SES reliability calculation - DBE, Drawings

Contents

Introduction

1 Analysis of existing methods for improving SES reliability

1.1 Overview of existing EPS reliability models

1.2 Methods of improving the reliability of Russian EPS

1.3 Economic aspects of EPS reliability

1.4 Review of regulatory documents on reliability

2 Initial data

3 Analytical method of calculation of reliability of electrical installations

3.1 Short-term and long-term substation shutdown

3.2 Short-term and long-term substation shutdown

3.3 Short-term and long-term substation shutdown

4 Calculation of damage from underutilization of energy

5 Logic-probabilistic method of power supply reliability calculation with

using the fault tree

6 Possible Ways to Improve Reliability

6.1 Short-term and long-term substation shutdown

Conclusion

List of sources used

introduction

Research on the reliability of EES was developed after a systemic accident in November 1965 in North America, when large areas in North America and Eastern Canada were completely without power for several hours. As a result of this accident in the United States, it was decided to form the National Electricity Reliability Council.

In our country, the beginning of systematic research and the formation of a domestic scientific school on the reliability of EES also dates back to the 60s of the last century. The work of many scientists and specialists created a fundamental theory of the reliability of EES, which has been recognized in our country and abroad and has found application in the practice of designing, operating and managing EES.

The processes of reform in the electric power industry entailed significant changes in the legal framework and general principles of economic relations in the field of electricity turnover, as well as structural changes with the formation of electricity market entities as EEC subsystems. At the same time, issues of reliability of performing their functions by market entities acquired increased relevance especially after the well-known Moscow accident on May 2425, 2005. The Federal Law "On Electric Power Industry" requires the establishment of economically balanced relations between all entities of the electric power market on the basis of reliability fees and full compensation of losses due to the unreliability of electricity supply. The Concept of Ensuring Reliability in the Electric Power Industry, approved in 2004 by RAO UES of Russia, proclaimed the thesis: "the reliability of electricity supply to consumers in market conditions becomes a product with an appropriate price and the subject of contractual relations between energy market entities sold through market services." The above provisions demonstrate the legality of classifying reliability issues as innovative activities aimed at commercializing the accumulated knowledge, technologies and equipment.

The main objectives of the course project are a more in-depth study of the material in the course "Reliability of electric power systems," obtaining skills in calculating the reliability of electric power systems and networks using analytical and logic-probabilistic methods with the construction of a fault tree.

Overview of existing EPS reliability models

MEXICO Model (EDF, France). This model, which has been working on for more than two decades, is based on statistical modeling and does not take into account chronology when modeling over time. With this model, you can explore diagrams of up to 500 nodes and up to 1200 links. The individual states of the system are simulated randomly according to the availability factors of the generating and transmitting equipment. For each such state, at a given level of consumption, using the solution of the linear programming problem, generating powers and flows in lines are determined that minimize the sum of current costs and damage from power failure when taking into account electrical equations in the network in the DC idealization. Then the results of all the considered states are averaged and various reliability indicators are calculated.

SICRET model (ENEL, Italy). This model, which has also been working on for about three decades, uses the same approach as in MEXICO, but there are a number of differences. So, it allows you to consider AC and DC networks. When analyzing an individual condition, a compromise is made between reliability and cost-effectiveness by minimizing the reduced costs.

COMREL (University of Saskatchewan, Canada). This model is a sample of using the analytical method. One of three approaches can be used to analyze each state: a linear stream model, a DC idealization model, and a fast split flow method. Count time is reduced by limiting the upper level of simultaneous failures and non-recalculation of states whose probability is lower than the specified limit.

ORION Model (Komi Research Center). This model is based on a combined analyticostatistic method. The power deficit calculation routine takes into account only the first Kirchhoff law, and a dual simplex method is used to estimate the individual state, in which the results of calculating the previous state are taken as the initial approximation for each next state. The advantage is that the determination of the initial plan in a dual staging is made without difficulty (in setting the problem, the coefficients of linear forms are non-negative and equal to 1).

Model POTOK-3 (SEI SO RAS). This model is based on a consistent method of statistical testing. A chronological modeling principle is used, which allows you to take into account the possibility of the influence of the previous state on the subsequent one. The program for calculating capacity deficits also takes into account only the first Kirchhof law.

To estimate the minimum deficit in the system, two models are used: the first uses only balance equations and is based on streaming algorithms, and the problem of ambiguity is solved using a special problem; the second model is based on the network equations in DC idealization and the method of internal points combined with the relaxation method is used to solve it. Very actively in "STREAM" the FordaFalkersona method (stream algorithms) is used.

AMBER model (SEI). Generation of design states in this model is carried out by the method of statistical tests on the basis of analytically obtained functions of distribution of states of generating capacities and loads taking into account their random oscillations in nodes, as well as power transmission lines for communications. System equipment state distribution series and characteristic daily load schedules are the initial information for system state determination. To determine the reliability indicators of the system in the initial design, it was necessary to analyze only the states characterized by the presence of a power shortage. The algorithm also provided for the possibility of maximum elimination of calculations of deficient states. The main idea of ​ ​ the algorithm was to cycle through all possible states of the system ordered by "severity" in such a way that each subsequent state would be easier in the sense of deficit. In subsequent modifications of YANTAR, not only the first BOR model is used, but all the rest .

1.2 Review of existing models of reliability of EPS equipment and analysis of its damage

When solving EPS reliability problems, reliability determination methods such as calculations and experiments are widely used, which involve modeling the reliability properties of equipment. In this regard, equipment models that can be used in one form or another in solving design and operational tasks are discussed below.

• Reliability models of main power equipment of electrical networks

Power equipment refers to equipment connected directly to the power and energy flow transmission circuits.

Air and cable power lines

are recoverable objects that can be in operable state, fail, go into inoperable state, be repaired and, after restoration, return to operable state. Failure here refers to any event that has occurred on the line, which leads to the need to turn it off. In addition, these objects at some points are quickly disconnected and go into a non-working state associated with preventive repairs (capital, current). Thus, a power line can be modeled by an element that has three states: operable, inoperable emergency (hereinafter simply, inoperable or emergency), inoperable planned (hereinafter - scheduled repair)

Two types of failures are characteristic of power lines: stable ones, which lead to the need for its disconnection and emergency recovery operations, and unstable ones, which are eliminated by disconnection of the line and its re-actuation without emergency recovery operations. The break time in the latter case depends on how the line is re-activated. With automatic re-start, this time is from tenths of a second to a few seconds, and when switched on by operational personnel - up to several minutes. In connection with the above, the main parameters of such an element are: frequency of stable and unstable failures; average duration of emergency repair (after steady failure); average duration of scheduled repair; Frequency of scheduled outages. In a number of tasks, it is possible to detail the duration of planned repairs and their frequencies for capital and current ones.

Transmission line failure rates usually depend on the length of the line. In most cases, as failure statistics show, this dependency is linear. Therefore, when the reliability indicators of the lines of a certain class are generalized, it is convenient to use the specific failure rate indicators, relating the full frequency of the corresponding failures to the length of the line. Other indicators depend to a small extent on the length of the line, which is due to the accepted forms of organization of repair and maintenance of electrical networks. Therefore, in practical calculations, these indicators can be considered independent of the length of the line.

An important parameter of the line that significantly affects the reliability of the network is its capacity. In the model of the line under consideration, it was assumed that failures lead to a complete loss of its capacity (complete disconnection of the line). In some cases, the failure of some elements of the line may not lead to its complete disconnection, but only, for example, to the disconnection of one phase. If the line is allowed to operate in a non-phase mode, then, as a rule, its capacity is reduced. In this case, the line model should provide for a partial failure and a partial inoperable state with corresponding reliability indicators. It should also be noted that for individual lines, indicators such as failure rates can significantly depend on the seasons of the year and hours of the day.

The single-chain line model was discussed above. If the line is multi-chain, that is, individual circuits are structurally placed on the same supports and thereby interconnected mechanically, electrical strength, etc., then the model of such a line can be built in two ways: or as a model of an object with many partial failures, each of which, together with the state into which the object passes after failure, is characterized by a set of indicators similar to the considered indicators of single-chain lines; either as a collection of single-chain models, but no longer independent objects, but dependent ones. In the second case, the reliability indicators of joint failures and downtime are added to the reliability indicators of individual circuits.

Transformer (autotransformer)

is a recoverable object that can be in a functional state, fail and go into an inoperable emergency state, recover and return to a functional state. In addition, at certain points it is quickly disconnected for preventive repairs or withdrawal to the reserve. Failure here refers to any damage in the transformer, leading to the need to turn it off. Thus, the transformer can, like the line, be modeled by an element having three states: operable, inoperable and scheduled repair. The main parameters of such an element are: failure rate; average duration of emergency repair; average duration of scheduled repair; Frequency of scheduled outages. Here, as well as for lines, in a number of tasks it is possible to detail planned repairs for capital and current ones.

The reliability indicators of transformers depend little on those factors that affect the reliability indicators of the lines. It can be noted that for all three-phase transformers, failures lead to a complete shutdown of the object. For transformers consisting of a group of single-phase (if incomplete mode is allowed), the failure may be partial.

Switch

is one of the complex objects of the electrical network. As well as a power transmission line and a transformer, the switch is a recoverable object that can be in three states: operable, inoperable and in planned repair. The switch has various types of failures, which can lead to various consequences in the system. Consider the possible damages in the switch and their consequences. Damage of type 1 (for example, breakdown of the insulation of the left column) can be accompanied by their localization on one side by a switch or adjacent switching devices. On the other hand, these damages are localized only by adjacent switching sets. Thus, the type 1 damages in question can cause two types of failures:

- leading to the necessity of operation of all adjacent switching devices on only one side (left) of the switch (failure of type 1); - leading to the necessity of operation of all adjacent switching devices on both sides of the switch (failure of type 3).

Damage of type 2 is similar in its consequences to damage of type 1, only the side changes (failure of type 2).

Damage of type 3 (for example, a switch drop, shutdown of the disconnecting chamber, etc.) leads to a failure, as a result of which the operation of all adjacent switching devices is required (failure of type 3).

In addition, there are cases when as a result of some problems there is a spontaneous disconnection of the switch (circuit break), which is not accompanied by the disconnection of adjacent switching devices, the so-called false operation (failure of type 4).

The types of failures considered are usually independent and are similar in nature to the failures of power lines and transformers. In addition, the switches have actuation failures at the appearance of the demand for both shutdown (failure of type 5) and actuation (failure of type 6), for example, at automatic reserve entry (ALT). If the first types of failures are independent, then the latter are conditioned by already arising requirements, which are usually associated with failures of other network elements, which makes them dependent.

In connection with the stated main parameters of the circuit breaker reliability are: failure frequency of types 1, 2, 3 and 4; probability of failure of actuation to demand (relative failure rate) of shutdown and actuation; average duration of emergency repair; average duration of scheduled repair; Frequency of scheduled outages frequency of operational switching. Reliability indicator - the probability of response to the shutdown requirement, in turn, can be divided into the probability of failure during emergency outages (overcurrent) and during operational switching.

The considered switch model is the most complete. In practical calculations, individual indicators can be insignificant and can be neglected. The most commonly used circuit breaker model 2 includes only two indicators of failures: the frequency of failures of type 3 (failure frequency, in static state) and the probability of failure of response to the demand to shut down overcurrent. At the same time, 3 includes failures that occur during operational switching, taken into account based on average switching frequencies. The coarse one is Model 3, which represents a switch with only one type of failure that coincides with a failure of Type 3. The failure rate indicator at that includes averaged all failures with such consequences.

Separator

functionally from the position of reliability performs the same role in the network as a switch, therefore it can be modeled in the same way as a switch.

Disconnector,

playing an independent role of the switching apparatus in the network, has a model similar to that of the switch.

Switchgear buses

have a model similar to the line model.

• Models of the main elements of the EPS generating subsystem

The main element of this subsystem is a generating unit, which can be a boiler, a turbine, an electric generator, both individually and in a certain combination.

Generating unit

can be in operable state, fail, go into inoperable state, be repaired and go back into operable state. Failure here refers to any damage in the unit that requires its disconnection from the system. Generating units are characterized by a large proportion of gradual failures. The gradual effect is that often occurring damages do not require immediate removal of the load from it and disconnection from the system, but allow you to postpone this until a more favorable moment for the system (for example, until the total load of the system is reduced or during the start-up of the backup unit). In addition, the units can be quickly disconnected for scheduled repairs on them or put into reserve. Thus, generating units must be modeled by elements that can be in three states: operable and two inoperable (emergency and repair).

From the reliability point of view, it is also important that the property of the unit, such as the time of starting and switching it into operation and the speed of load set, is also important.

The main reliability indicators are: the frequency of all failures, including sudden, gradual; frequency of scheduled shutdowns for repair, including capital, in the current one; average duration of emergency repair; average duration of scheduled repairs, including capital repairs; current; relative duration of the unit in emergency repair.

Generalized load

is a collection of all system consumers that can be selectively disconnected by the control system. First of all, the control system here refers to a set of dispatching instructions on disconnection in case of the need of certain consumers, automatic frequency unloading (AFR) and frequency automatic repeated switching on (VHPV) of consumers.

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