Abstract:
A system of surge suppressor units is connected at multiple locations on a power transmission and distribution grid to provide grid level protection against various disturbances before such disturbances can reach or affect facility level equipment. The surge suppressor units effectively prevent major voltage and current spikes from impacting the grid. In addition, the surge suppressor units include various integration features which provide diagnostic and remote reporting capabilities required by most utility operations. As such, the surge suppressor units protect grid level components from major events such as natural geomagnetic disturbances (solar flares), extreme electrical events (lightning) and human-generated events (EMPs) and cascading failures on the power grid.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. patent application Ser. No. 15/266,535, filed on Sep. 15, 2016, which is a continuation of U.S. patent application Ser. No. 14/931,060, filed on Nov. 3, 2015 (now U.S. Pat. No. 9,450,410), which is a continuation of International Application No. PCT/US2015/035305, filed on Jun. 11, 2015, which claims benefit of U.S. Provisional Patent Application No. 62/010,746, filed on Jun. 11, 2014, the disclosures of all of which are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a surge suppression system for medium and high voltage systems of a power grid. 
       BACKGROUND AND SUMMARY 
       [0003]    Current surge suppression systems have been developed to protect equipment from voltage transients on one side of a three-phase power supply bus used in industrial settings such as in plants, factories, or other large scale systems. In one known voltage surge suppressor, three single-phase transformers are provided with terminals that are each connected through a fused disconnect to a respective single-phase power supply on the power-supply bus. This surge suppressor protects against voltage transients, which can severely damage or destroy equipment connected to the effected three phase circuit or can cause power outages throughout the plant. The surge suppressor circuit operates as a surge and fault protector for any equipment on the power bus. This surge suppressor system is usable with 480 volt distribution systems powered by a  2000  to  3000  kVA ungrounded delta power transformer that feeds approximately 1000 ft of bus duct, so as to generally have about 1 to 3 Amperes of charge current. This charge current may generally be just over 2 Amperes by actual amperage determined by readings in the field, wherein the variations are due to the lengths of the feeder cable and bus duct as well as the number and size of the electric motors and power factor correction capacitors operating at any given time. More typically, resistance grounding circuits constantly bleed this charge to ground to help prevent grounding problems. The known surge suppressor is connected to the bus bars and does not bleed this energy to ground, but uses this charge energy to help stabilize and balance the phase voltages to ground. 
         [0004]    This known surge suppressor is installed in and protects equipment connected to a power supply bus at the facility level. However, there is a need for a surge suppressor system for medium and high voltage electrical systems on the grid located outside of and remote from an industrial bus bar power supply system. 
         [0005]    A power grid is comprised of many components that are generically described as generators, transformers, transmission and distribution wires and controls. Generators are driven by many forms of energy such as coal, natural gas, nuclear fission, hydro, solar and even wind to name a few. Once power is created at a relatively low voltage around 6,000 volts it is stepped up to high voltage (often in the hundreds of thousands) using large power transformers (LPTs) which allow the electricity to be more effectively delivered over miles of high tension (transmission) wires. Once the electricity reaches the general area where it will be used it is then stepped back down closer to the final voltage at sub/distribution stations. Distribution lines carry near-low voltage electricity on roadside power poles or underground to the final transformer before being delivered into buildings for use. 
         [0006]    The present invention is a surge suppressor system that improves upon existing phase adder circuit products, is designed to provide grid-level protection to residences and industrial facilities prior to delivery of the power to these structures so they can withstand higher voltages, provide monitoring and communication from remote settings, and provide more robust installation platforms, and configures the system of surge protection devices in parallel to protect grid level applications on both sides of a power system where the need exists to step power either up or down. 
         [0007]    On a medium or high voltage system, the current invention would be configured to handle large and rapid energy “drain offs”, prevent interference from high voltage/high magnetic flux, allow remote performance maintenance, and increase protection, as required, from physical attacks and severe over voltages. When the invention is installed in parallel with critical grid infrastructure, the components of the grid are protected against: 
         [0008]    Transients: An impulsive transient is what most people are referring to when they say they have experienced a surge or a spike. Many different terms, such as bump, glitch, power surge, and spike have been used to describe impulsive transients. Causes of impulsive transients include lightning, poor grounding, the switching of inductive loads, utility fault clearing, and Electrostatic Discharge (ESD). The results can range from the loss (or corruption) of data to physical damage of equipment. Of these causes, lightning is probably the most damaging. The surge suppressor devices of the current invention provide grid-level protection against such transients. 
         [0009]    Interruptions: An interruption is defined as the complete loss of supply voltage or load current. The causes of interruptions can vary but are usually the result of some type of electrical supply grid damage, such as lightning strikes, animals, trees, vehicle accidents, destructive weather (high winds, heavy snow or ice on lines, etc.), equipment failure, or a basic circuit breaker tripping. While the utility infrastructure is designed to automatically compensate for many of these problems, it is not infallible. 
         [0010]    Sag/Under-voltage: A sag is a reduction of AC voltage at a given frequency for the duration of 0.5 cycles to 1 minute&#39;s time. Sags are usually caused by system faults and are also often the result of switching on loads with heavy startup currents. 
         [0011]    Swell/Over-voltage: A swell is the reverse form of a sag, having an increase in AC voltage for a duration of 0.5 cycles to 1 minute&#39;s time. For swells, high-impedance neutral connections, sudden (especially large) load reductions, and a single-phase fault on a three-phase system are common sources. 
         [0012]    Frequency Variations: There are all kinds of frequency issues from offsets, notching, harmonics, and inter-harmonics; but these are all conditions that occur largely in the end user&#39;s power system. These variations happen because harmonics from loads are more likely in smaller wye type systems. The high frequency variations that may lead to massive interconnected grid failure would come from the sun or enemy attack. Damage to only a few key infrastructure components could result in prolonged blackouts and collateral damage to adjoining devices. Solar flares are natural occurrences that vary in severity and direction. This “solar weather” is sent out from the surface of the sun throughout our solar system in all directions. These flares contain large amounts of magnetic energy and depending on how they hit the earth can cause component damage on the surface or by temporarily changing the properties of the planet&#39;s magnetic core. Either way, a direct hit of large proportion could cause equipment failure and black out entire regions. Electromagnetic Pulses (EMP) can be used in similar fashion but directed by enemy combatants in the form of a high altitude nuclear explosion. A well-executed detonation over Cincinnati, Ohio could black out 70% of the American population. Damage to large power transformers or generators could take months to repair. The high frequency disturbance of nuclear explosions can destroy unprotected components much like an opera singer&#39;s voice can break a glass. The magnitude of each disturbance may depend on the source but each can be mitigated effectively through the use of a phased voltage stabilization system such as the invention. 
         [0013]    Current surge suppression technology may attempt to address these disturbances on the facility side of the power distribution system, so as to directly protect equipment in a facility, and also at a grid level but these technologies possess drawbacks in protecting against these disturbances. 
         [0014]    As one example of a known surge suppression technology, capacitors are thin conductors separated by even thinner layers of insulation. Capacitors have a design rating for current and voltage. If this rating is not exceeded they will typically operate for 10 to 15 years. One high voltage spike may (and generally will) cause catastrophic failure of capacitors. In factories with 4,000 power factor correction capacitors, it is not uncommon to have 300 to 500 capacitors fail each year due to high harmonic current or high voltage spikes. 
         [0015]    In another example, SPD (Surge Protective Devices) are solid state devices constructed in various sizes. Like capacitors, their ratings are also in current and voltage. When the MOV (Metal Oxide Varistor) is hit with many low-level voltage spikes it degrades, and the “clamping voltage” will rise as the MOV breaks down, allowing the clamping voltage to continue to rise until it no longer protects the equipment it was installed to protect. When a voltage spike hits the MOV above the rated voltage, it starts to conduct thousands of amps to ground, causing noise on the ground system and very high heat within the SPD. If the event is longer than a few millionths of a second, the MOV could be destroyed, and therefore would no longer protect the equipment it was installed to protect. 
         [0016]    Further, Faraday cages have been used for many years to house and protect computer hardware and sensitive data in factories, as well as some government and military buildings. They recently have been touted as a solution to solar flares, lightning and EMP pulse issues. However, most buildings are not built within a metal enclosure and it is difficult and expensive to properly design and build these enclosures. Most automobiles, trucks, trains and planes are totally enclosed by metal, but they offer no protection from any of these events. By design, the metal enclosure must have a suitable solid ground connection as it relies heavily on enclosing and shielding the sensitive electrical equipment and removing the energy by draining it to ground. The power company uses the Faraday cage design in some of their grid tie substations. They are extremely large and expensive. 
         [0017]    The greatest threat to the grid/LPTs is the presence of an electromagnetic pulse (EMP) or geomagnetic disturbance (GMD), the latter would originate as a solar flare and the prior would be from enemy weaponry. Either threat could cause an overworked LPT to be saturated with power and cause the transformer to burn out. With an EMP, saturation could happen in less than a second so detection systems are worthless. 
         [0018]    GMD is slower to cause damage so detection systems could reduce the load on a transformer which could allow it to ride out the GMD incident. This brown out or temporarily blacked out condition could last minutes, hours or days depending on the severity of the solar storm. In the case of the 1869 Carrington Event the Earth was pummeled with solar magnetic energy for nearly a month. While the grid could survive such an event if properly managed it would hardly be well received by citizenry to be without power that long. 
         [0019]    Simply, Large Power Transformers cannot be protected with old technology like Faraday Cages. The hundreds of miles of wire that connect the LPT to sub stations way down the line act like antennae and harvest EMP with such efficiency that the Faradays would have no value. Surge protecting devices are not fast enough to arrest an EMP which occurs in a millionth of a second or handle the massive electron flow that occurs at the transmission level without allowing current bleed through to the LPT which would ultimately have the same effect as an unprotected system. Grounding systems would try to route surplus current from an EMP to earthen ground probes or mats but that excess energy would likely find its way back into the power system through the ground bus and result in burnout as well. 
         [0020]    The present invention relates to a system of surge suppressor units connected at multiple locations on the grid to provide grid level protection against various disturbances before such disturbances can reach or affect facility level equipment. The effect of the invention is significant for protecting grid level applications. With the unique application and design of the present application, the surge suppressor units of the present invention would effectively prevent major voltage and current spikes from impacting the grid. In addition, the surge suppressor units included various integration features which provide diagnostic and remote reporting capabilities required by most utility operations. As such, the surge suppressor units protect the grid level components from major events such as natural geomagnetic disturbances (solar flares), extreme electrical events (lightning) and human-generated events (EMPs) and cascading failures on the power grid. The invention also provides significant protection against arc flashes and reduces voltage harmonics that exists in “normal” grid operations. 
         [0021]    The reporting features of the inventive surge suppressor unit are also unique to protecting medium and high voltage systems that are often in remote or isolated settings. Unlike devices designed to protect local low voltage equipment and infrastructure, real time diagnostic reporting from the surge suppressor unit is critical to ensure it is working effectively and providing the continuous protection needed to protect power systems like the US power grid. 
         [0022]    As discussed, various known technologies (such as MOVs, Faraday cages, even similar devices designed with fused disconnects) attempt to also correct voltage imbalances. These devices either do not provide the scalability to the voltage requirements at the grid level or “burn out” when significant voltage is applied. These technologies also do not provide reporting, remote diagnostics, or protection from ancillary dangers such as arc flashes or localized voltage overflow. The surge suppressor system of the present invention provides each of these benefits and is also completely scalable for various grid level applications. 
         [0023]    Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1A  is a diagrammatic view of power grid interfaces with a system of surge suppressor units connected thereto at various locations on the electrical supply grid. 
           [0025]      FIG. 1B  is an enlarged partial view of  FIG. 1A  showing the transmission grid. 
           [0026]      FIG. 1C  is an enlarged partial view of  FIG. 1A  showing the distribution grid. 
           [0027]      FIG. 2  illustrates typical fault conditions. 
           [0028]      FIG. 3  diagrammatically illustrates a protection scenario ( 20 ) for grid level components (e.g. substations) at a grid level. 
           [0029]      FIG. 4  illustrates a surge suppression unit ( 30 ) comprised of shunt-connected three phase transformer banks that is referenced as complete units ( 21 ,  22 , and  23 ) on  FIG. 3 . 
           [0030]      FIG. 5  illustrates a remote monitoring system. 
           [0031]      FIG. 6  is a graph showing test results of a surge suppressor unit installed on a three phase circuit when subjected to an E1 EMP pulse component. 
           [0032]      FIG. 7  is a graph showing test results of a surge suppressor unit installed on a three phase circuit when subjected to an E2 EMP pulse component. 
           [0033]      FIG. 8  is a graph showing test results of a surge suppressor unit installed on a three phase circuit when subjected to an E3 EMP pulse component. 
           [0034]      FIG. 9  is a graph showing test results of a surge suppressor unit installed on a three phase circuit when subjected to an E3 EMP pulse component with the threat pulse removed. 
       
    
    
       [0035]    Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import. 
       DETAILED DESCRIPTION 
       [0036]    Referring to  FIGS. 1A-1C , a generalized power distribution system  10  is shown which discloses various power system components at the grid level which supply power to individual consumers at the facility level. For purposes of this disclosure, the facility level includes industrial and factory facilities and the like, as well as residential facilities such as homes and apartment buildings. These structures include various types of power consuming devices or power consumers such as various types of equipment, motors and appliances. Stand-alone power consuming devices are also supplied by the power grid, such as street lighting, traffic signals, and other power consumers. 
         [0037]    More particularly, the power distribution system  10  includes a transmission grid  11  at high voltage levels and extra high voltage levels, and a distribution grid  12  at medium voltage levels, which in turn supplies lower power at the facility level to residences, factories and the like.  FIG. 1B  shows various power supply sources which generate power at extra high voltages such as a coal plant, nuclear plant and a hydro-electric plant. These may supply power through step-up transformers  13  to an extra-high voltage transmission grid  14 . This grid  14  may in turn connect to a high voltage grid  15  through a network of transformers  16 , which grid  15  is connected to various grid facilities such as an industrial power plant, factory, or a medium sized power plant through respective networks of transformers  17 . Generally, medium voltage refers to the range of 10 kV-25 kV or higher which is typically carried in the distribution grid and may include generation voltages, high voltage refers to the range of 132 kV-475 kV as might exist in the transmission grid, and extra high voltage is in the range of 500 kV-800 kV, which also is typically carried in the transmission grid. These grid level voltages are significantly higher than the low voltages present within a facility or other similar structure. 
         [0038]    The transmission grid  11  may in turn connect to a medium voltage distribution grid  12  ( FIG. 1C ) through a network of transformers  18 . In turn the residential grid  12  may include various facilities such as city power plants, industrial customers, solar farms, wind farms, agricultural farms, rural networks of residences or city residential networks. Various transformers  18  are provided to interconnect these components of the power distribution system  10 . Generally, the present invention relates to a surge suppressor system which is installed at various locations within the power distribution system  10  to provide grid level surge suppression and thereby protect the various facilities supplied with power from the power distribution system  10 . These various transformers may be of various types and configurations such as step-up and step-down transformers, as well as substation transformers installed in substations or delivery transformers which serve to supply individual customers. 
         [0039]    The invention relates to a system of voltage surge suppressor units  20  that are installed at various locations on the power distribution grid  10  to provide three-phase, grid level protection to various facilities which receive power from or supply power to such grid  10 .  FIG. 3  generally illustrates a system of multiple surge suppressor units  20  which are differentiated from each other in  FIG. 3  by reference numerals  21 ,  22  and  23 . These surge suppressor units  21 ,  22  and  23  are sized for the particular installation location and the voltage levels present within the power distribution system  10  at such locations. Generally, the power grid uses various transformers described above, with the representative grid transformer  24  of  FIG. 3  being one of the various transformers used in the transmission grid  11  or distribution grid  12 . The transformer  24  includes a primary side coil  24 P which is connected to three power lines  25 A,  25 B and  25 C which supply power, for example, from a generation plant or the like to the grid transformer  24 . The transformer  24  includes a secondary side coil  24 S which connects to transmission lines  26 A,  26 B and  26 C for supplying power to downstream components of the power grid. In this exemplary embodiment, the transformer  24  steps up the power from 6 kV received from the generation side power lines  25 A,  25 B and  25 C to 300 kV as supplied to the grid power lines  26 A,  26 B and  26 C. It will be understood that voltages for the primary and secondary sides of the transformer  24  can vary depending upon the location within the power grid, wherein the voltage levels can be medium or high voltages. 
         [0040]    The surge suppressor unit  21  connects to the generation power lines  25 A,  25 B and  25 C and the primary side coil  24 P to protect against the various transient conditions described above which thereby protects the primary coils  24 P and the upstream power generators and any upstream grid components and equipment. The surge suppressor unit  22  in turn connects to the grid or transmission power lines  26 A,  26 B and  26 C and the secondary side coil  24 S to protect against the various transient conditions described above which thereby protects the secondary coils  24 S as well as the downstream transmission lines  26 A,  26 B and  26 C as well as any connected grid equipment and components. Also, the surge suppressor unit  23  may be a 480V unit or other suitable voltage level suitable to protect system circuitry and logic. 
         [0041]    Referring to  FIG. 4 , each surge suppressor unit  21 ,  22  and  23  can generally use the design of the surge suppressor unit design  20  ( FIG. 4 ) that comprises a series of shunt-connected three phase transformer banks  31 ,  32  and  33  that are designed to correct phase neutral voltage imbalances by feeding them back onto themselves and/or draining the imbalances off to the integrated resistor bank that is wired to the secondary side of the system as also shown in  FIG. 4 . Each transformer bank  31 ,  32  and  33  includes primary coils  31 P,  32 P and  33 P which connect to and receive power from one of the power transmission lines L 1 , L 2  and L 3  of the system, which may be at the medium or high voltages present in the power grid. The primary coils  31 P,  32 P and  33 P also connect to ground  34 . The lines L 1 , L 2  and L 3  may for example be connected to transmission lines  26 A,  26 B,  26 C ( FIG. 3 ) and supplied by power generator and mega transformers shown in  FIG. 4 , or lines  25 A,  25 B,  25 C in the example of  FIG. 3 . 
         [0042]    Each transformer bank  31 ,  32  and  33  also includes secondary coils  31 S,  32 S and  33 S which connect in series together and have a resistor  35  connected in series therewith. The series connected resistor  35  provides both noise filtering and a discharge path for energy during a power down whether intentional or caused by a natural occurrence. The resistor  35  also helps to drain system energy to prevent an arc-flash since an arc flash is a series phenomenon. By holding up the remaining phases during a fault, voltage buildup cannot form and simply allows circuit protection to open the circuit without a flashing event. This enhanced stability ensures cleaner electron flow and renders the flow safer for components and personnel alike. In other words the surge protection unit  30  balances the voltage on the “load” side. Since the flash is inherently on the “source” side, the voltage across the arc is minimal and the arc will be suppressed. 
         [0043]    Each surge suppressor unit  20  utilizes a circuit breaker  36  governing power from each of the lines L 1 , L 2  and L 3  that can be programmed to rapidly reset and can be made scalable to medium and high voltage requirements. The circuit breaker  36  also may be manually operated for installation and replacement of the surge suppressor unit  20 , or another switch device could be included to provide manual switching of the surge suppressor unit  20 . Depending of the requirements of the utility organization, added protection, in the form of Metal Oxide Varistors, can be series piped in as a secondary circuit as severe over voltage occurs. 
         [0044]    With this construction, the surge suppressor unit  20  thereby balances phase voltages with respect to ground by pushing clean phase shifted current into the phase with the lowest phase voltage. The components preferably are matched single phase transformers  31 ,  32  and  33  and in this permanent solution are sized to the voltage class and kVA in which the particular surge suppressor unit  20  will be employed. The voltage specification determines the appropriate turn ratios needed to properly size each surge suppressor unit  30  to its installation location. All three transformers  31 ,  32 , and  33  are spaced from one another by IEEE standards to prevent arcing or magnetic flux between each phase. Depending on the specific requirements, the surge suppressor units  20  of the invention may utilize underground installation with oil/coolant immersed resistor banks  35  and oil cooled transformers  31 ,  32 ,  33 . These options would allow for closer spacing (smaller footprint) and require less mechanical or free air cooling. These options would also remove equipment from line of sight hostilities. 
         [0045]    During installation, each surge suppressor unit  20  is wired in parallel to the power system, for example, as seen in  FIG. 3 . Further, a surge suppressor unit  20  such as unit  22  in  FIG. 3  may protect from the secondary side  24 S of a power transformer  24  to the primary side of the downstream transformer to provide extended protection extending from the surge suppressor units  20  to other power components connected thereto. For example, a surge suppressor unit  20  may protect from the secondary side of an LPT down to the primary windings of the next step down transformer. Additional surge suppressor units  20  would be installed on the next portion of the stepped down power system beginning with the secondary of that distribution transformer down to the primary on the next transformer and so on. Each surge suppressor unit  20  would be engineered and constructed to operate with the hookup voltage and the VA rating of the transformer it is designed to protect, such that different sized and rated surge suppressor units  20  would be installed in the power grid depending upon the location of installation. This extended protection is also true from the generation source to the primary side  24 P on the initial transformer  24  which is protected by the surge suppressor unit  21  in  FIG. 3 . All connected components would be protected, and the surge suppressor unit  20  of the present invention would stabilize imbalances whether caused by downstream activity or directly on line. 
         [0046]    Further, no power system would need to be turned off to connect the surge suppressor units  20 . The circuit breaker  36  or other suitable disconnect device  36 A can be manually operated such that utility linemen could hot tap the surge suppressor devices  20  into the system and then engage each surge suppressor unit  30  by using the disconnect switch  36 A. 
         [0047]    This system of surge suppressor units  20  provides power factor correction (PFC) by optionally introducing power regulating products (e.g. capacitors  37 ) to help streamline the power current making the energy more efficient. 
         [0048]    Preferably, the surge suppressor unit  20  ( FIG. 4 ) also includes one or more appropriate sensors  38 , which preferably include a current sensor. The sensor  38  connects to a control system  39  for detecting and monitoring the sensor  38 . The control system  39  may also include remote (web-based) diagnostic and reporting features such as that shown in the data display  40  of  FIG. 5 . The data display  40  may be located remote from the various surge suppressor units  40  for monitoring by utility personnel, such as through a computer terminal. The data display  40  preferably shows information regarding faults (imbalances) that are proactively communicated and can be monitored from off-site locations. The data display  40  includes several display graphs  41 ,  42 ,  43  and  44  which can display various types of data. This real time status reporting would provide significant information and data including but not limited to: 
         [0049]    Voltage by phase 
         [0050]    Amps by phase 
         [0051]    Harmonics by phase 
         [0052]    Oil/Coolant Temperature 
         [0053]    Ground fault indicator (by phase and the severity of each occurrence). 
         [0054]    The control system  39  may include alarms for every data point, which alarms could be customizable so as to trigger utility response to multiple remote locations. This is critical with grid level power substations that are often un-manned and/or in remote settings. Every data point can be captured, stored, and maintained with data storage means within the control system  39  for historical tracking and reference so as to allow for both historical trend analysis and specific search capability. 
         [0055]    Focusing on voltage allows the invention to address each of the 5 Common Power Issues discussed above. Transients are the brief voltage spikes that occur regularly and may last only a few cycles. The inventive system would take the surplus voltage in the same waveform and electromagnetically feed it back on itself with the same intensity through the transformers  31 ,  32  and  33 . Even with a power analyzer one could see that disturbances placed directly on line are completely mitigated. 
         [0056]    Interruptions have many causes but the damage occurs in the brief moments as a system loses power and motors which wind down turn into mini generators sending inappropriate voltages to connected loads. The system of the invention would not prevent sustained power losses but would prevent damage to loads by allowing a softer landing should an outage occur due to the interaction of the transformers  31 ,  32  and  33  and the resistor  35 . 
         [0057]    The invention will also reduce the harmful effects of voltage instability like sags and swells or under/over-voltage at a grid level. The primary sides  31 P,  32 P and  33 P of the transformers  31 ,  32  and  33  and their adjoining secondary sides  31 S,  32 S and  33 S constantly stabilize the voltage discrepancy. If there is a sustained swell, the excess power is harmlessly drained off to the integrated resistor bank  35  that is series wired on the secondary side of the system. 
         [0058]    Waveform and frequency variations might best be described as noise on the line from massive magnetic forces. These magnetic hits to the grid can cause damage to generators, transformers, auto tapping devices, and connected loads throughout. High frequency noise from hostile EMPs change the normal 60 Hz flow of electrons which may wreak havoc on infrastructure. Depending on the severity or proximity to such hostilities, damage could range from loss of end user electronic devices to the overheating of the stators on utility generation plants or power transformers. The surge suppressor units  20  of the present invention would act as a gatekeeper, suppressing any frequency above or below the 60 Hz range. Damage to grid components could occur in an instant without the system of the present invention but since it operates only on 60 Hz waveforms it routs the inappropriate waveform to the integrated resistor bank  35  at the exact speed of the infraction. The invention, therefore, rectifies disturbances that are out of specification and harmonizes everyday activity. 
         [0059]    The system of the present invention provides significant advantages over prior surge suppressor devices. For example, the system of the present invention is designed for medium and high level voltages with a targeted application for grid system protection. Many prior surge suppression devices were designed for low voltage systems such as an industrial or residential setting that are self-contained which have no “cascading” issues or additional sources of power to be concerned about. The present invention can accommodate the unique requirements of the power grid. 
         [0060]    Further, each surge suppressor unit  20  does more than protect a single device. Rather each of the surge suppressor units  20  is wired in parallel at appropriate locations on the power grid to protect both sides of grid level substations, power delivery systems, and generation plants.  FIG. 3  provides an exemplary illustration of the extended protection provided by individual surge suppressor unit. 
         [0061]    Further, the provision of a circuit breaker  36  and disconnects  36 A in the surge suppression units  20  allows the invention to be scaled to medium and high voltage grid systems and facilitates hot tapping of each unit  20  during installation or replacement. The surge suppressor unit  20  also allows for the inclusion of Metal Oxide Varistors, which can be series piped in as a secondary circuit, to add specific grid level protections for severe over-voltages. 
         [0062]    More particularly, a surge suppressor device according to this design has been tested at defined voltage levels under conditions representing an EMP of varying wavelength/shape and frequencies directly on line through injection. This testing was conducted with resistive and inductive loads using Mil-spec 188-125-1 and Mil-Std-2169 test standards and equipment to represent grid level protection. Thousands of volts were injected into a surge suppressor unit designed according to surge suppressor unit  20  described above and a connected power system wherein threat pulses were identified, clamped and drastically reduced every time through multiple individual test events.  FIGS. 6-9  illustrate test data from such tests. 
         [0063]    Generally as to an EMP such as a nuclear generated EMP, such pulses are considered to include three pulse components commonly designated as E1, E2 and E3. The E1 component is considered to be the quickest and can induce high voltages in an electrical system. The E2 component is an intermediate pulse beginning at a short time after initiation of the electromagnetic pulse and ending soon thereafter. This pulse is considered to be similar to a lightning strike but of a lesser magnitude. The E3 pulse component is longer and slower and is considered most similar to a solar flare. The E3 pulse component is the most troublesome component to deal whether it is generated by a nuclear EMP or a solar flare, and current technologies do not handle the E3 pulse component and suitably protect grid systems. 
         [0064]    In EMP testing of the present invention, the surge suppressor unit  20  has shown to handle and protect against all three pulse components, namely E1, E2 and E3. The surge suppressor quickly clamps on EMP pulse threats within millionths of a second and reduces the severity of the threat to safe levels. For example, the unit mitigated the E1 pulse instantaneously and eliminated the threat within 1.3 μsecs, the unit mitigated the E2 pulse instantaneously and returned the phases to “normal” within 0.002 seconds, and the unit also mitigated the E3 pulse instantaneously and returned the phases to “normal” within 0.002 seconds. The same device continued to operate throughout all tests and suffered no damage such that it can be installed and performs through multiple EMP events. 
         [0065]      FIG. 6  illustrates a graphical representation of the test results for the three phases and their reaction to the injected E1 pulse which was injected under test conditions recreating such a pulse component. This graph compares the kAmps detected in the system phases against the time measured in pseconds with pulse initiation at time 0.  FIG. 6  shows the E1 pulse injection test from time −1.0 to 3.5 μsecs. The surge suppressor unit was connected to a three phase circuit wherein the system under normal operating conditions was a 480 v operating system with 6000 watts of load. The test injected 20,000 volts at 1500 Amps to simulate an E1 waveform. The height of the threat pulse  80  maxes out at nearly 1500 Amps (1.5 kA) on a single phase and lasts for over 1.9 micro seconds. The threat pulse  80  is injected onto the operating system, and the pulse is shown with a sudden spike with a diminishing tail. The darker Phase A load  81  and the lighter colored Phase B load  82  create an immediate dip to help correct the imbalance or resultant E1 spike on the Phase C load  83 . The Phase C carried the wave from the injected load, but mitigates the impact by pushing the load back on to Phases A and B. Phases A, B and C of the surge suppressor unit have compensated for the threat pulse by correcting the wave against itself or in other words balances the pulse against the other two phases creating a real time correction that can be seen in the graphs. As a result, the surge suppressor unit immediately mitigates the surge and begins reducing the magnitude and width within 0.1 μsec. The threat is kept to less than 500 amps at its peak as is reduced to below 250 Amps within 0.2 microseconds (70% reduction in amplitude). By reducing the height (magnitude/amplitude) and the width (duration) by such a wide margin, the surge suppressor renders the E1 threat harmless to the grid components. The threat is completely eliminated by 1.3 μseconds. 
         [0066]      FIG. 7  shows the graphical results of the surge suppressor unit responding to an injected E2 threat. The threat pulse is shown as graph line  90  wherein the threat pulse is injected onto Phase C shown by line  91  at approximately 5 kV with a 6 kw load being present. The pulse is shown as a sudden spike with a diminishing tail. The Phase A load  92  and Phase B load  93  create an immediate dip to help correct the imbalance on the Phase C load  91  which exhibits a spike. Phase C  91  is already mitigating the impact by pushing the load back onto Phase A  92  and Phase B  93 . Phase C  91  peaks at 109 Amps compared to the 260 Amp peak of the threat  90 . All three phases are corrected and back in phase within 0.002 seconds from the initial threat being injected on the line. All three phases  91 ,  92  and  93  are in alignment prior to the threat  90  being injected at time 0. All three phases are back in phase very quickly from the initial E2 threat being injected on the line. Therefore, the surge suppressor unit also can readily handle the E2 pulse component or a pulse exhibiting similar characteristics. 
         [0067]    The surge suppressor unit was also tested under an E3 pulse component which is shown in  FIGS. 8 and 9 .  FIG. 8  shows the graphical results with the threat pulse  100  injected onto Phase C  101  at approximately 2 kV with a 6 kw load. The threat pulse is clearly shown in  FIG. 8  with a sudden spike and corresponding waves. Due to the scale of the graph in  FIG. 8 , the reaction of the phases is not entirely clear. As such,  FIG. 9  is provided with the threat pulse  100  omitted so that the scale of the system phases can be increased for clarity. As seen in  FIG. 9 , Phase C  101  has an immediate spike. However, the Phase A load  102  and the Phase B load  103  create an immediate dip to help correct the imbalance on the Phase C load  101 . Phase C already mitigates the impact of the threat pulse  100  by pushing the load back on to Phase A  102  and Phase B  103 . Phase C  101  peaks at 109 Amps compared to the 1710 Amp peak of the threat pulse  100 . All three phases  101 ,  102 , and  103  are corrected and back in phase within 0.002 seconds from the initial threat pulse  100  being injected on the line. All three phases are in alignment prior to the threat pulse  100  at time zero, and back in alignment within 0.002 seconds, such that the surge suppressor can readily handle the E3 pulse component. 
         [0068]    As such, the inventive surge suppressor system can prevent the need to shed load in the presence of E3 activity or solar flare activity on the grid by correcting the flattening of the AC waveform. By maintaining 3 perfectly balanced phases where the vectors are 120 degrees out of phase, the surge suppressor eliminates the need to reduce LPT loads to prevent overheating and damage from half cycle saturation. 
         [0069]    Preferably, the surge suppressor unit never routes surplus energy from these electromagnetic forces to ground, and instead, said energy is thrown against the incoming surge at the speed of the infraction. Much like a mirror instantaneously rebounds a beam of light, the surge suppressor system rebounds pulse threats to mitigate the inrush of power regardless of the magnitude. 
         [0070]    The surge suppressor system can be installed nearly anywhere within the power distribution grid and still protect the entire portion of the circuit. This means a surge suppressor unit could be installed midway between the LPT and the next step down transformer which eliminates the need for a new piece of equipment in an already crowded space at the power source. 
         [0071]    Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.