Training electric bench for monitoring and assessing insulation condition of ship's electrical power system

Abstract

FIELD: control and measuring equipment.SUBSTANCE: invention can be used for practical reinforcement of educational issues on monitoring and assessing the state of insulation of a ship's electrical power system (EPS), as well as for research purposes in the specified area. The training electrified bench for monitoring and assessing the insulation condition of the ship's electric power system includes an equivalent electrical equivalent circuit of the ship's electric power system, a measuring current transducer and an analogue-to-digital converter (ADC), a measuring transducer of the equivalent insulation resistance of the ship's electric power system (Rmeas), wherein the equivalent electrical equivalent circuit is electrically supplemented by a transformer (Tr), the primary winding of the transformer is connected to a three-phase current source, the secondary winding, representing an equivalent generator, supplies power to receivers Z1... Zn through switches B1... Bn, wherein Zn consists of two series-connected elements for placing connection points of the external circuit between them, the receivers are electrically connected to the ship's hull through insulation resistances r1... rn, and the leakage circuit comprises variable resistors Ry simulating current leakages of different levels through the insulation of the receivers, which are connected to the beginning of the phases of the receivers, or to the middle of the phases of the receivers, or to the end of the phases of the receivers.EFFECT: physical modelling of normal and emergency states of the insulation of the electrical power system on the diagram of the electrified bench.1 cl, 1 dwg

Description

[0001] The invention relates to control and measuring equipment and can be used for practical reinforcement of educational issues on monitoring and assessing the state of insulation of a ship's electrical power system (ESS), as well as for research purposes in the specified area.

[0002] Background of the invention. The theoretical study of these issues is carried out using an equivalent electrical circuit of a power system (PSS), which is electrically connected to the ship's hull via equivalent insulation resistances. For practical application of this topic, it is necessary to implement this circuit in a training electrical setup that allows for physical modeling of all possible insulation conditions of the PSS. Such modeling is unacceptable for a real PSS due to the risk of creating emergency situations.

[0003] According to the concept of the proposed invention, conditions are created in the electrical circuit of the ESS stand that influence the change in the value of its insulation resistance, and the causes of this change are judged using the corresponding features.

[0004] The invention [1] is known - “A method for determining the power released in current leaks to the housing, at the site of damage to the insulation of the phases of an electrical network with an isolated neutral.”

[0005] According to this method, in order to determine the specified power, various insulation states of the EPS are simulated on a computer equivalent electrical circuit of the EPS.

[0006] The application of the method [1] for the claimed invention is limited by the impossibility of physically modeling the states of the insulation of the ESS.

[0007] The invention [2] is known - “A method for determining an emergency decrease in the insulation resistance of a ship’s electrical network and determining the resistance of a faulty section of insulation.”

[0008] The implementation of the specified method makes it possible to judge the decrease in the insulation resistance of the ship's electrical network associated with the formation of a faulty section of insulation, and to determine the value of its resistance.

[0009] The application of the method [2] for the claimed invention does not allow for the performance of physical modeling of all possible states of ESS insulation for educational and research purposes.

[0010] The closest to the proposed invention in its technical essence is the "Method for determining the location of a decrease in insulation resistance" [3]. In this invention, a physical equivalent electrical circuit of the winding of a ship's demagnetization device with electrical connections of the winding circuit to the ship's hull through insulation resistance is used for the physical modeling of current leakage through the insulation of the winding to the ship's hull and, based on a set of readings from measuring instruments, as well as by performing appropriate calculations, an assessment is made of the circuit location of the current leakage to the hull.

[0011] The significant differences between the proposed electrified test rig and the device in [3] are substantiated by the fact that the said test rig implements a three-phase equivalent electrical circuit of the ESS, containing an equivalent ESS generator, a load circuit with electrical receivers, as well as electrical circuits connecting the load circuit to the vessel's hull via its insulation resistance and a leakage circuit simulating current leakage through the insulation. This circuit enables physical modeling of all possible normal and emergency states of the ESS insulation.

[0012] The technical result of the proposed invention is the physical modeling of normal and emergency states of the insulation of the electrical power system on the diagram of the electrified stand.

[0013] The specified technical result is achieved due to the fact that the equivalent electrical circuit of the ESS, implemented in the electrified stand, contains a load circuit with electrical power receivers, as well as electrical connection circuits of the load circuit with the ship's hull through its insulation resistance and a leakage circuit simulating current leaks through the insulation.

[0014] Figure 1 shows a diagram of a training electrified stand for monitoring and assessing the insulation condition of a ship’s electrical power system with the conventional symbols used in it:

[0015] Tr - a transformer that electrically separates the primary and secondary windings. The primary winding of the Tr is connected to a three-phase current source, and the secondary winding, representing an equivalent generator (ESS), is connected via switches B1,……, B i ,……, B n supplies power to receivers Z1,……, Z i ,……, Z n (Z nconsists of two series-connected elements to accommodate the connection points of the external circuit between them). The specified receivers through the insulation resistances r1,……, r i ,……, r n electrically connected to the ship's hull - K. The leakage circuit contains variable resistors R y , simulating current leakage of various levels through the receiver insulation, which can be connected to the beginning of the receiver phases - to points 1, 2, 3, or to the middle of the receiver phases - to points 4, 5, 6, or to the end of the receiver phases - to point 7. The measuring converters of the phase current i supply a signal proportional to the phase current to the analog-to-digital converter ADC. The measuring converter of the equivalent insulation resistance ESS R из- Ω supplies a signal proportional to the measured value to the ADC. The phase-to-ground voltage measuring transducers (V) supply a signal proportional to the measured value to the ADC. The digitized signals from the ADC are fed to a computer, which records these signals as a function of time, processes them, and displays the results.

[0016] The operating principle of the electric stand.

[0017] Determination of normal insulation resistance levels of ESS.

[0018] Normal insulation resistance levels of ESS are determined

[0019] normal values ​​of insulation resistance of receivers r1,……, r i, ……, r n , as well as the number of receivers connected to the load [4, p.50] by means of switches B1……, B i, ……, B n Minimum normal insulation resistance level of ESS - R из1will occur when the operating mode of the power supply system requires all power supply system receivers to be connected under load. The average normal insulation resistance level of the power supply system is R из2 will occur when the operating mode of the power supply system requires connecting half of the power supply system receivers under load. The maximum normal insulation resistance level of the power supply system is R из3 This occurs when the operating mode of the power system requires one-third of the power system's receivers to be connected under load. There is an inverse relationship between the power system's load current, determined by the number of receivers connected under load, and the normal insulation resistance levels of the power system, which is a statistical relationship in a real power system.

[0020] To determine the normal insulation resistance levels of the ESS, the relationship is found between the phase current i of the ESS, determined by the number of receivers connected under load, and the equivalent insulation resistance of the ESS - R из . Normal insulation resistance levels of the ESS are recorded - Rиз1 , R из2 , R из3 , corresponding to typical operating modes of the ESS.

[0021] Modeling emergency states of electrical power system insulation.

[0022] The initial standard operating mode of the ESS is determined by the number of receivers connected to the load.

[0023] To simulate emergency conditions of the ESS insulation, the leakage circuit is connected to a receiver with leakage connection points. To simulate a decrease in R из At the beginning of the receiver phases, the leakage circuit is connected to points 1, 2, 3. To simulate a decrease in R из in the middle of the receiver phases, the leakage circuit is connected to points 4, 5, 6. To simulate a decrease in R из At the end of the receiver phases, the leakage circuit is connected to point 7. Leakage levels are set using variable resistors R y .

[0024] Signals from measuring converters of phase current i of the ESS, equivalent insulation resistance of the ESS R из- Ω, voltages between phases and the housing V as a function of time, as well as normal insulation resistance levels R из1 , R из2 , R из3 for typical operating modes of the ESS, they are used in the computer by the algorithm for assessing the state of insulation as signs that characterize, in their totality, typical causes of a decrease in the insulation resistance of the ESS: emergency decrease in R из below normal level due to wetting (flooding) of the ESS element; emergency reduction of R из below normal level due to connection to the load of a receiver with reduced insulation resistance; single-phase arc (metallic) short circuit to the housing at the beginning of the phase(s) or in the middle of the phase(s), or at the end of the phases; intermittent arc (metallic) short circuits of the phases to the housing, and others.

[0025] Sources of information

[0026] 1. https: / / findpatent.ru / patent / 256 / 2560034.html.

[0027] 2. Patent for invention No. 2681265.

[0028] 3. Patent for invention No. 2739386.

[0029] 4. Ivanov E.A. et al. Safety of electrical installations and automation systems. - St. Petersburg: Elmor, 2003.

Claims

A training electric stand for monitoring and assessing the insulation condition of a ship's electrical power system, including an equivalent electrical circuit of the ship's electrical power system, a measuring current transducer and an analog-to-digital converter (ADC), a measuring transducer of the equivalent insulation resistance of the ship's electrical power system (R из ), characterized in that the equivalent electrical equivalent circuit is electrically supplemented by a transformer (Tr), the primary winding of the transformer is connected to a three-phase current source, the secondary winding, representing an equivalent generator, through switches B1... B n provides power to receivers Z1… Z n , while Z n consists of two series-connected elements to accommodate the connection points of the external circuit between them, receivers through insulation resistances r1… r nelectrically connected to the ship's hull, and the leakage circuit contains variable resistors R y , simulating current leakages of various levels through the insulation of receivers, which are connected to the beginning of the receiver phases, or to the middle of the receiver phases, or to the end of the receiver phases.

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