Destabilizing factors and threats to reliability.

The analysis of PS reliability is based on the interaction model of the following components:
- objects of vulnerability;
- destabilizing factors and threats to reliability;
- methods to prevent threats to reliability;
- methods to improve reliability.
Objects of vulnerability that affect the reliability of the PS are:
- computing process;
- object code of programs;
- database information;
- information issued to consumers.
These objects are affected by various destabilizing factors, which are divided into internal and external.
Internal sources of threats to the reliability of complex PS operations are inherent in the objects of vulnerability themselves:
- design errors in the formulation of the problem;
- algorithmic development errors in the specification of the functions of the PS, in determining the structure and interaction of the components of the program complexes, as well as when using the database information.
- programming errors in the program texts and documentation errors on the software.
- insufficient quality of protective equipment.
External destabilizing factors are due to the environment in which the objects of vulnerability operate. They are:
- personnel errors during operation;
- distortion of information in communication channels;
- failures and equipment failures;
- reconfiguration of information system equipment.
To completely eliminate all these factors is impossible. Therefore, it is necessary to develop tools and methods to reduce their impact on the reliability of PS. The degree of influence of all internal destabilizing factors and some external factors on PS reliability is determined to the greatest degree by the quality of PS design, development, maintenance and documentation technologies.
Methods to prevent threats to reliability:
- prevention of design errors;
- systematic testing;
- mandatory certification.
Methods to improve reliability:
- temporary redundancy;
- information redundancy;
- software redundancy.

Consequences of reliability violations:
- the destruction of the computational process;
- destruction of database information;
- destruction of the program text;
- destruction of information for consumers.
Methods of providing NGOs: in modern automatic software creation technologies, there are methods that allow:
- create software modules and high-quality functional components;
- prevent design defects due to efficient technologies;
- detect and eliminate various errors and defects in the design, development and maintenance of the program by testing systems at all stages of the life cycle of the PS.
- certify the achieved quality and reliability of PS in the process of testing and certification;
- promptly identify the effects of program and data defects and restore reliable program performance.
The integrated application of these methods can significantly reduce the impact of threats. Those. the level of achieved reliability depends on the resources allocated for its achievement, and on the quality of the technology used at all stages of the life cycle of the substation.
The prevention of mistakes and improvement of technical and economic indicators of PS is provided by the use of modern technologies and CAD systems, which are combined with the concept of CASE-technology and languages ​​of the IV generation.
CASE-technologies are high-performance, resource-saving technologies for creating program complexes. They can significantly reduce the level of system, algorithmic and software errors.
To detect and eliminate design errors, all stages of the development and maintenance of the PS d. supported by methods and tools of automated system testing.
Testing is the main method of measuring quality, determining the correctness and real reliability of programs at all stages of development. Test results should be compared with the requirements of technical specifications or specifications.
In addition to the above methods of preventing threats to reliability, there are operational methods to increase reliability: temporary, informational, and software redundancy.