobjective optimization are minimized demand reduction, optimum size, and location of DG. To examine the proposed approach, it has been implemented on IEEE 30-bus system and a bigger power system IEEE 118-bus system; as well as the proposed technique of MOSSA has been compared and found better than reported methods and two other meta heuristic algorithms (multiobjective modified sperm swarm optimization and multiobjective adoptive rat swarm optimization).

Independent power producers and deregulation in an island based small electricity system: The case of Papua New Guinea

The small island economy of Papua New Guinea (PNG) is facing severe electricity shortages and is therefore turning to implementing broader power sector reforms as a vehicle to attract private capital and investments in electricity generation. This study, based on a case-study approach, revisits the reform progress and plans in the electricity sector of PNG alongside the development and integration of IPPs in its small power system. Lessons of reform experiences and IPPs integration are drawn from three other smaller systems of Nepal, Nicaragua and the Northern Territory of Australia including stakeholder consultations, which includes two IPPs of PNG. We find a widening gap between reform ‘theory’ and ‘practice’ in the PNG power sector. Cost reflective pricing is implemented while cost recovery is never achieved by the vertically integrated state-owned utility and the insolvency of this state-owned single buyer poses the greatest perceived revenue risk to the IPPs. This lack of revenue reimbursement to the IPPs by the single buyer is a barrier towards attracting private capital into electricity generation. We recommend that strong political will and strengthening of institutional arrangements are urgent reform measures to attract private capital in power generation as political instability continue.

Wholesale electricity market economics of solar generation in Israel

We use a two-stage model to determine the equilibrium capacities, generation levels, and prices of a wholesale electricity market in which independent power producers (IPPs) use natural gas-fired (NG) and photovoltaic (PV) technologies. PV's effective capacity is high during midday but low in other daytime hours. Applied to Israel's stylized electricity market in 2030, our model finds NG and PV are necessary to meet Israel's electricity demands; NG mitigates daytime price spikes and enhances consumer welfare; NG IPPs are profitable; and PV IPPs may be unprofitable, potentially requiring government support to aid Israel's achievement of a clean and sustainable future.

A Polyhedral Study on Fuel-Constrained Unit Commitment

The electricity production of a thermal generator is often constrained by the available fuel supply. These fuel constraints impose a maximum bound on the energy output over multiple time periods. Fuel constraints are increasingly important in electricity markets because of two main reasons. First, as more natural gas-fired generators join the deregulated market, there is often competition for natural gas supply from other sectors (e.g., residential and manufacturing heating). Second, as more environmental and emission regulations are being placed on fossil fuel-fired generators, fuel supply is becoming more limited. However, there are few studies that consider the fuel constraints in the unit commitment problem from the perspective of computational analysis. To address the challenge faced by an independent power producer with a limited fuel supply, we study a fuel-constrained self-scheduling unit commitment (FSUC) problem where the production decisions are coupled across multiple time periods. We provide a complexity analysis of the FSUC problem and conduct a comprehensive polyhedral study by deriving strong valid inequalities. We demonstrate the effectiveness of our proposed inequalities as cutting planes in solving various multistage stochastic FSUC problems. History: Accepted by Pascal Van Hentenryck, Area Editor for Computational Modeling: Methods & Analysis. Funding: K. Pan was supported in part by the Research Grants Council of Hong Kong [Grant 15501920]. F. Qiu was supported in part by the U.S. Department of Energy Advanced Grid Modeling Program [Grant DE-OE0000875]. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplementary Information [ https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2022.1235 ] or is available from the IJOC GitHub software repository ( https://github.com/INFORMSJoC ) at [ http://dx.doi.org/10.5281/zenodo.6896199 ].

Development of a probabilistic short-term voltage quality assessment method with the weak point detection capability through the dynamic analyses

The proliferation of power electronics-based sources and equipment in low voltage to high voltage applications reshapes the dynamic behavior of power system networks, leading to certain voltage quality vulnerabilities for industrial customers and independent power producers. The root causes of most voltage quality problems are related to power system faults which may trigger voltage dips, voltage swells, and interruptions. In-depth stochastic modeling combined with advanced power system simulations and statistical validation is required to foresee the effects of these events on the network users. Therefore, a holistic method was proposed in this paper that utilizes reliability parameters in the context of the novel Monte Carlo-based fault creation approach. This method incorporates the input data from an extensive literature survey and real-life measurements. The probabilistic fault events are simulated in an environment where the protection system – dynamics interactions are considered. A modified IEEE test system was developed to introduce unconventional sources into the conventional test grid. A python script was developed to implement the algorithms into the power system analysis tool. Also, several voltage quality indices were introduced which are based on international standards. 30 Monte Carlo repetitions of a 5-year simulation period were performed (150 years Monte Carlo simulations), leading to a total number of 4410 fault cases for each network scenario. The results of the Monte-Carlo simulations were used to find the weak points of the network under five different operation and design scenarios with several statistical significance tests.

Probing the Financial Sustainability of Eskom’s Open Cycle Gas Turbines (OCGTs) Utilisation (2018–2021)

Contributing to achieving sustainability in South Africa’s energy sector, this study probes financial sustainability and its relationship to the environmental sustainability of Eskom. This is because, over the past three financial years (FY2018–2019 to FY2020–2021) of Eskom’s generating plants’ performance, the energy availability factor (EAF) has taken a deep dive, reaching an extremely low generation availability year-end performance of 64.2%, translating to approximately an average of 29,800 MW available generation capacity out of a nominal generation capacity of 46,466 MW in FY2020–2021. Therefore, the study employed a quantitative research methodology, where the relevant financial records were analysed, and the necessary energy calculations made using descriptive analysis in Microsoft Excel. The findings show that the volumes (GWh) produced by the OCGTs during this period far exceed the regulatory approved volumes, thus attracting substantial costs, amounting to ZAR 25.9 bn instead of ZAR 8.9 bn, that could have been spent on the OCGTs if the level of efficiency achieved in FY2016–2017 and FY2017–2018 was maintained. The analysis also revealed that the OCGTs’ long-term financial and environmental sustainability could be achieved through switching from diesel to natural gas, thus resulting in lower fuel costs and lower emissions. Further, potential savings of approximately ZAR 27 bn (excluding capital expenditure) at a 10% load factor can be realised over a ten-year period when the natural gas price is sitting at ZAR 85/GJ (minimum). Finally, in order to attain financial and environmental sustainability, it is recommended that both Eskom’s and the independent power producers’ (IPPs) OCGTs must switch fuel from diesel to natural gas and be run at a 10% load factor, allowing the OCGTs to be run as mid-merit generators.

Indonesia's deregulated generation expansion planning model based on mixed strategy game theory model for determining the optimal power purchase agreement

—Obtaining the optimal power purchase agreements (PPA) in deregulated generation expansion planning is crucial. A lower PPA provided by the utility results in the independent power producer (IPP) becoming disinterested in investment. On the other hand, a higher PPA increases the government's financial burden. Therefore, this study proposes a generation expansion planning model that considers the deregulated market and PPA determination. A game theory based on a mixed strategy method and bi-level model is used in this research. To obtain the PPA optimum value, a multi-scenario analysis is conducted by changing the PPAs from 25% to 100% of the generation cost. The proposed model is applied to the Bangka Belitung power system. The results of the multi-scenario analysis show that the optimum PPA is 30% of Bangka Belitung's generation cost. This PPA creates an optimum generation expansion planning with a levelized electricity cost of 6.009 cents USD/kWh. However, the utility cannot offer a PPA of less than 30% of the generation cost because the private sector is not interested in investing. Therefore, it forces the utility to rent diesel power plants and increases the LCOE to 8.629 cents USD/kWh.

Implementation of a Multiterminal Line Commutated Converter HVDC Scheme with Auxiliary Controller on South Africa’s 765 kV Corridor

The deployment of a 765-kV transmission line on Eskom’s South African Grid marks the beginning of a new era in power industries. The integration of renewable energies by independent power producers (IPPs) leads to an infrastructural change in the stability performance of the entire grid. These developments are expected to bring about a multiterminal direct current (MTDC) system for practical implementation on this grid. Therefore, this study focuses on the dynamic response of the South African transmission grid during a system disturbance. In the carrying out of this study, the South African grid was modeled on PSCAD, and its performance was evaluated. The impact of the MTDC link on the grid’s interarea oscillation was also investigated. An additional current order controller for the MTDC link was developed, and its impact on the MTDC power transfer was analyzed. The results show a better system performance and reduced interarea power swings with the inclusion of the MTDC link.

Privatisation of Power Generation in Malaysia: Impact on the Entry of Malays into Power Business

This paper reviews Malaysia’s experience in privatisation in power generation from the first half of the 1990s and the role it played in promoting Malay entry into business. In the pre-1949 period, privately-owned independent power producers and distributors (IPPs and Ds) were the dominant players. The government-owned integrated power utility, Tenaga Nasional Berhad (TNB), became a monopoly only since 1976. TNB’s finances were strained during the Asian Financial Crisis (AFC) period, but contracts were honoured despite strong calls for renegotiation of power purchase agreements (PPA). With the open tender era from 2012, the PPA terms have become very competitive. However, as TNB can continue to bid, this has not made for a level playing field. With competition and fall in interest rate, there has been a significant decline in internal rate of returns (IRRs). Guaranteed off-take enabled some concessionaires to still earn a good equity IRR through aggressive gearing. Development of a more active and liquid bond market has played a key role in privatisation.

Food to Grid: Developing a Multi-Value renewable energy investment ecosystem

The paper is focused on building a multi-source small-scale facility that shall be focused on increasing the Renewable Energy Sources share into the grid and at the same time meet the energy, and fresh food needs of the small community that shall operate. The developed facility that shall be utilised is introducing, in practice, a sustainable Energy-Food nexus plan that can be implemented and put into action by the independent power producers and municipalities, meeting also the goal of supporting the grid (a Food to Grid approach). A case study was tested, and it was found that a scheme that couples the curtailed power with a potential mass deployment of vertical farms is beyond sustainable and even with very low marginal price-earnings and the minimum price offered for vertical farms, under specific scenarios can have a full payback in 14 years as an investment. However, in the average optimal case, the investors can get their investments back in 7 years, with an internal rate of return of 17%.

A Novel Approach to Predict Transformer Temperature Rise under Harmonic Load Current Conditions

In South Africa, distribution transformers (DTs) facilitating solar photovoltaic applications represent the highest percentage of total ownership cost investment for independent power producers (IPPs). One of the most indispensable variables that regulate DTs’ operational life span is the hotspot temperature. The prevailing analytical approaches designated to guesstimate the transformer thermal necessities were fathered in accordance with the conservative foundation that an electrical transformer is prone to uniform mean daily and monthly peak loads. In order to appropriately puzzle out the transformer thermal necessities, the formation of a more detailed thermal model that operates with real-time contorted cyclic loading, ambient air temperature, and the intrinsic characteristics of the transformer in-service losses is required. In the current work, various regression models are proposed for the modification of the top-oil formula and the hotspot temperature formula in the IEEE loading guide standard to replicate the real harmonic load currents (HLCs) and the fluctuating ambient air temperature (AT) on an hourly and daily basis. The proposed thermal model is examined in various transformers case studies, in which the computed outcomes produce an error margin of no more than 3% throughout all test cases when compared to the measured data.

STRATEGIC ANALYSIS OF THE NEPAL ELECTRICITY AUTHORITY: A SWOT-AHP ANALYSIS BASED ON STAKEHOLDERS’ PERCEPTIONS

The Strength, Weakness, Opportunities & Threat (SWOT) analysis of an organization is a crucial method for assessing the most relevant internal (Strengths and Weaknesses) and external (Opportunities and Threats) factors affecting the organization. The purpose of this study is to rank the identified factors of strengths, weaknesses, opportunities and threats of the Nepal Electricity Authority (NEA), an undertaking of the Government of Nepal mandated for generation, transmission, and distribution of electricity throughout the country. This paper utilizes the Analytical Hierarchy Process (AHP), a Multicriteria Decision Making (MCDM) technique, to rank the SWOT factors for NEA strategic planning. The AHP method in combination with a SWOT analysis was utilized to conduct pairwise comparison among the identified factors in order to prioritize them using Eigen values. A structured questionnaire was used to collect data from the experts of the NEA, independent power producers, the Ministry of Energy, Water Resources and Irrigation, energy companies, and donor agencies. The study reveals that the monopoly business nature, the huge internal demand for energy and a nationwide electricity distribution network are the main strengths of the NEA whereas an inability to absorb all energy procured through “take or pay” contracts and an insufficient transmission and distribution network are the main threats and weaknesses. Similarly, long-term growth of electricity demand, trade of power and energy banking are the identified opportunities. The findings of the study will help the organization utilize its strengths and opportunities, tackle its weaknesses, and mitigate the threats.

Cost-benefit analysis of wind power integra-tion in distribution networks

The capacity of power generation note needs to be increased globally, owing to population growth and industrial revolution. The conventional power plant across the world is inadequate to satisfy growing power demand. By optimally sizing and designing the clusters of renewable energy sources such as wind, microgrid operators can economically and environmentally sustainably provide a clean power solution that can increase the supply of electricity. Wind power (WP) generation can be utilised to reduce the stress on the power plants by minimising the peak demands in constrained distribution networks. Benefits of WP include increased energy revenue, increased system reliability, investment deferment, power loss reduction, and environmental pollution reduction. These will strengthen the performance of the power system and bring economic value to society. Moreover, many challenges are considered when integrating WP into the distribution system. These include protection device miscoordination, fundamental changes in the network topology, transmission congestion, bidirectional power flow, and harmonic current injections. In this paper, the economic cost and benefit analysis of optimal integration of WP into the distribution networks is investigated through a multi-objective analytical method. The aim is to see whether investment in the WP project is economically profitable and technically viable in the distribution system. The results obtained from the study can be utilised by power system operators, planners and designers as criteria to use WP for stimulating economic development and industrial revolution and can allow independent power producers to make appropriate investment decisions.

Analisis Pengaruh Perubahan Tekanan Vakum Kondensor Terhadap Heat Rate Turbin Di PLTU Moramo Sebelum dan Sesudah Perawatan

PLTU Moramo is one of the Independent Power Producers (IPP) that supplies electricity to PT PLN. PLTU Moramo make use of turbine-generator with an installed capacity of 2x50 MW Steam Turbine - Full Condensing. PLTU Moramo Unit 1 experienced an increase in the condenser vacuum value after routine maintenance, the increase in the vacuum value affected to the heat rate and efficiency of the steam turbine cycle. The research conducted is to analyzes the effect of changes in the value of the condenser vacuum on the heat rate and efficiency of the steam turbine cycle by using a thermodynamic analysis approach and energy input-output methods. Data analysis uses actual parameters taken from the Distributed Control System (DCS) during normal operation. The results obtained in this study indicate that an increase in the condenser vacuum value affects the heat rate and efficiency of the steam turbine cycle, an increase in the vacuum value of -1 kPa results in a decrease in the average turbine heat rate of 57,673 kJ/kWh for a load of 40 MW Net and 93,575 kJ/ kWh for 50 MW Net load. Meanwhile, the average value of the steam turbine cycle efficiency increased by 0.37% for a load of 40 MW Net and 2.19% for 50 MW Net. Keywords: heat rate, efficiency, PLTU, vacuum

Integrated Stochastic Optimal Self-Scheduling for Two-Settlement Electricity Markets

The complexity of current electricity wholesale markets and the increased volatility of electricity prices because of the intermittent nature of renewable generation make independent power producers (IPPs) face significant challenges to submit offers. This challenge increases for those owning traditional coal-fired thermal generators and renewable generation. In this paper, an integrated stochastic optimal strategy is proposed for an IPP using the self-scheduling approach through its participation in both day-ahead and real-time markets (i.e., two-settlement electricity markets) as a price taker. In the proposed approach, the IPP submits an offer for all periods to the day-ahead market for which a multistage stochastic programming setting is explored for providing real-time market offers for each period as a recourse. This strategy has the advantage of achieving overall maximum profits for both markets in the given operational time horizon. Such a strategy is theoretically proved to be more profitable than alternative self-scheduling strategies as it takes advantage of the continuously realized scenario information of the renewable energy output and real-time prices over time. To improve computational efficiency, we explore polyhedral structures to derive strong valid inequalities, including convex hull descriptions for certain special cases, thus strengthening the formulation of our proposed model. Polynomial-time separation algorithms are then established for the derived exponential-sized inequalities to speed up the branch-and-cut process. Finally, both numerical and real case studies demonstrate the potential of the proposed strategy. Summary of Contribution: This paper develops innovative models and methods to study a family of practically important problems via the interactions of operations research and computing. Specifically, this paper provides in-depth analyses of innovative stochastic optimization modeling approaches and develops computationally efficient polyhedral results. The paper also verifies the effectiveness of proposed analyses via extensive computing experiments.

Mitigating the impact of high-capacity dispatchable distributed generation on reconfigurable distribution networks with step voltage regulators: A real case study on voltage issues

This paper investigates and discusses voltage issues currently faced by engineers from a Brazilian utility in the high-capacity dispatchable distributed generation (DG) interconnection planning study on a real reconfigurable distribution network with cascaded step voltage regulators (SVRs). Based on this investigation, this paper proposes an optimal rescheduling approach applied to high-capacity dispatchable DG considering two additional technical constraints to the optimization problem for mitigating voltage issues, such as over/undervoltage violations and SVR runaway, while still allowing network reconfiguration schemes and benefiting the independent power producer (IPP). With this approach, the active power supplied by the IPP's DG is adjusted throughout the day with respect to the feeder load forecast, avoiding reverse power flow situations on SVRs and ensuring suitable control operation on reconfigurable distribution networks. The problem is formulated as a constrained optimization and solved through the primal-dual interior point technique. Simulation results on a real Brazilian reconfigurable distribution network demonstrate that the proposed method is effective to mitigate the identified voltage issues without affecting network reconfiguration operations and the weekly average active power injected by the DG.

Sustainable hydroelectric power project planning under socio-economic and environmental concerns using Index based approach

PurposeThis study aims to identify and gauge the sustainability indicators (SUSIs) for sustainable Hydroelectric Power (HEP) project development. It examines major SUSIs under the social, economic and environmental (SEE) fronts and categorizes them under push and pull impacts which helps to identify challenges and opportunities associated with projects. Additionally, the study calculates an empirical sustainability index (SI) to assess the sustainability level of HEP. Finally, the study suggests mitigation measures across stakeholders, which will optimize government/developer/investor investments.Design/methodology/approachThis paper examines the interaction of sustainable HEP development with SUSIs using Uttarakhand as a study area. Additionally, SI has been developed quantitatively. For the indicator classification, the authors conducted a literature review and secondary survey of all affected parties, including investors, developers, NGOs and villagers. The fuzzy logic theory (FLT) is used to determine the SI of the study area and classify projects in their level of sustainability. On the basis of expert opinion and literature review, mitigation measures are proposed across stakeholders.FindingsThe authors found that there is a mixed effect of SUSIs on HEP development across various projects in Uttarakhand. Furthermore, the authors suggest that index-based assessment and planned collaboration play a significant role in sustainable HEP development. Mitigation measures should be suggested to all affected stakeholders based on specific project issues, i.e. collaborations, training, public awareness campaigns, and initiatives by the government that would improve sustainability conditions.Research limitations/implicationsIn addition to supporting the ongoing and upcoming initiatives launched by the Government of India, including the Green Energy Corridor, independent power producers (IPPs); and the India-Renewable Resources Development Project with IDA and participates in Net zero target.Practical implicationsThe structured, sustainable HEP planning suggested in the study will help to conserve society, economy, save resources and in parallel reduce the cost and time of developers and policymakers. This will also help to improve the socioeconomic status of the villagers and prolong the life of the project.Originality/valueThe innovative SI-based push-pull approach identifies a sustainable HEP project planning.

Techno-economic analysis to develop the first wind farm in the Egyptian western desert at Elkharga Oasis

Abstract During the past few years, Egypt has increased the share of electricity generation from renewable energy sources to achieve the renewable-energy strategy. The Egyptian Ministry of Electricity and Renewable Energy has set an ambitious target to increase the share of renewable energy among the total energy mix to be 20% by 2022 and 42% by 2035. This target will be achieved using several approved policies such as feed-in tariffs, build–own–operate and independent power producers under a merchant scheme. This paper presents a full analysis of wind-potential characteristics at Elkharga Oasis in Egypt based on an actual wind-measurement campaign taken by a met mast at two height levels of 10 and 25 m, respectively. The measurements show an average annual wind speed of 5.72 m/s at 10-m height and 6.53 m/s at >25-m height. The estimated wind speed, however, is 8.38 m/s at 120 m, which is technically convenient to generate electricity from wind energy. In this paper, the wind potential in the area is assessed using the statistical method of the Weibull probability density function. The different methods to estimate the Weibull distribution parameters are presented and the relevant accuracy is verified based on the root mean square error. A techno-economic assessment and selection of the optimal wind-turbine size with ideal micro-sitings are performed using the software package windPRO. Different cases of study for three typical wind-turbine models with various rotor diameters, power capacity, layout configuration and annual yield are assessed at the site. The selection of the most convenient wind turbine is determined based on the IEC 61400 standard criteria and the turbine that produces the lowest levelized cost of electricity.

Implementation of 100% Electric Vehicle in Bali with the Supply of Potential Independent Solar Energy

<p class="02abstracttext">Electrical vehicle is the future of transportation. This thesis is about how to transform the usage of fossil fuel vehicle to electrical vehicle in Bali. Bali is an island with the longest distance from one of its districts to Denpasar city is 95,6 km. This distance is reachable by the common electrical vehicle that available in the market now. The usage of the electrical vehicle requires good development and planning, otherwise it will cause problem for the electrical systems. The consumption of electrical energy will increase. In 2019, Bali used 5,908 GWh electricity in a year. And if all the 2 wheels and 4-wheels vehicles now are electrical vehicle, it will require extra 2,823 GWh per year. It will impact the planning of power generation in Bali.Another challenge for the electrical systems is the duck curve problem. The habit of the user charges their vehicle will also impact the daily load curve of an electrical systems. If all the two wheels and four wheels vehicles now are electrical vehicle, and all users conduct the charging at the same time in 4 hours duration, the load will increase about 1,934 GW. The practical and applicable solution is the independent power producer concept by the solar PV. If every electric vehicle user installs the solar PV for their electrical vehicle consumption, this will solve all the problem.</p>