ABB-Código de Red - Banco de Capacitores y Filtros de Armónicos

Introduction to the Conference

Welcome and Overview

• The National Union of Electromechanical Constructors welcomes participants to an online conference on the "Network Code for Capacitor Banks and Harmonic Filters."

• ABB's engineer, Dan Salazar, introduces himself and his expertise in power factor solutions and harmonic distortion.

Understanding the Network Code

Background of the Network Code

• The Network Code gained attention last year despite being published years earlier; it stems from a reform that changed energy supply dynamics.

• EFE (Electricity Federal Entity) transitioned from leading energy commercialization to becoming just another electricity supplier under new regulations.

Structural Changes in the Energy Sector

• The new structure involves collaboration between EFE, the Ministry of Energy, and CRE (Energy Regulatory Commission), altering previous roles in energy generation, control, transmission, and distribution.

Regulatory Framework of the Network Code

Key Features of the Network Code

• Issued by CRE on April 8, 2016, it outlines technical regulations necessary for maintaining a healthy national electrical system.

• Focus areas include improving energy quality through voltage stability, frequency regulation, power factor correction, harmonic distortion management, current imbalance coordination, etc.

Implementation Timeline

• The code became effective on April 9, 2016. A three-year compliance period was established which concluded in April 2019.

Objectives of the Network Code

Goals for Electrical System Improvement

• The primary aim is to ensure a reliable and efficient national electrical system where all companies interconnect seamlessly.

Importance of Power Factor and Harmonics

• Enhancing power quality is crucial; poor power factors often result from user-induced inductive loads while harmonics are generated by electronic equipment like speed variators and computers.

Impact of Power Factor on Efficiency

Understanding Power Factor Metrics

• A low power factor indicates inefficiency; e.g., a factor of 0.7 means only 70% of purchased energy converts into work while 30% is wasted as heat.

Benefits of Improving Power Factor

• Raising the power factor close to unity minimizes energy waste significantly—aiming for efficiency near 100%.

Challenges with Harmonic Distortion

Growth in Electronic Equipment Usage

• Increased automation leads to more electronic devices introducing harmonic pollution into systems; this can affect all connected entities negatively.

Consequences for Connected Systems

Network Code and Its Impact on Electrical Systems

Addressing Contamination in the National Electric System

• The network code aims to improve reliability by controlling contamination that can affect neighboring areas.

• Without proper management of harmonic contamination, the electrical grid could face chaos, distributing this contamination throughout the system.

Technical Requirements for Interconnection

• There are two technical requirement manuals within the network code; one focuses on interconnecting new power plants to the national electric system.

• This manual applies to companies looking to connect as new entities, including expansions of existing plants. Compliance with these requirements is essential before interconnection can occur.

Studies Required for Interconnection Approval

• Various studies must be conducted prior to interconnection, including steady-state analysis, transient behavior, protection coordination, and energy quality assessments related to harmonic distortion.

• These studies utilize software called PSS (Power System Simulator), which is validated by regulatory authorities (CREE). The results must be submitted for approval before proceeding with interconnections.

Case Study: Harmonic Levels Affecting Interconnection

• A case was presented where a plant upgraded from 23 kV to 85 kV but faced issues due to high harmonic levels detected during monitoring, preventing successful interconnection until those levels were reduced.

• This highlights the importance of conducting thorough studies beforehand to ensure compliance with national standards and avoid costly delays in project implementation.

Additional Technical Requirements for Load Centers

• The second technical requirements manual addresses connections for load centers already operational within the national electric system and having an established energy demand contract.

• It specifies compliance deadlines that cannot exceed three years from its introduction in April of last year; failure to comply may result in penalties from CREE.

Clarification on Voltage Levels and Compliance Guidelines

• Confusion arose regarding which voltage systems (high vs medium tension) were subject to compliance under the network code; CREE published a guide clarifying these requirements based on voltage levels at the end of March last year.

• For medium tension systems connected at various voltages (13 kV - 34 kV), users must meet specific technical requirements concerning voltage stability, frequency control, short-circuit protections, information exchange protocols, and energy quality metrics like current imbalance only at this stage.

Stricter Regulations for High Tension Users

• Users connected above 35 kV (e.g., 69 kV - 230 kV) face stricter regulations requiring adherence not only to previous standards but also additional measures regarding power factor and harmonic distortion monitoring compliance as part of their operational obligations under the network code.

Evaluating User Compliance Across Voltage Levels

• An evaluation revealed approximately 1,000 users connected at high tension versus around 400,000 at medium tension; focusing solely on high-tension users would undermine achieving overall objectives set forth by the network code due to their small proportion relative to total users affected by these regulations.( t =844 s )

This structured approach ensures clarity while providing detailed insights into critical aspects discussed in relation to electrical systems' regulation through network codes.

Authorization Process and Updates on Network Code

Current Status of Authorization

• The authorization process is in its final stage but has not yet been enacted. It was anticipated to be active this year, but delays due to the pandemic and resource limitations have hindered progress.

Upcoming Updates to the Network Code

• The regulatory body (CRE) is required by law to update the network code every two years. An update is expected in 2020, which will include significant changes for users connected at medium voltage levels.

Compliance Requirements for Medium Voltage Users

• Users with a contracted demand of 1,000 kilowatts or more will need to comply with new requirements regarding power factor and harmonic distortion. This change aims to enhance overall performance within the national electrical system.

Technical Requirements Overview

• As per documents related to the 2018 network code, medium voltage load centers exceeding 1,000 kilowatts will have a two-year compliance period for technical requirements similar to those for high-voltage plants. Currently, only the 2016 publication's requirements are officially in effect.

Monitoring Power Factor Changes

Power Factor Compensation and Automatic Technologies

Automatic Power Factor Correction

• The implementation of automatic technologies allows for the adjustment of power factor by measuring load variations and automatically connecting or disconnecting capacitors as needed.

• For instance, if a plant's load decreases significantly (e.g., on a Saturday), the automatic bank detects this change and disconnects unnecessary capacitors, optimizing energy use.

Compliance with Harmonic Distortion Standards

• The network code mandates compliance with specific harmonic distortion levels, referencing tables similar to IEEE 519 standards until an official Mexican norm is established.

• Different voltage levels dictate varying harmonic limits; for example, plants under 69 kV have limits ranging from 5% to 20%, while those above 161 kV face stricter limits of 2.5% to 3.75%.

Importance of Monitoring and Analysis

• To determine compliance with harmonic limits, studies must assess short-circuit power and load current, requiring detailed monitoring of kilowatt consumption and harmonic distortion levels.

• By calculating the ratio of short-circuit current to load current, facilities can identify their specific harmonic limit based on predefined ranges.

Detailed Harmonic Analysis Requirements

• The network code not only requires total demand distortion but also specifies individual harmonic levels that must remain below certain thresholds (e.g., harmonics below the eleventh should be under 7%).

• Comprehensive studies are necessary to analyze each harmonic component individually rather than just overall distortion percentages.

Financial Implications of Non-compliance

• Non-compliance with the network code can lead to significant financial penalties for companies, impacting their gross income directly.

• Penalties range from 2% to 10% of previous year's gross income based on severity; factors influencing penalty amounts include user impact and duration of non-compliance.

Strategies for Mitigating Penalties

• Companies can avoid severe penalties by actively monitoring energy quality and implementing corrective measures in line with network code requirements.

• Proactive engagement in energy quality studies helps mitigate risks associated with potential fines due to non-compliance.

Additional Penalty Structures

• A second type of penalty exists for outright non-compliance with the network code, which could amount to between 50,000 and 200,000 minimum wages depending on regulatory discretion.

Understanding Compliance with the Network Code

Importance of Avoiding Penalties

• The discussion begins with the financial implications of compliance, highlighting that avoiding penalties can save significant amounts, such as 5 million pesos.

• Emphasis is placed on assessing each plant's status and taking necessary actions to meet technical requirements outlined in the network code.

Compliance at Connection Points

• The network code mandates compliance at the interconnection point between a company and the national electrical system, marked as a critical area (the "red point").

• All invoices from service providers require monitoring of power factor at this connection point, indicating its importance for compliance.

Solutions for Power Factor Issues

• Various solutions are discussed for addressing power factor distortion and harmonic distortion by connecting equipment at different voltage levels (medium or low tension).

• Challenges arise when existing substations are unable to accommodate additional equipment due to space constraints; alternative solutions may involve low-tension setups.

Technical Considerations for Harmonic Distortion

• The ideal solution involves addressing harmonic distortion directly at its source or from loads affecting power factor.

• While capacitors are commonly used for compensation, other methods like transformers or panels can also provide benefits beyond just meeting network code requirements.

Benefits of Low-Tension Solutions

• Installing equipment closer to load points ensures better quality energy delivery and compliance with network codes.

• A focus on low-tension solutions allows companies to maintain operational efficiency even if some components fail, unlike high-tension setups where failure could lead to complete downtime.

Flexibility in Compliance Methods

• Companies have flexibility in how they achieve compliance; multiple transformers may require individual solutions versus a single solution for medium tension.

• Cost comparisons show that while medium tension might seem cheaper initially, low-tension systems offer redundancy and reliability during failures.

Maintenance and Reliability Concerns

• If a capacitor fails in a high-tension setup, it could jeopardize overall compliance; however, low-tension systems allow continued operation despite individual component failures.

• This redundancy is crucial for maintaining adherence to network code requirements over time without significant interruptions.

Decision-Making Based on Current Conditions

• The network code does not dictate specific methods for achieving compliance but allows users discretion in choosing their approach (capacitors, filters).

• Before implementing any solution, thorough assessments of current processes regarding power factor and harmonic distortion must be conducted.

Comprehensive Review Process

• Conducting detailed studies before making decisions ensures informed choices about which issues need immediate attention based on severity.

Understanding Power Factor Compensation Solutions

Overview of Measurement and Monitoring

• The discussion emphasizes the importance of having measurement equipment to monitor voltage, current, power, and harmonic distortion. This data can help create a network code folder to assess these values effectively.

Capacitor Solutions for Power Factor Correction

• Fixed capacitors, automatic banks, and active filters are introduced as solutions for improving power factor. However, fixed capacitors may not be viable due to their inability to adapt dynamically to load changes.

• Local compensation can be achieved by adding fixed capacitors when new motors or additional loads are introduced. It is crucial that these capacitors disconnect when the motor is off to prevent overcompensation.

Safety Mechanisms in Capacitor Design

• Cylindrical capacitors have built-in safety features that disconnect them if internal pressure exceeds safe limits due to harmonic contamination heating up the capacitor.

• If a capacitor fails without proper safety measures, it can cause significant damage due to short-circuit currents combined with discharge currents that can reach up to 30 times its nominal current.

Discharge Resistance and Mechanical Safety Features

• All capacitors should include discharge resistors to ensure they do not remain charged after disconnection. This prevents dangerous shocks from residual charge.

• A unique mechanism in some cylindrical capacitors ensures all three phases disconnect simultaneously if internal pressure becomes dangerously high, enhancing safety during operation.

Advanced Capacitor Designs for Enhanced Safety

• Rectangular capacitors are designed with steel enclosures filled with vermiculite, which acts as an insulator and fire retardant by absorbing oxygen in case of a fire within the capacitor.

Automatic Capacitor Banks and Power Factor Correction

Overview of Automatic Capacitor Banks

• The current flows infinitely to capacitors, which can discharge with significant force. These capacitors are used in automatic banks that measure load and disconnect or connect based on the load's status.

Measurement and Control Systems

• The system measures every five minutes, ensuring that the power factor remains between 95% and 1%. Reliable equipment is essential for these operations, utilizing controllers that act as meters with outputs to contactors.

Importance of Monitoring Equipment

• The controller not only connects capacitors but also provides measurements, programming, and communication capabilities. This allows for quick decision-making if the power factor drops unexpectedly.

Electrical Parameter Visualization

• Users can visualize electrical parameters such as kilowatts, voltages, currents, and harmonic spectra through monitoring equipment. This comprehensive view aids in understanding plant consumption patterns.

Compensation Mechanisms in Automatic Banks

• Automatic banks compensate for power factor using contacts. When load changes occur, they connect or disconnect capacitors at intervals (40 seconds), allowing transients to stabilize before further connections are made.

Handling Rapid Load Changes

• In applications with rapid load fluctuations (e.g., welding machines), traditional contact-based compensation may be inadequate. Thyristor-based banks provide a faster response to maintain power factor stability.

Challenges with Aging Capacitor Banks

Longevity of Capacitor Equipment

• Many companies have capacitor banks that are over a decade old but may no longer suit their current operational needs due to increased electronic loads like variable speed drives.

Misconceptions About Harmonic Filters

• Often businesses request harmonic filters when the real issue is an outdated capacitor bank unable to handle modern electronic loads effectively.

Impact of Harmonics on Power Factor

• While capacitor banks do not generate harmonics themselves, they can amplify existing distortions if not properly assessed before installation.

Solutions for Managing Harmonics

Use of Reactors in Capacitor Banks

• To mitigate harmonic distortion while improving power factor, reactors are added in series with capacitors. This setup acts as a barrier against network contamination from harmonics.

Visual Representation of Solutions

• A table illustrates how adding reactors helps control voltage distortion while maintaining desired power factors across various configurations.

Understanding Harmonic Distortion and Reactors

The Role of Reactors in Reducing Harmonic Distortion

• The reactor acts as a filter, allowing clean water to flow into the glass while reducing harmonic distortion from 7% to 5.5%. This is due to the heat loss of harmonics attempting to pass through the reactor.

• While the reactor reduces distortion by about 1-2%, it does not eliminate it entirely. Measurements with and without capacitors reveal that often, the capacitor itself is the source of distortion.

• Replacing an old capacitor with a new one can completely eliminate distortion, ensuring compliance with network codes which may set limits at 8%.

Importance of Measurement and Capacitor Selection

• Proper measurement is crucial for selecting reactors; different types protect against specific harmonic frequencies (e.g., some react to harmonics above 3.8, others above 2.4).

• Many clients mistakenly believe that simply adding more capacitors will solve their power factor issues without addressing harmonic distortion.

Understanding Harmonics

• Harmonics are multiples of the fundamental frequency; in Mexico, this frequency is typically 60 Hz. Electronic equipment operates at higher frequencies (e.g., 180 Hz corresponds to third harmonic).

• Odd harmonics (3rd, 5th, and 7th) are particularly problematic as they can cause significant contamination in electrical systems.

Visualizing Harmonics

• A sine wave represents a clean signal at 60 Hz; superimposed red waves illustrate odd harmonics (3rd, 5th, and 7th), which disrupt this purity.

• Even harmonics tend to cancel each other out due to symmetry in their waveforms, whereas odd harmonics do not have this property.

Effects of Harmonic Distortion on Equipment

• Electronic devices rely on sine waves; any deformation leads to noise that can cause malfunction or abnormal operation.

• Each harmonic has distinct effects on motors; for instance, negative sequence currents can reverse motor direction unexpectedly leading to increased wear and tear.

Consequences for Motors and Capacitors

• Motors experiencing frequent changes in direction due to harmonic interference may suffer from overheating and require more maintenance.

Understanding Harmonic Distortion in Electrical Systems

The Impact of Harmonic Distortion

• Harmonic distortion generates excess heat, which can lead to capacitor failure. Both current and voltage distortions are dangerous but cause different types of damage over time.

• Current distortion results in long-term damage by aging installations, heating feeders, and degrading conductor properties, leading to erratic current spikes. Voltage distortion alters the power supply for equipment.

Effects on Electronic Equipment

• Electronic devices are primarily affected by changes in power supply due to harmonic distortion. This can result in frequent damage to electronic circuit boards.

• High temperatures in transformers operating at 50% capacity may also be attributed to harmonic distortion.

Solutions for Eliminating Harmonics

• Active filters are employed to counteract harmonic distortion by monitoring the network and generating opposing harmonics.

• These filters require rapid response technology that can identify specific harmonics (e.g., third, fifth, seventh) and inject them back into the system to neutralize their effects.

Case Study: Successful Implementation of Filters

• A case study showed a company with an 8% current limit measuring 16% harmonic distortion. This led to waveform deformation and significant heat generation from excessive currents.

• Identifying present harmonics (primarily fifth and seventh), an active filter was configured to reduce the initial 16% distortion down to 3.7%, improving voltage quality as well.

Monitoring and Adjusting Filter Performance

• By eliminating harmonic currents, only working currents remain, further reducing voltage distortion. The goal is maintaining levels below 8%.

• The reduction of harmonic levels from 3.7% could potentially go lower with larger filters; however, operational efficiency is prioritized over excessive filtering.

Advanced Filtering Techniques

• Post-filtering results showed significant reductions in both fifth (from 80A to 1A) and seventh harmonics (from 47A down to negligible levels).

• Additional harmonics can be targeted if the filter has sufficient capacity; up to twenty harmonics can be selected for elimination based on system needs.

Importance of Accurate Measurements

• To determine necessary filtering solutions accurately, real-time measurements during normal operation are essential for assessing circulating harmonic currents.

Understanding Harmonic Distortion in Industrial Systems

Use of Filters for Harmonic Distortion

• A three-phase, four-wire filter is recommended for specific load types, particularly industrial loads with variable speed AC drives and robotics.

• For larger industrial loads requiring 200 amperes of harmonic reduction, a master-slave configuration can be implemented using two 100 ampere modules to achieve the desired capacity.

• More robust filters are necessary for heavy-duty applications like cement plants that have high levels of harmonic distortion due to large DC drives.

Case Study on Severe Harmonic Distortion

• An example highlights a severe case with over 30% harmonic distortion and a current level of 340 amperes, indicating significant issues within the electrical system.

• It's crucial to relate distortion percentages to actual current levels; an 80% distortion at low load may not indicate serious problems compared to higher loads.

Impact of Filtering on Energy Consumption

• The waveform analysis shows significant deformation in current and voltage waveforms, leading to potential electronic equipment failures.

• After implementing filtering solutions, harmonic distortion was reduced from 30% to below 8%, resulting in improved energy quality and substantial energy savings (approximately 100 kilowatts).

Questions and Answers Session Insights

• During the Q&A session, questions arose regarding the reliability of determining short-circuit levels using the Bruce Infinite method for harmonics; it is deemed reliable when complete data isn't available.

• It’s suggested that network studies should ideally use software tools alongside real-time measurements from analyzers across different voltage levels.

Calculating Load Current and Harmonics

• To calculate required load currents versus short-circuit values, monitoring equipment is used over time to establish maximum and average currents.

• In cases where plants are not operational yet, calculations are based on electrical diagrams or plans to estimate total load requirements accurately.

Understanding High Harmonics at Low Demand

Understanding Harmonic Currents in Electrical Systems

The Impact of Load on Current and Distortion

• When a load is removed, the current decreases; however, if the load generating harmonic currents (100 amperes) remains connected, the total current can increase to 200 amperes with a 50% distortion rate.

• The presence of harmonic currents affects the overall system performance. Even if the load is disconnected, residual harmonics may still circulate in the network.

• Reducing the load can lead to an increase in percentage distortion, indicating that managing loads effectively is crucial for maintaining power quality.

Conclusion of Online Conference

• The session concludes with gratitude expressed towards participants and acknowledgment of Dalí's expertise shared during the conference.