Filter compensating device for three-phase power system
(57) Abstract:Usage: to reduce electricity losses by introducing into the design of the transformer. The inventive filter compensating device has three transformers, three winding of each phase which are located on the same rod, the first same conclusions first and second windings connected to the mains power supply system, the first conclusions of the third windings connected in a star schema, the second the conclusions of the first winding connected to the capacitor Bank, main conclusions of the second winding is connected to the reactor, the second the third winding is connected to the resistor, the ratio of the number of turns of the second winding W2the number of turns of the first winding W1choose from the equation , where is the angular frequency of the supply network; C is the capacity of the phase capacitor Bank; L is the inductance of the phase of the reactor. 1 Il. The invention relates to electrical engineering, namely for industrial power generation.Reduce losses and improve power quality in power supply systems of industrial plants is achieved by reactive power compensation and filtering harmonics.It is known that DL is the harmonic content of the mains voltage, especially in respect of high-order harmonics, since capacitive reactance is inversely proportional to the frequency 
However, in connection with the specified filtering properties of the capacitor battery, the low order harmonics are not. Meanwhile, for many industrial installations, for example for excavators with AC drives based on direct frequency converters, is required, along with reactive power compensation, filtering a wide range of harmonics.For reactive power compensation and filtering of harmonics of both the low and high order known use of the broadband filter  represents a capacitor battery, serially connected with the parallel reactor and a resistor.However, this filter compensating device (PKU) has a significant drawback: large energy loss in the resistor at the power supply frequency.The aim of the invention is to increase the efficiency of PKU by reducing the power loss in the resistor.The objective is achieved by the fact that in PKU, condenser containing a battery, a reactor and a resistor prompted to enter the three-winding conclusions of the first and second windings are intended for connection to an electrical power supply system, and the first conclusions of the third windings connected in a star schema". Second, the conclusions of the first winding connected to the capacitor Bank, main conclusions of the second winding of the reactor, the second the third winding resistor. The ratio of turns of the first and second windings of the transformer is chosen from the equality
CL (0,95-1,05) where the angular frequency of the supply network;
With the capacity of the phase capacitor Bank;
L the inductance of the phase reactor;
W2the number of turns of the second winding;
W1the number of turns of the first winding.The necessity and sufficiency of the specified confirmed by the following.In the prototype resistor, where the main energy losses in the circuit, directly connected with the mains supply. In the inventive PKU between the network and the resistor (as between the network and the reactor network and the capacitor Bank) is incorporated winding of the transformer. The parameters of the elements are selected (in accordance with the formula) that the resistor excluded the loss at the frequency of the mains supply. This is due to the fact that the magnetomotive force of the winding connected to the inductance, and winding connected to the capacitor Bank, is balanced at a frequency of bicause the er in it.Specified is displayed in the physico-mathematical circuit analysis PKU.The coefficient in the formula takes into account the design requirements to the elements, the parameters of which are calculated according to the formula. The range of values of the coefficient is determined based on the preservation conditions of practical balance magnetomotive forces of the first and second windings, i.e., conditions to ensure the cost effectiveness of the decision.Costs caused by the introduction in PKU transformer, significantly less funds obtained by reducing energy losses, which is confirmed by the calculations.The drawing shows a schematic diagram of the inventive PKU.PKU contains capacitor battery 1, the reactor 2, the resistor 3.The transformer has 4 windings 5, 6, 7, each of which is located on three cores of the magnetic circuit 8. The beginning (or end) 9 winding 5 and the beginning (or end) 10 winding 6 are intended for connection to the mains supply 11. In this case, the findings 9 and 10 are connected together inside the transformer, forming a three pin 12 located outside the transformer and connected to the mains supply 11. In other cases, depending on konkretnyh ends of the windings. The latter findings 13 winding 5 is connected with the capacitor Bank 1, the second conclusions 14 winding 6 with the reactor 2. Some conclusions 15 winding 7 is connected in a star schema, other findings 16 is connected to the resistor 3.The calculation of orbits let us consider a specific example of PKU for power system dragline ESH-25.90 actuators pressure, lift, turn on "direct frequency Converter induction motor". Angular frequency 314 is set.Using a mathematical model of the power system, defined values=99 µf and L=mH 613.Ratio 2CL 5,983
Based on the optimization calculations of the transformer, select the optimal diameter of the magnetic circuit, which, at a given induction uniquely identifies the number of turns of one of the windings, for example the first:
W1=51. Then W2=5,h=305,13.Because structurally, the number of turns must be a value, accept W2=305.5,98
In this case, the coefficient before relation W2/W1equal to one.Thus, the equality relationship W2/W1work 2CL is sustained. In this case, the magnetomotive force of the windings 5 and 6 osnovnom the absence of losses in the resistor unlike the prototype, where they take place.Higher harmonics of the mains causes the currents in the capacitor battery 1, the reactor 2 and the resistor 3. Since the inductive impedance of the reactor is proportional to the frequency, the higher harmonic current is significantly suppressed in the reactor.In the resistor the energy of the higher harmonics is dissipated, as in the prototype. However, the total loss at the fundamental frequency and higher harmonics in the inventive device is much less than in the prototype. Filter compensating DEVICE FOR three-PHASE POWER SYSTEM, condenser containing a battery, a reactor and a resistor, characterized in that it additionally introduced three three-winding transformer, the windings of each phase which are located on the same rod, with the first same conclusions first and second windings are used for connection of the mains power supply system, the first conclusions of the third windings connected in a star schema, the second the conclusions of the first winding connected to the capacitor Bank, main conclusions of the second winding of the reactor, the second the third winding with a resistor, the ratio of the number of vidoy second winding W2the number of turns of the first winding W1area;
L the inductance of the phase of the reactor.
FIELD: electrical engineering.
SUBSTANCE: two engineering solutions are proposed which are characterized in common engineering goal and common approach to solution. Power supply has transformer incorporating primary windings 1, magnetic core 2, and secondary windings 3; connected in series with the latter is diode bridge 4 closed through poles to reactor coils 5 and 6. Novelty is that central lead of reactor coils 5 and 6 is connected to neutral of load 7. The latter is connected to supply mains through switch 8. Diode bridge with similar double-coil reactor is inserted in series with neutral of all three phases of three-phase load. Novelty in this alternative is that reactor center tap is connected to neutral of supply mains. Damping (smoothing down current peaks) is effected both when three-phase and single-phase loads are connected.
EFFECT: enlarged functional capabilities, ability of damping inrush load currents.
2 cl, 2 dwg
FIELD: computer-aided checkup of electrical energy characteristics.
SUBSTANCE: proposed method involves evaluation of coefficients of current and voltage sinusoid distortions, checkup of these characteristics for compliance with their rated values, and generation of control signal by devices correcting sinusoid of voltage and current levels. This method is characterized in that subharmonic and higher fractional components of current and voltage are included in evaluation of coefficient of current and voltage sinusoid distortions due to determination of actual period of voltage and current variations with time.
EFFECT: enhanced precision of checking voltage and current for their sinusoid distortions.
1 cl, 4 dwg
FIELD: railway transport.
SUBSTANCE: invention relates to longitudinal supply wire systems of non-traction consumers arranged near ac electrified railways. Proposed high-voltage wire system contains three-phase traction transformer connected with contact system and rail-earth and longitudinal power supply line connected with power consumer through electrical meter and consisting of two wires-phases under electromagnetic influence of contact system. Said line is additionally provided with third wire-phase grounded at substation and three-contact switch designed for simultaneously switching off three wires-phases at system supply cutoff mode. All three wires-phase are arranged on supports of contact system or on separately standing supports from field at equal distance from contact system. Electrical meter is made in form of three-element energy meter one element of which is connected to grounded wire-phase in direction of consumer. Use of proposed system reduces asymmetry of voltages at consumers and provides possibility of use of three-element energy meters and precludes emergency situations owing to no resonance conditions with no power losses for resonance.
EFFECT: increased economy of system.
FIELD: electrical engineering.
SUBSTANCE: proposed method intended to enhance power quality characteristics for users subject to negative influence of higher harmonic components includes generation of circuit current higher harmonic components which are in phase opposition to higher harmonics of supply mains using electrical energy of independent power supply.
EFFECT: enhanced electrical energy quality characteristics for power consumers.
1 cl, 3 dwg
FIELD: electrical engineering.
SUBSTANCE: proposed method used to enhance quality characteristics of electrical energy supplied to users susceptible to impact of negative factors of electrical-energy higher harmonic components includes generation of higher harmonic components of current in network which are acting in phase opposition relative to higher harmonics of supply mains.
EFFECT: enhanced quality characteristics of electrical energy supplied to users.
1 cl, 3 dwg
FIELD: reducing voltage ripples across power consumers incorporating rectifiers and inverters.
SUBSTANCE: proposed device has regulation channel, pulse source, series-connected voltage sensor, AC voltage component computing device, comparison gate, delta-modulator, and four-quadrant converter. Regulation channel has series-connected converter transformer, thyristor bridge, amplifier, and pulse distributor. Converter transformer input is connected to supply mains and pulse source output, to pulse distributor input. Voltage sensor input is connected in parallel with converter transformer primary winding and its output, to input of AC voltage component computing device and to second input of comparison gate; four-quadrant converter output is coupled with converter transformer secondary winding.
EFFECT: enhanced power output and mean time between failures.
1 cl, 3 dwg
SUBSTANCE: invention is attributed to electric engineering. For this purpose the device contains compensating block, control system, voltage sensing device and current transformer at that the compensating block includes device for alternating voltage component calculating, comparing element, delta modulator and self-commutated voltage inverter. Power unit consists of converter transformer, thyristor bridge and engine. Primary winding of voltage sensing device is connected between network and "ground", secondary winding of voltage sensing device is linked with input of alternating voltage component calculating device and the second input of compensating block comparing element. Primary winding of current transformer is connected between the network and primary winding of converter transformer, secondary winding of current transformer is linked with output of self-commutated voltage inverter of compensating block. Output of control system is connected with the second input of thyristor bridge.
EFFECT: providing maximisation of device operation stability, increase of electric locomotive power and increase of its travelling speed.
FIELD: power production.
SUBSTANCE: when non-sinusoidal shape of supply voltage is decreased, electric power is distributed between electronic devices distorting the shape of supply voltage and electronic devices improving the shape of supply voltage during the semi-wave of supply voltage. Device is connected in parallel with consumers introducing distortions of voltage shape. Main voltage is supplied to the device input. Device includes serial connection of phase-shifting chain, control pulse shaper, dc power supply and power switcher, which connects consumers improving the shape of supply voltage to the mains at a certain period of time.
EFFECT: improvement of supply voltage shape and simplification of device design.
2 cl, 4 dwg
FIELD: physics; radio.
SUBSTANCE: present invention pertains to transformation technology and can be used in power-line filters of radio interference. The technical outcome of the invention is the profound suppression of non-symmetrical electromagnetic interference with simultaneous meeting of electrical safety requirements on limiting capacitive leakage currents. Proposal is given of a method of reducing capacitive leakage currents on power-line radio interference filters, comprising one or more nodes, each of which is connected through a capacitor to the power-line filter lines and the case. The potential of one of the nodes is varied such that, the potential difference at low frequency between the given node and the case approaches zero. Potential of similar nodes of other sections of the filter are simultaneously controlled through chokes, decoupling at high frequency. As a result of reducing the potential difference at low frequency between the node and the case down to zero, all leakage currents on the case are practically eliminated. In particular, to implement the method, a signal is generated, proportional to the voltage between one of the indicated nodes and the case. That signal is applied to the input of a duo-directional amplifier, at the positive supply input of which a more positive voltage is applied through rectification, acting on the lines of the power-line filter at points of connection to capacitors of the given node. At the negative supply input of the duo-directional amplifier, a more negative voltage is applied through rectification from the same points of the lines of the power-line filter. Capacitors are re-charged by the output current of duo-directional amplifier and as a result, voltage between the given node and the case of the filter at low frequency is practically reduced to zero and consequently, all leakage currents on the case are eliminated.
EFFECT: reduced capacitive leakage currents of power-line filters of radio-interference.
2 cl, 3 dwg
SUBSTANCE: invention refers to the sphere of electrical engineering and is of relevance for design and development of technical equipment ensuring improved quality of electric power transmission through three phase four-wire electrical networks and reduction of power losses related thereto due to anharmonicity and asymmetry minimisation. The desired effect is due to the electromagnetic compensator identifying among the phase currents the one whose frequency value is equal to 150 Hz current which current is immediately injected in phase opposition to the third harmonic of the neutral lead current.
EFFECT: compensation for the largest spectral harmonic as circulating within the currents neutral lead.
3 cl, 2 dwg
FIELD: electrical engineering; energy storage, motor starting gear, ac networks.
SUBSTANCE: polarized capacitors or electrochemical batteries are used in standard ac circuits as polarized electrical charge storage devices with new circuit pattern. In one of alternatives opposing-series configuration of first and second polarized devices is used in ac network to improve its operating conditions. At least one dc power supply is provided to keep polarized devices shifted in forward direction when ac signal arrives at them. This ac signal is applied to devices connected in series opposition to excite ac load. These devices are sufficiently shifted by at least one dc voltage supply so that they remain displaced in forward direction upon connection to ac signal.
EFFECT: enhanced effectiveness and economic efficiency of polarized charge storage devices in all their applications.
64 cl, 32 dwg