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A sample risk analysis has been carried out for a typical German urban utility in a 10-kV network group fed by one substation (firm capacity 40 MVA). The new approach of risk analysis in electrical networks combines one of the results of reliability studies (components contribution to expected-energy-not-supplied-EENS) with the input data (components failure rate and repair time) and enables an assessment...
This paper evaluates the correlation between failures and power consumption for a distribution systems operator. This is done in order to scrutinize whether the commonly used assumptions of constant failure rate and constant power consumption is reasonable to use for reliability calculations. The studied entity is energy not supplied, which is assumed to be a good estimate of how customer interruption...
The risk assessment method for power system standard evaluation in regard to generation and transmission capacities adequacy for the perspective 5 and 10 years period under the information uncertainly conditions is being analysed in the paper. The tool of the method is the programme LDM-T&G'05 (Latvian Dynamic Model for Transmission and Generation). The programme provides the opportunity to perform...
Harmonics in rail transportation systems are an important design aspect. The overall load in these systems consists of a few large traction motors, often supplied by thyristor controlled choppers or PWM converters. These converters produce high levels of harmonic currents, which may extend into the kHz range. Recognizing harmonic problems in an early stage of development is important in order to avoid...
The objectives of the transmission expansion planning have changed owing to restructuring of power sector. Transmission systems in the deregulated environment have to provide non-discriminatory access to allow competition, robust transmission network against uncertainties etc. Uncertainties are handled by both deterministic and non-deterministic approaches. Non-deterministic methods consider many...
Wood poles are widely used for overhead distribution system, and constitute an important component of utilities' assets. Since they are usually designed based on deterministic approach stipulated by utility's own design practice or relevant nation standard, the reliabilities achieved are often unknown. This paper presents a study on structural reliability of distribution wood poles selected according...
The importance and necessity of conducting studies on grid reliability evaluation have been increasingly important in recent years due to the number of black-out events occurring through in the world. Quantity evaluation of transmission system reliability is very important in a competitive electricity environment. The reason is that the successful operation of electric power under a deregulated electricity...
This paper proposes a maintenance strategy for electrical equipment in a chemical plant from the reliability perspective. Two types of the plant downtime cost are modeled. One is the planned downtime cost consisting of opportunity cost and scheduled maintenance cost. The other is the unplanned downtime cost consisting of opportunity cost, plant recovery operation cost, and damage of material loss...
The paper presents a new fast, reliable and relatively simple decoupled quadratic load flow (DQLF) algorithm for Q-adjustments in power flow solutions. Q-adjusted solutions are inevitable for reactive power planning and management studies. For solving power flow problems, the fast decoupled load flow (FDLF) is probably the most popular, because of its efficiency. But for Q-adjusted studies, the matrix...
Power system equipments are normally designed for a specific system and load situation. This situation could change significantly as a result of the system expansion or aging. Among the system equipments, circuit breakers are more sensitive to the system expansion and they must be able to isolate the faulty components if a fault occurs. As the system load increases in the future, the power network...
Probabilistic reliability calculations are widely spread for the design of distribution networks. This paper deals with the application of probabilistic reliability calculations to assess the impact of the grid connection on the overall reliability of wind farm power production. A characteristic of the grid connections of offshore wind farms is almost no redundancy. The main intention of the presented...
This paper demonstrates two application examples of probabilistic risk assessment (PRA) in power system operations. In the first example, a risk based method is proposed to take the uncertainty of contingency occurrence and impacts into account to provide an essential set of contingency cases for a transient stability special protection system (SPS) implementation. In the second example, an approach...
This paper illustrates to determinate how much is the reasonable capacity of tie lines in view point of probabilistic reliability in the North East Asia by using the tie line constrained equivalent assisting generator model (TEAG), which has been already developed by authors. A reliability evaluation program, it is named, NEAREL, based on the TEAG model was made. The reliability evaluation results...
This paper presents a method of deciding the best placement of additional generation for long term generation adequacy planning in multi-area power systems. The approach uses evaluation of the prospective scenarios of additional generation, and tie-lines. Maximum number of additional generators in each area will be determined from the cost with respect to overall budget constraint. The selection criterion...
Making the most of the load capacity of the existing transmission and distribution system is now of great importance. The real value of the load capacity of an overhead line depends significantly on actual weather conditions. The method of line rating using the real risk analysis is described in the paper. The overhead line ampacity calculated using the risk evaluation has different values in comparison...
Circuit-breakers are one of the most important equipment in power systems. They serve as interrupting devices which interrupt the operating and short-circuit currents. In the past, electrical stresses of circuit-breakers are determined mainly by operating currents, short-circuit currents and switching operation. In addition, the number of faults on overhead lines which circuit-breakers have to be...
A wind farm is a collection of wind turbines built in an area to provide electricity. Wind power is a renewable energy resource and an alternative to nonrenewable fossil fuels. In this paper impact of wind farm in power system reliability is investigated and a new procedure for reliability assessment of power systems with wind farm in HLII is proposed. In proposed procedure, a wind farm is given as...
This paper proposes the estimation results of the stochastic characteristics of harmonic and flicker for an AC and a DC electric arc furnace feeders. These characteristics include stationarity, normality and correlation. Besides, the statistic probability was assessed, too. The estimation and the assessment are implemented by a PC-based virtual instrumentation system. The results show that (1) most...
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