Title of Invention: Novel Capacitor Bank Design for Three- Phase Reactive Power Networks

Technical Field

[0001] The present invention relates to power generation and distribution systems. More specifically, the present invention provides methods and systems for compensating reactive power.

Background Art

[0002] In recent years, power quality has become a serious problem in power systems with the addition of non-linear loads that draw non-sinusoidal currents and reactive power. Widespread use of power electronics components in electrical devices and industrial applications has become a dominant effect in power quality. Power generation and transmission is a complex procedure, requiring tuning of numerous components in the power system when coupled to amplify the yield. The total power, also referred to as apparent power, being provided by a transmission network, comprises active and reactive components. While active power is transferred into active energy, i.e., heat, light or torque, by the power users, the reactive I inductive power is generally not consumed. Instead, reactive power fluctuates between the source and the load, and is used to build-up the magnetic field required for inductive loads like motors, discharge lamps, transformers, as well as cables and overhead lines.

[0003] As advantageous as it might seem, reactive power does have a number of undesirable consequences. It increases the drawn current for the same load level, which in turn increases the losses, maintenance, and cost of the power system operation. Moreover, it reduces the power stability margin, and under heavy reactive power levels, causes voltage instability.

[0004] For efficient and reliable operation of any power system, controlling the voltage and reactive power is a necessity. This problem is aggravated further by the fact that different types of loads are connected to the system, each with different reactive power requirements. The voltage levels can be stabilized by controlling the reactive power levels at all stages within a system. At the power generation level, active compensation involving the utilization of automatic voltage regulators enables the field excitations to ensure a pre-set voltage level at the output terminals. Within the transmission network, multiple VAR generators can be installed either in series, or, in shunt configuration as compensation alternatives to stabilize the voltage, increase the power flow capacity, release system capacity, and reduce losses.

[0005] Reactive power compensators are mainly defined based on, (i) the technology utilized to achieve the objective, and (ii) the way they are connected (series or shunt) in the transmission system. Traditionally, some of the commonly used methods involved installation of fixed / switched capacitors, synchronous condensers, thyristor-switched capacitors (TSCs), thyristor-controlled reactors (TCRs), and hybrid TSC-TSR methodologies. The above-mentioned techniques do suffer from under / over compensation, requirement of significant protective equipment, and generation of low frequency harmonics.

[0006] Applying capacitors to a system result in a voltage rise from the point of installation back to the voltage source. This occurs because capacitors reduce the amount of current being carried through the system. The voltage rise associated with the installation of a capacitor bank is approximated using the formula:

AV X Q (1)

V “ V ² where, AV is the change in voltage and Q is the capacitor bank size

[0007] As stated, the compensator capacitors found in various industries undergo many difficulties in the face of harmonic voltages. The following equation explains the relationship between voltage and current of the AC capacitor: l=jc2iTfV where, I: current, voltage, C: capacitance, f: frequency

If 380 V of voltage is applied to the 1 st harmonic with the 7th harmonic component, of 30 volts to a capacitor of 100 pF:

V = -T 2 380 sin(2n50t) + -T 2 30 sin(2n350t) 6.6 sin(2n350t) [0008] This aforementioned relation demonstrates that the high-order harmonic components in the applied voltage cause the overcurrent to pass through the capacitor and damage its structure.

[0009] In general, a capacitor has two metallic areas insulated from each other by a so-called dielectric. The capacitance depends on the area of the foils (A), the distance (d) between them and the dielectric coefficient (E) of the insulating material. The capacitance can be mathematically expressed as:

C = £ (A /d) (2)

[0010] The capacitor's tolerated voltage grows with the thickness of the dielectric, and its voltage tolerance increases with the thickness of the metal plates. Further, the film thickness of the capacitors used in typical reactive power compensation systems is 4 pm which does not offer sufficient voltage tolerance. There is a need for new capacitors with higher voltage and current tolerance, even twice that of the existing capacitors. This innovation offers practical, cost-effective ways to address the issue of harmonic pollution, which causes the present capacitors in the electric power industry to lose their responsiveness.

[0011] For reactive power control in distribution and industrial networks, capacitor banks are mainly used in different configurations by changing the connection scheme for switching between a certain number of capacitor sections according to the reactive load requirements. In these applications, mechanically switched capacitor banks are the most economical reactive power compensation resources. Capacitor banks consist of several capacitors per phase, each of which is connected or disconnected, as needed, by mechanical (thyristor) switches. This capacitor arrangement has a control system that monitors the voltage. When the voltage deviates from the desired value by some preset error in either direction, the control switches in (or out) one or more capacitors until the voltage returns inside the defined range, provided that not all capacitors have been switched in or out.

[0012] One of the main disadvantages of using traditionally employed capacitor banks is their reactive power output and its relation to the voltage, making them the least efficient at low voltages. Additionally, continuous compensation requires switching, generating switching surges within the system, causing further complications. Thus, there is a need for redesigning capacitor banks to overcome the performance limitations of the existing systems mentioned earlier.

[0013] In addition, power imbalance is a prevalent issue in the majority of power systems, particularly those used in industry. Triangle-connected capacitive compensators are unable to maintain their full responsiveness under these circumstances.

[0014] Furthermore, in the existing prior arts, a capacitor bank layout linked to a separate and exclusive earth far distant from the grid ground has not been reported, resulting in currents induced by harmonic components and/or power asymmetry not being effectively discharged into the ground and thus not preventing harmonic pollution of the grid. Furthermore, separate neutral wires to each compensator phase are not assigned in the conventional prior art systems.

[0015] Thus, it is desirable to have an improved technique that overcomes the drawbacks of the conventional systems that can mitigate active power losses and harmonic pollution. Also, an improved an improved capacitor structure aimed at increasing the flow and nominal voltage is required to improve the harmonic behavior. The present invention has been made in view of the above circumstances and the central goal of this invention is to prevent damage due to active power losses and harmonic pollution.

[0016] The applicant has devised, tested, and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

[0017] The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.

Summary of Invention

[0018] It is an object of the present invention to address the problems associated with the prior art systems, and a novel and improved technique is provided for overcoming the shortcomings of the prior art systems. This novel reactive power compensator with dynamic star-grounded micro-capacitor configuration can mitigate active power losses and harmonic pollution.

[0019] The present invention recognizes that existing capacitors as well as the connection topologies (star and delta) employed commonly, limit the overall compensation abilities of a power network, especially when faced with asymmetric and harmonic conditions. Additionally, it is understood that although capacitor banks have been utilized for traditional compensator networks, determining the exact capacitances and switching between the available capacitances within the capacitor bank is a tedious process. Further, incorrect capacitances may result in over or under compensation resulting in an inefficient power distribution system.

[0020] It is yet another object of the present invention to provide a star-grounded micro-capacitor-based reactive power compensator that can mitigate active power losses and harmonic pollution.

[0021] It is yet another object of the present invention to provide a unique reactive power compensator with star-grounded capacitor layout, wherein structure of each capacitor has been modified to handle high voltages and currents by increasing the surface area of the capacitor electrodes and the dielectric thickness.

[0022] It is yet another object of the present invention to increase the capacitor's tolerance to excessive voltage and current in order to address the issues with the prior art methods.

[0023] A further goal of the present invention is to provide a micro-capacitor with two aluminum foils separated by 9 pm and housed inside of a metal housing after encapsulation.

[0024] It is yet another object of the invention to devise a reactive power compensator system wherein capacitor suitable for each phase is calculated separately. The proposed reactive power compensator system with the described capacitor structure can optimally operate under normal grid loads, harmonic pollution, and various imbalance scenarios with distinct star-ground connection layouts. [0025] It is yet another object of the present invention to provide a reactive power compensator system with ground-star connection capacitor layout by utilizing uniquely designed capacitor structures.

[0026] It is yet another object of the present invention to provide an improved and efficient reactive power compensator having an improved capacitor structure aimed at increasing the flow and nominal voltage. Additionally, the capacitor bank arrangement has each phase of the capacitors independently linked to the exclusive earth far distant from the grid ground in order to optimize the harmonic behavior. Furthermore, the proposed reactive power compensator is designed to operate autonomously and can adapt to varying load and grid conditions.

[0027] In an embodiment, the present invention proposes a three-phase reactive power compensator network having a plurality of uniquely designed and cost- effective micro-capacitors having higher voltage and current tolerance levels achieved by increasing thickness of dielectric layer as well as electrodes, thereby enabling them to retain responsiveness under harmonic pollution. Further, a three-phase reactive power compensator network comprises a grounded-star connection topology with separate neutral wires apart from the grid neutral, having the advantage of operating under symmetric and asymmetric grid load conditions, and harmonic pollution levels under varying impedance and voltage imbalance scenarios. In addition, a control unit is configured to perform real-time impedance calculations and thereby determining and introducing proportional capacitance values as required for balancing each individual compensator phase.

[0028] According to an embodiment, a reactive power compensator set with an improved capacitor structure aimed at increasing the flow and nominal voltage is provided. Furthermore, to improve the harmonic behavior, the capacitor bank layout consists of a grounded-star topology with each phase of the capacitors separately connected to the exclusive earth well apart from the grid ground. The proposed compensator system is connected to a three-phase line. A measuring unit is connected to each of the three individual phases and is configured to continuously monitor the current, voltage, phase shift, and the harmonics situation on the three-phase line. Further, the measuring unit interfaces to a control unit for continuous monitoring of the network condition and to direct the control unit to compensate manually if required. The measured values are relayed to the control unit, which, depending on the requirement, calculates the capacitance values required for balancing and provides those results to a switching unit. Accordingly, the switching unit swaps the individual capacitors inside each of the three capacitor banks using switches linked to each phase and grounded independently.

[0029] It is yet another object of the present invention to provide three-phase reactive power compensator network having a plurality of uniquely designed and cost- effective micro-capacitors, wherein each of the micro-capacitors comprise two aluminum foil electrodes, wherein two aluminum foil electrodes further include an oxide coated anode and a cathode that are placed at a fixed distance apart from each other. Further, a porous paper spacers are placed between the anode and the cathode before encapsulating them in a metal housing, wherein the metal housing is filled with a suitable electrolyte solution, to aid oxidation, wherein aluminum foil electrodes along with the porous paper spacers are completely submerged, before tightly sealing the entire structure. Also, the surface area of each of the two aluminum foil electrodes and the spacing between the two aluminum foil electrodes is twice of that of commonly employed polypropylene capacitors.

[0030] In one embodiment, this invention presents a star-ground connected microcapacitor-based reactive compensator that can operate under different symmetrical and asymmetrical load and grid conditions. The capacitor design has been modified to ensure adequate power handling at the complexities faced by industrial three-phase capacitor banks. By increasing the surface area of the capacitor electrodes and the dielectric thickness, the capacitor structures have been changed to handle high voltages and currents.

[0031] In another embodiment, each individual phase of the system is compensated by adding capacitors with capacitances proportional to the phase state; in case of no asymmetry, capacitors will have equal capacitances, and unequal capacitances are calculated in case of asymmetric grid conditions. A mathematical procedure for calculating the capacitances is derived by a control unit to determine the compensating capacitor values for each individual phase. As opposed to a conventional star topology with a common grid ground for all phase capacitors, individual grounds for the capacitors connected to each of the three phases resulting in a grounded-star topology has been presented. Harmonics generated as a result of adding compensating capacitors are significantly lower for the grounded-star topology as compared to the conventional star connections.

[0032] In another embodiment of this invention, a control unit has been added with the functionality to actively monitor the grid state (asymmetries, harmonics, etc.), calculate the required compensating capacitance values for each individual phase as deemed necessary, controlling the switching hardware for connecting I dis-connecting the desired capacitances on each phase, and reporting all the network data to a monitoring station. The control unit serves as the brain of the compensator system where, in addition to monitoring and compensating the system, the administrator can override the system settings and manually connect I dis-connect compensating capacitors as the situation demands.

[0033] In the present application, to compensate for a three-phase unbalanced reactive power system, the compensation system has been designed so that in each phase, the capacitive compensators enter the grid in proportion to the phase state. In case of no asymmetry, the capacitors will have identical capacitance. However, under asymmetrical loads or supply voltages, the capacitors in each phase enter the grid with capacitance values proportional to the asymmetry. Entering the network with a proportional capacity means that exact capacitance values need to be known I calculated to make sure the exact capacitor is introduced in the system to compensate. Additionally, the proposed configuration requires separate grounding for capacitors connects on individual phases. By removing the common ground, the harmonic currents generated as a result of introducing compensators in the system are comparatively lower than the conventional configuration.

[0034] These and other objects and advantages of the invention herein and summary will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0035] The foregoing summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the present invention, nor is it intended to be used to limit the scope of the subject matter. Various objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like features. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0036] The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Brief Description of Drawings

[0037] The accompanying figures, which are incorporated herein, form part of the specification and illustrate embodiments of the present invention. Together with the description, the figures further explain the principles of the present invention and enable a person skilled in the relevant art to make and use the invention.

FIG.1

[0038] [FIG.1] shows a cross-sectional view of a cylindrical capacitor.

FIG.2

[0039] [FIG.2] shows a schematic diagram of a cylindrical capacitor.

FIG.3

[0040] [FIG.3] shows a circuit diagram of capacitive three-phase loading in triangle arrangement.

FIG.4

[0041] [FIG.4] shows a circuit diagram of capacitive reactive power compensation with star-ground arrangement.

FIG.5

[0042] [FIG.5] shows AC voltage and current after compensation. FIG.6

[0043] [FIG.6] shows circuit diagrams with corresponding power factor for (a) harmonic behavior of compensators, and (b) extending this limit by reactive power compensation.

FIG.7

[0044] [FIG.7] shows waveforms of three-phase current of compensator capacitors in the presence of harmonics.

FIG.8

[0045] [FIG.8] shows harmonic behavior of compensator, (a) harmonic behavior Vs K0, and (b) harmonic behavior Vs Xc1 /X 1 .

FIG.9

[0046] [FIG.9] shows supply phase voltage waveforms under voltage imbalance conditions, (a) before compensation, and (b) after compensation.

FIG.10

[0047] [FIG.10] shows supply voltage and current for (a) a resistive circuit, (b) an inductive circuit, and (c) a capacitive circuit.

FIG.11

[0048] [FIG.11] shows waveforms of the currents of compensator capacitors under load imbalance.

FIG.12

[0049] [FIG.12] shows a block diagram of the proposed compensator setup connected to a three-phase line.

FIG.13

[0050] [FIG.13] shows the schematic diagram of the proposed compensator network.

FIG.14

[0051] [FIG.14] shows a snapshot of a sample of the proposed compensator bank set.

FIG.15 [0052] [FIG.15] shows a sample panel of the proposed reactive power compensator.

FIG.16

[0053] [FIG.16] depicts an exemplary panel of the proposed reactive power compensator.

Description of Embodiments

[0054] Subject matter will now be described fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific exemplary embodiments and performance metrics. Subject matter may, however, be embodied in a variety of different forms and, therefore, covered or claimed subject matter is intended to be construed as not being limited to any exemplary embodiments set forth herein; exemplary embodiments are provided merely to be illustrative. Likewise, a reasonable broad scope for claimed or covered subject matter is intended. Among other things, for example, the subject matter may be embodied as methods, devices, components, or systems. The following detailed description is, therefore, not intended to be taken in a limiting sense. Further, the embodiments disclosed below are not intended to be exhaustive or to limit the invention to the precise forms in the following detailed description. Thus, it should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present invention.

[0055] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. Likewise, the term “embodiments of the present invention” does not require that all embodiments of the invention include the discussed feature, advantage or mode of operation.

[0056] Various aspects of this disclosure are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It should be understood, however, that certain aspects of this disclosure may be practiced without these specific details, or with other methods, modules, components, elements, materials, etc. In other instances, well-known structures and devices are shown in block diagram form to facilitate describing one or more aspects.

[0057] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of embodiments of the invention. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context indicates otherwise. Various aspects or features will be presented in terms of systems that may include a number of devices, components, modules, sub-modules, and the like. It is to be understood and appreciated that the various systems may include additional devices, components, modules, sub-modules, etc., and/or may not include all of the devices, components, modules, sub-modules, etc. discussed in connection with the figures. A combination of these approaches also can be used.

[0058] In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from the context, the phrase “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, the phrase “X employs A or B” is satisfied by any of the following instances: X employs A; X employs B; or X employs both A and B. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from the context to be directed to a singular form. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including”, when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0059] The following detailed description includes the best currently contemplated mode or modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention will be best defined by the allowed claims of any resulting patent. [0060] As discussed, there is a need for new capacitors with higher voltage and current tolerance, even twice that of the existing capacitors, as evidenced by examinations conducted on the voltage spectrum of various power grids, industries, and power consumers. This innovation offers practical, cost-effective methods to address the issue of harmonic pollution causing capacitors in the electric power industry to lose their responsiveness.

[0061] This application suggests a star-ground linked micro-capacitor-based reactive compensator that may function under various symmetrical and asymmetrical load situations as well as grid settings with modified capacitor topologies. To increase insulation durability and resistance to overvoltage and overcurrent, these modifications entail making the insulators twice as thick. Additionally, suitable capacitive compensators join the grid according to state of each phase; for example, if there is no asymmetry, all capacitors will have equal capacitance. The capacitors of each phase enter the grid with proportionate capacities with asymmetry in the case of load or supply voltage asymmetry.

[0062] With the active power factor and the system in this factor, the required capacitor from the capacitor bank can be calculated and introduced in the network. In order to enter the network with a proportionate capacity, we must determine how much capacitor we require. The necessary capacitor can be determined using a variety of techniques. One of the simplest methods is to use the ka coefficient. The necessary capacitor from the capacitor bank may be computed and added to the network with the active power factor and the system in this factor.

[0063] FIG. 1 and FIG. 2 depicts the cross-sectional views of a typical cylindrical capacitor with the different factors labeled. The two electrodes 11 and 12 are separated by a certain distance d, having a dielectric layer 13 in between the two electrodes, surrounded by a metal wall 14, encased in an aluminum sheath 15, and wrapped inside a protective plastic cover 16.

[0064] This may be done, for example, by doubling the cross-sectional area of the electrode plates and thickening the dielectric layer. The resulting capacitor design, as shown in Table 1 , offers a voltage and current rating that are both 44% and 76% higher, respectively. [0065] In one example, each capacitor includes two aluminum foil electrodes 11 and 12, one of which is an oxide coated anode and the other which is meant to operate as a cathode, and these two electrodes are separated a certain distance apart. Porous paper spacers are also inserted between the anode and cathode before they are encased in a metal container 14. In addition, to help oxidation, the metal housing 14 is filled with an appropriate electrolyte solution, into which the aluminum foil electrodes and porous paper spacers are entirely submerged before firmly closing the entire construction. According to a preferred embodiment of the invention, two electrodes aluminum foil electrodes) are separated by 9 pm and housed inside of a metal housing 14 after encapsulation. Similarly, in one embodiment, the electrode plate cross-sectional area of the proposed capacitor structure is 1 .2 mm, as opposed to 0.75 mm for a typical capacitor. Additionally, according to an embodiment, proposed capacitor architecture comprises electrode plates with a 40 sq m plate area compared to the standard capacitor's 20 sq m plate size.

[0066] According to an embodiment, the structural changes in the capacitors include doubling the insulators' thickness to increase insulation tolerance and resistance to overcurrent and over-voltage. With rising insulator thickness, or in other words, as the film thickness grows, so does the distance between the two capacitor plates (foils). Despite the increased capacitor windings, i.e., greater plate surface, the capacitance stays constant and unchanged. The film thickness of standard 50 F capacitors is 4.5 m. In the suggested system, the film thickness has grown to 9 m.

[0067] Table 1 . Comparison of a common polypropylene capacitor and the proposed capacitor.

[0068] This asymmetrical star-ground connection uses micro-capacitors as capacitors. They prevent the entire set from shutting down if one of the capacitors fails, boosting system dependability.

[0069] The capacitors in each compensator phase will have different values under system imbalance conditions, i.e., unbalanced impedance applied to each unbalanced power factor or voltage supply phase: The capacitance of the phase is calculated as necessary by each phase and placed at the desired position in the phase. Also, the neutral wire of these capacitors is linked to ground.

[0070] Power factor and voltage loss are compensated for in the proposed system. Under load, impedance, and voltage amplitude imbalance circumstances, it outperforms standard triangle or delta connection setups.

[0071] Three-phase capacitive circuits can be connected in one of two configurations; delta (as shown in FIG. 3) and star (as shown in FIG. 4). Although the power transmitted by both the configurations is the same, the selection of any one topology depends on the application; star configuration is mainly employed in transmission systems, while delta topology is utilized in distribution systems. The proposed connection scheme utilizes a star configuration by employing separate ground for each of the phases, preventing the generation of high return currents and mitigating the resulting disruptive phenomenon.

[0072] Based on the actual loading of a network, asymmetry tends to creep into a power transmission and distribution system. In ideal state, the current as well as the voltage in each of the three-phases have the same amplitude and the phase- to-phase difference is fixed at 120 Degrees. Under asymmetric conditions, the amplitude and I or the phase difference may deviate from the ideal causing energy dissipation (as heat) resulting in a damage to the loads. A grounded-star connection can easily respond to any type of asymmetry. The capacitance suitable for each phase is calculated separately and connected in the system as, and when, required. The proposed reactive power compensator system with the described capacitor structure can optimally operate under normal grid loads, harmonic pollution, and various imbalance scenarios with distinct star-ground connection layouts. FIG. 5 shows the voltage 51 and the current 52 in an ideal condition, without the need of compensators, in the absence of any harmonics.

[0073] FIG. 6 shows the voltage stability curves for an inductive circuit 61 and the same circuit 63 with a compensator 64 added to it. A look at the P-V curves for different power factors (PF) of 62 and 65 indicate that a higher voltage solution provides a stable voltage case while the lower voltages indicate unstable voltage operation. Introduction of the compensator clearly depicts stability at higher voltages for a given PF as indicated in 65. FIG. 7 displays the compensator capacitors' three-phase currents in the presence of harmonic components in the sample system. Each current is singly discharged into the earth well. FIG. 8 indicates the proposed compensator's harmonic behavior mounted in the ground post of Tabriz Metal Factory. Although integrating compensators into a system generally increases its harmonic currents, this increase is significantly lower in the proposed compensator system as compared to the conventional grounded- star model.

[0074] For a sample system with balanced phases and unbalanced line amplitudes, FIG. 9 shows the voltage waveforms before compensation 91 and after compensation 92 using the proposed structure. Phase imbalance can be represented as leading or lagging as indicated by the waveforms of FIG. 10. For a three-phase system, under amplitude or phase imbalances, or both, the load imbalance in each phase can be expressed as:

Z1 = R1 + j.X1

Z2 = R2 + j.X2

Z3 = R3 + j«X3 (3) [0075] For a star-connected compensation, the capacitor of each phase is set parallel to that phase load. Thus, the load impedance of each phase in the power grid equals:

ZJ2 =(R_i+ j • (XJ + X_ci))/(-XJ. X_ci + [j . X] J. X_ci ) (4) i = 1 , 2, 3 corresponding to individual phases

[0076] Equating the equation set of 4 to the desired line impedance Z_d yields X_c1 , X_c2 and X_c3, specifying the three suitable capacitance values required to compensate for the line impedance. Appropriately selecting capacitor compensators for each phase aids in balancing the power grid load size and helps modifying its power factor. For a sample system with specifications as defined in Table 2, FIG. 11 shows the currents of capacitors in this mode. As shown, phase compensator capacitors have different currents, due to different capacitances, depending on the requirements of each system phase.

[0077] Table 2. The specifications of a sample system under load imbalance.

[0078] The proposed system is a reactive power compensator set with an improved capacitor structure aimed at increasing the flow and nominal voltage. Furthermore, to improve the harmonic behavior, the capacitor bank layout consists of a grounded-star topology with each phase of the capacitors separately connected to the exclusive earth well apart from the grid ground. FIG. 12 shows the block diagram of the proposed compensator system 122 connected to a three-phase line 121 . A measuring unit 123 connects to each of the three individual phases and continuously monitors the current, voltage, phase and the harmonics situation on the line. According to one embodiment, the measuring unit 123 has one or more voltmeters, ammeters, and power factor meters (e.g., Cos phi meters) capable of measuring the angle between voltage and current of each load phase. The measured values are relayed to the control unit 124, which, depending on the requirement, calculates the capacitance values required for balancing and provides those results to the switching unit 125. According to one embodiment, the switching unit 125 is programmed to connect or disconnect circuit capacitors in response to directions passed by the control unit 124. For example, the switching unit 125 switches the individual capacitors within each of the three capacitor banks 126, through switches 127, connected to each phase and grounded separately through 128. Further, a monitoring station 129 interfaces to the control unit 124 for continuous monitoring of the network condition and to direct the control unit 124 to compensate manually if required.

[0079] According to an exemplary embodiment, a voltage measurement unit 123 measures the voltage of the power system, and a control unit 124 detects the magnitude of the reactive power output from the reactive power output unit based on system voltage and controls the control parameter in the primary mode of operation. The control unit 124 causes an output change period in the second operation mode and changes the magnitude of the reactive power output to the power system by reactive power output unit during the output change period. Based on the voltage change of the system detected at a significant number of detection time points throughout the period of change in output and the value of the corresponding change in reactive power, the control unit 124 calculates the impedance of the power system at various time intervals. The control parameter is in alignment with the estimated system impedance when changes in system impedance are within the acceptable range. The capacitor bank has been presented in the current application with a star-connection topology for imbalanced loads. Because of the capacitor bank's design, the capacitor compensator enters the grid proportionally to the phase load in each phase. [0080] FIG. 13 shows a schematic diagram of the complete installation. The capacitor bank 135 is connected to an overcurrent protection device 133 (e.g., fuse), control unit 132 (e.g., power factor controller), the circuit breaker 131 , and the switch breaker 134 added for additional protection. FIG. 14 shows the capacitor bank unit of the proposed compensator with capacitors 141 connected to contactor 142, a regulator 143, and a current transformer 144. A completely assembled panel based on the invention is shown in FIG. 15.

[0081] In addition, an exemplary panel of the proposed reactive power compensator is shown in FIG. 16, which includes a number of capacitors 161 , contactors 162, overcurrent protection device 163 (e.g., fuse switch), selector key 164, Busbar 165, and a regulator 166.

[0082] As apparent from the foregoing specifications, the invention offers a new and improved configuration of micro-capacitors with higher voltage and current tolerance, even more than twice that of the existing capacitors, as evidenced from tests taken on the voltage spectrum of various power grids, industries, and power users. This innovation offers practical, cost-effective ways to address the issue of harmonic pollution, which causes the present capacitors in the electric power industry to lose their responsiveness.

[0083] Thus, as evident, the novel reactive power compensator having an enhanced capacitor structure that increases flow and nominal voltage is better and efficient as compared to conventional reactive power compensator. In order to enhance harmonic behavior, the capacitor bank layout has each phase of the capacitors individually coupled to the exclusive earth far away from the grid ground. Furthermore, the suggested reactive power compensator can operate autonomously and can respond to changing load and grid circumstances.

[0084] The star connection with the earth well apart from the grid ground, without the overcurrent problem in the earth wire, has the ability to compensate for reactive power while balancing the system in terms of voltage and load impedance. The currents induced by harmonic components and/or asymmetry are practically discharged into the ground. This behavior prevents harmonic pollution of the grid. The proposed system can operate in various load and grid conditions, including symmetrical and asymmetrical operational conditions related to power factor. [0085] The suggested system exhibits a more satisfying performance and responsiveness under unbalanced situations in load power factor impedance and voltage amplitudes, in addition to compensating for power factor and voltage drop.

[0086] The present invention proposes a ground-star connection of compensator capacitors with distinct neutral wires to each compensator phase and connecting neutral wires to the earth considerably distant from the grid. This innovation offers practical, cost-effective methods to address the issue of harmonic pollution causing capacitors in the electric power industry to lose their responsiveness.

[0087] To improve the tolerated voltage of capacitors, their structure is changed to justify the star connection above the triangle connection. The capacitive compensators enter the grid in accordance to the condition of each phase. If there is no asymmetry, the capacitors will have the same capacitance. When asymmetrical loads or supply voltages are present, the capacitors in each phase enter the grid with capacitance values proportionate to the asymmetry. The suggested system not only adjusts for power factor and voltage drop, but it also performs and responds more satisfactorily under unbalanced situations in load power factor impedance and voltage amplitudes. This compensator has several advantages, including decreased capacitor sensitivity to overvoltage, lower beginning current, and lower total system costs.

[0088] In the proposed invention, the dielectric thickness has been raised in the structure to enhance voltage and current tolerance. Also, the star-ground pattern is adopted for the capacitor bank layout. Additionally, the capacitive compensators enter the grid in proportion to the phase state in each phase. Furthermore, the capacitor bank arrangement is linked to the earth well in each phase separately from the grid ground.

[0089] Finally, the proposed system may be used in an infinite number of applications, including electricity transmission and distribution grids, small and big enterprises and industries, agricultural, commercial, and administrative sectors.

[0090] While the disclosed embodiments of the subject matter described herein have been shown in the drawing and fully described above with particularity and detail in connection with several exemplary embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without materially departing from the novel teachings, the principles and concepts set forth herein, and advantages of the subject matter recited in the appended claims. Hence, the proper scope of the disclosed innovations should be determined only by the broadest interpretation of the appended claims so as to encompass all such modifications, changes, and omissions. In addition, the order or sequence of any process or method steps may be varied or resequenced according to alternative embodiments.