Orientador: Sérgio Kurokawa / Resumo: Esta dissertação apresenta um estudo realizado sobre o método de recapacitação de linhas de transmissão por injeção de tensão de terceira harmônica (TTH). O método foi publicado em 2017 por Alaei e Khajehoddin como uma proposta mais economicamente viável de elevar a tensão de transmissão sem a necessidade de alterações nas estruturas das linhas de transmissão. A injeção de TTH em linhas convencionais tem como objetivo provocar um achatamento na forma de onda das tensões de fase, causando uma redução em seu valor de pico. O método se mostra vantajoso pelo fato de que a largura das faixas de servidão e as distâncias entre cabos condutores e solo são especificadas com base no valor de pico das tensões de fase. Logo, a redução da tensão de pico não somente permitiria às estruturas existentes transmitirem maior potência como também possibilitaria a construção de novas torres de transmissão com tamanho reduzido e faixas de servidão mais estreitas, tornando uma proposta economicamente atrativa para as companhias de transmissão de energia elétrica. No artigo em que o método de recapacitação em questão foi proposto, os autores realizam análises de tensões e correntes apenas nos terminais das LTs. A contribuição deste trabalho para os estudos do método de recapacitação por injeção de TTH, consiste nas análises feitas através de um modelo de linha de transmissão a parâmetros distribuídos, que permitiu o monitoramento das tensões de fase ao longo da extensão de linhas com diferentes comp... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work presents a study concerning the transmission line uprating method by injection of third harmonic voltage (THV). The method was published in 2017 by Alaei and Khajehoddin as a more economically feasible proposal to raise the transmission voltage level without the requirement for changes in the structural elements of overhead lines. The THV injection in conventional overhead lines aims to flatten the waveform of the phase voltages, resulting in a reduction in its peak values. This represents a significant advantage, since the specification of right-of-way (ROW) width and ground clearance bases on the peak value of the phase voltages. Therefore, a reduction in the peak voltage would not only allow the existing structures to transmit electricity at higher voltages but also the construction of new transmission towers with reduced size and narrower ROW, making it an economically attractive proposal for electric power transmission companies. In the article in which the referred uprating method was proposed, the authors perform voltage and current analyzes only at the TL ends. The contribution of this work to the studies of the uprating method by THV injection consists in the analyzes made through a distributed parameter transmission line model, which allowed the monitoring of the phase voltages along the extension of lines with different lengths, both at steady-state and during the system switching. The results showed that THV injection causes overvoltage along the extent ... (Complete abstract click electronic access below) / Mestre

Orientador: Edson Bim / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T11:16:01Z (GMT). No. of bitstreams: 1 Bertonha_LeandroCorrea_M.pdf: 4817108 bytes, checksum: 7377641ea7817b2bac41b6c4870c60b2 (MD5) Previous issue date: 2006 / Resumo: Neste trabalho é apresentada a implementação de uma estratégia de controle escalar V/f que mantém o fluxo de entreferro constante em seu valor nominal a partir do controle da relação entre a tensão de terceira harmônica, do estator, presente devido à saturação magnética, e da freqüência elétrica. No caso das bobinas de estator estarem conectadas em Y, a terceira harmônica de tensão é obtida a partir da soma das tensões de fase do estator. Na. presente proposta não é necessário saber a magnitude do fluxo, mas apenas o valor da terceira harmônica de tensão quando o motor opera na sua condição nominal. O método proposto é simples de ser implementado, computacionalmente leve e insensível aos parâmetros do motor. Esta última característica é especialmente atrativa, pois boa parte cios acionamentos elétricos propostos na literatura com controle escalar tem seu desempenho insatisfatório devido à influência da variação da resistência de estator, principalmente quando o motor opera em baixas velocidades. Resultados experimentais mostram que a técnica implementada tem um excelente desempenho em regime permanente, ainda que com carga mecânica, e bom desempenho nos transitórios / Abstract: In this work it is presented the implementation of scalar control V/f technique. It keeps the air gap flux constant in its rated value by the control of the relation between third harmonic voltage, due to saturation, and electric frequency. When the coils are conected in Y. the third harmonic is obtained by the sum of staler phase voltage. We propose that it is not necessary to know the air gap flux magnitude, but only the third harmonic value when the induction motor operates in rated condition. The proposed method is easy to implement, has a light coputational processing and it is not sensitive to motor parameters. This last caracteristic is attractive, because many electric drivers have low performance due to the influence of stator resistence variation, mainly when, the motor operates in reduced speed. Experimental results show the high performance of system in steady state, with applied load, and good performance in dynamic situation / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

Com o surgimento das novas tecnologias aplicadas aos equipamentos e arranjos geométricos das fontes renováveis de energia, o sistema de aterramento passou a operar com correntes de várias frequências, diferentes da componente fundamental. Estas correntes são provenientes das novas cargas não lineares conectadas e das condições de falta, tornando mais difícil a equipotencialização do sistema de aterramento, devido, principalmente, ao seu tamanho e sua geometria. Neste cenário, esta pesquisa tem como objetivo o estudo do comportamento de um sistema de aterramento operando na presença de correntes com distorção harmônica. Para a modelagem do sistema de aterramento teste, foi utilizada a teoria de linhas de transmissão, considerando parâmetros distribuídos, pela qual o condutor foi modelado em porções ao longo de seu comprimento. Para a modelagem e análise do sistema de aterramento foram utilizados o programa ATP (Alternative Transients Program) e uma ferramenta computacional comercial, com o intuito de validar os valores da resistência da malha de aterramento observados. Pelos resultados encontrados, têm-se argumentos para alertar os projetos futuros de sistemas de aterramento para a necessidade e uma melhor análise das situações operacionais passíveis de ocorrência no sistema elétrico que venham a apresentar uma composição harmônica diferente e não desprezível em relação ao componente fundamental. / With the rise of new technology applied to devices and geometric arrangements related to renewable energy sources, grounding systems have started to operate with currents of multiple frequencies, deviating from its fundamental component. These currents come from the connection of new nonlinear loads and fault conditions, which makes the equipotential bonding harder for the grounding system, mainly due to its size and geometry. In this scenario, this research aims to study the behavior of a grounding system operating in the presence of harmonically distorted currents. The transmission line theory was used to model the testing grounding system, based on distributed parameters, through which the conductor was modeled in increments along its length. For modeling and studying the grounding system, the ATP (Alternative Transients Program) and a commercial software tool were used in order to validate the resistance values observed in the grounding grid. Based on the results found, there are arguments to alert future grounding system projects about the need for a better assessment of operational scenarios likely to occur in the electrical system, which may display a different harmonic composition that is not negligible in relation to the fundamental component.

A utilização da energia eólica é ainda recente no setor elétrico e, por isso, apresenta inúmeros desafios na operação e integração dessa nova tecnologia com o sistema elétrico. Desta forma, este trabalho aborda o impacto da injeção de correntes harmônicas que as Centrais de Geração Eólica geram no Sistema Interligado Nacional. Inicialmente, aborda-se a fundamentação teórica e o conceito básico da energia eólica, principalmente em relação ao panorama desta fonte renovável no Brasil e no mundo e, de uma forma sucinta, aborda-se também sobre o aspecto tecnológico dos aerogeradores. Outro aspecto relevante deste trabalho, é o levantamento do estado da arte sobre os conceitos e cálculos das distorções harmônicas, bem como sobre o processo de integração das novas Centrais de Geração Eólica à rede básica. O principal resultado obtido neste trabalho, é o estudo de sensibilidade da distorção harmônica de tensão, no ponto de acoplamento da Central à rede básica de transmissão, frente à variação topológica da rede coletora da Central de Geração Eólica. Para tal estudo, foi modelada uma Central de Geração Eólica e aplicadas as metodologias estudadas no estado da arte. Os resultados obtidos do estudo de sensibilidade, é de grande interesse para os operadores da rede e transmissão de energia elétrica, bem como às geradoras de energia eólica. / The use of wind energy is still recent in the electric sector and, therefore, presents numerous challenges in the operation and integration of this new technology with the electric system. In this way, this work approaches the impact of the injection of harmonic currents generated by the Wind Generation Plants in the National Interconnected System. Initially, it addresses the theoretical basis and the basic concept of wind energy, mainly in relation to the panorama of this renewable source in Brazil and in the world and, briefly, it also addresses the technological aspect of wind turbines. Another relevant aspect of this work is the state of the art survey on the concepts and calculations of harmonic distortions, as well as on the integration process of the new Wind Generation Plants into the basic grid. The main result obtained in this work is the sensitivity study of the harmonic distortion of voltage at the coupling point of the Central to the basic transmission network, in front of the topological variation of the collecting network of the Wind Generation Plant. For such study, a Wind Generation Plant was modeled and the methodologies studied in the state of the art were applied. The results obtained from the sensitivity study, is of great interest to the network operators and transmission of electricity, as well as to wind power generators.

A utilização da energia eólica é ainda recente no setor elétrico e, por isso, apresenta inúmeros desafios na operação e integração dessa nova tecnologia com o sistema elétrico. Desta forma, este trabalho aborda o impacto da injeção de correntes harmônicas que as Centrais de Geração Eólica geram no Sistema Interligado Nacional. Inicialmente, aborda-se a fundamentação teórica e o conceito básico da energia eólica, principalmente em relação ao panorama desta fonte renovável no Brasil e no mundo e, de uma forma sucinta, aborda-se também sobre o aspecto tecnológico dos aerogeradores. Outro aspecto relevante deste trabalho, é o levantamento do estado da arte sobre os conceitos e cálculos das distorções harmônicas, bem como sobre o processo de integração das novas Centrais de Geração Eólica à rede básica. O principal resultado obtido neste trabalho, é o estudo de sensibilidade da distorção harmônica de tensão, no ponto de acoplamento da Central à rede básica de transmissão, frente à variação topológica da rede coletora da Central de Geração Eólica. Para tal estudo, foi modelada uma Central de Geração Eólica e aplicadas as metodologias estudadas no estado da arte. Os resultados obtidos do estudo de sensibilidade, é de grande interesse para os operadores da rede e transmissão de energia elétrica, bem como às geradoras de energia eólica. / The use of wind energy is still recent in the electric sector and, therefore, presents numerous challenges in the operation and integration of this new technology with the electric system. In this way, this work approaches the impact of the injection of harmonic currents generated by the Wind Generation Plants in the National Interconnected System. Initially, it addresses the theoretical basis and the basic concept of wind energy, mainly in relation to the panorama of this renewable source in Brazil and in the world and, briefly, it also addresses the technological aspect of wind turbines. Another relevant aspect of this work is the state of the art survey on the concepts and calculations of harmonic distortions, as well as on the integration process of the new Wind Generation Plants into the basic grid. The main result obtained in this work is the sensitivity study of the harmonic distortion of voltage at the coupling point of the Central to the basic transmission network, in front of the topological variation of the collecting network of the Wind Generation Plant. For such study, a Wind Generation Plant was modeled and the methodologies studied in the state of the art were applied. The results obtained from the sensitivity study, is of great interest to the network operators and transmission of electricity, as well as to wind power generators.

Com o surgimento das novas tecnologias aplicadas aos equipamentos e arranjos geométricos das fontes renováveis de energia, o sistema de aterramento passou a operar com correntes de várias frequências, diferentes da componente fundamental. Estas correntes são provenientes das novas cargas não lineares conectadas e das condições de falta, tornando mais difícil a equipotencialização do sistema de aterramento, devido, principalmente, ao seu tamanho e sua geometria. Neste cenário, esta pesquisa tem como objetivo o estudo do comportamento de um sistema de aterramento operando na presença de correntes com distorção harmônica. Para a modelagem do sistema de aterramento teste, foi utilizada a teoria de linhas de transmissão, considerando parâmetros distribuídos, pela qual o condutor foi modelado em porções ao longo de seu comprimento. Para a modelagem e análise do sistema de aterramento foram utilizados o programa ATP (Alternative Transients Program) e uma ferramenta computacional comercial, com o intuito de validar os valores da resistência da malha de aterramento observados. Pelos resultados encontrados, têm-se argumentos para alertar os projetos futuros de sistemas de aterramento para a necessidade e uma melhor análise das situações operacionais passíveis de ocorrência no sistema elétrico que venham a apresentar uma composição harmônica diferente e não desprezível em relação ao componente fundamental. / With the rise of new technology applied to devices and geometric arrangements related to renewable energy sources, grounding systems have started to operate with currents of multiple frequencies, deviating from its fundamental component. These currents come from the connection of new nonlinear loads and fault conditions, which makes the equipotential bonding harder for the grounding system, mainly due to its size and geometry. In this scenario, this research aims to study the behavior of a grounding system operating in the presence of harmonically distorted currents. The transmission line theory was used to model the testing grounding system, based on distributed parameters, through which the conductor was modeled in increments along its length. For modeling and studying the grounding system, the ATP (Alternative Transients Program) and a commercial software tool were used in order to validate the resistance values observed in the grounding grid. Based on the results found, there are arguments to alert future grounding system projects about the need for a better assessment of operational scenarios likely to occur in the electrical system, which may display a different harmonic composition that is not negligible in relation to the fundamental component.

Diese Dissertation stellt eine neu entwickelte Methodik zur Beurteilung der Oberschwingungs-Wechselwirkung zwischen dem Netz und dem Anschlussnehmer am Netzanschlusspunkt vor. Es werden konkrete Kenngrößen zur Beurteilung der Oberschwingungs-Wechselwirkung definiert und daraufhin anhand typischer Ersatzschaltbilder für Netz- und Anschlussnehmerseite klassifiziert. Dabei werden sechs Kenngrößen für das Thévenin-Ersatzschaltbild und analog sechs Kenngrößen für das Norton-Ersatzschaltbild beschrieben. Für die Ermittlung dieser Kenngrößen aus Eingangsgrößen wird ein neuer Ansatz vorgestellt, welcher als Zusatzimpedanz-Ansatz bezeichnet wird. Der Zusatzimpedanz-Ansatz basiert auf der Variation der Spannung-Strom-Verhältnisse oder Strom-Spannung-Verhältnisse infolge des Anschlusses einer Längsimpedanz oder Queradmittanz zwischen dem Netz und dem Anschlussnehmer. Der größte Vorteil dieses Ansatzes im Vergleich zu bisher verwendeten Ansätzen ist seine Unabhängigkeit vom genauen Wert der Oberschwingungs-Äquivalenzimpedanzen. Die Methodik, die Anwendung und die Herausforderungen bei der Umsetzung dieses Ansatzes werden vorgestellt.:1 Einleitung 2 Stand des Wissens: Beurteilung der OS-Wechselwirkung 3 Systematische Definition von Kenngrößen zur Beurteilung der OS-Wechselwirkung 4 Vorstellung des Zusatzimpedanz-Ansatzes zur Beurteilung der OS-Wechselwirkung 5 Umsetzung des Zusatzimpedanz-Ansatzes zur Beurteilung der OS-Wechselwirkung 6 Leistungsfähigkeit des Zusatzimpedanz-Ansatzes im Vergleich zu bisher verwendeten Ansätzen 7 Fazit / This thesis presents a methodology for the evaluation of harmonic interaction between utility and customer at the point of common coupling (PCC). Concrete factors for the evaluation of the harmonic interaction are defined in this work. These factors are classified based on the equivalent circuits of utility and customer side for harmonic studies. In this regard, six well-defined factors for the Thevenin equivalent circuit and six analogue factors for the Norton equivalent circuit are formulated. For determining the value of these factors from input data, a new method is presented in this thesis. This method is based on the variation of the voltage-current ratios or current-voltage ratios due to the connection of a known serial impedance or parallel admittance between the utility and customer. In contrast to most previous methods, the proposed concept does not require the equivalent harmonic impedance or admittance of the utility and customer sides as input data. The methodology, application, and practical implementation issues of this method are presented in this work.:1 Einleitung 2 Stand des Wissens: Beurteilung der OS-Wechselwirkung 3 Systematische Definition von Kenngrößen zur Beurteilung der OS-Wechselwirkung 4 Vorstellung des Zusatzimpedanz-Ansatzes zur Beurteilung der OS-Wechselwirkung 5 Umsetzung des Zusatzimpedanz-Ansatzes zur Beurteilung der OS-Wechselwirkung 6 Leistungsfähigkeit des Zusatzimpedanz-Ansatzes im Vergleich zu bisher verwendeten Ansätzen 7 Fazit

Eine angemessene Qualität der Elektroenergie ist Grundvoraussetzung für den störungsfreien Betrieb aller angeschlossenen Geräte und Anlagen und spielt in den Verteilungsnetzen moderner Industriegesellschaften wie Deutschland eine zentrale Rolle. Die Elektroenergiequalität (EEQ) wird in Strom- und Spannungsqualität unterteilt. Während die Stromqualität maßgeblich im Verantwortungsbereich der Hersteller von Geräten und Anlagen liegt, sind für die Sicherung einer angemessenen Spannungsqualität im Wesentlichen die Netzbetreiber verantwortlich. Durch die technische Weiterentwicklung bspw. neuer Gerätetechnologien und die zunehmende Integration dezentraler Erzeugungsanlagen wie Photovoltaikanlagen ist zu erwarten, dass die EEQ auch künftig weiter an Bedeutung gewinnt. Die EEQ im Niederspannungsverteilungsnetz ist abhängig von Ort und Zeit und wird durch verschiedene Qualitätskenngrößen beschrieben. Die örtliche und zeitliche Abhängigkeit resultieren aus einer Vielzahl verschiedener Einflussfaktoren, welche sich entweder der elektrischen oder der nicht-elektrischen Umgebung des betrachteten Verteilungsnetzes zuordnen lassen. Die elektrische Umgebung wird durch die Art und Anzahl angeschlossener Verbraucher bzw. Erzeuger (Abnehmer- bzw. Erzeugerstruktur) sowie Struktur und technische Parameter des Verteilungsnetzes (Netzstruktur) bestimmt. Die nicht-elektrische Umgebung umfasst u.a. Einflüsse der klimatischen Umgebung wie bspw. Temperatur oder Globalstrahlung. Ziel dieser Arbeit ist die systematische Identifikation korrelativer Zusammenhänge zwischen den genannten Umgebungseinflüssen und der EEQ sowie deren Quantifizierung auf Basis geeigneter Indizes und Kenngrößen. Die Ergebnisse der Arbeit helfen grundlegende Prinzipien der Ausprägung der Elektroenergiequalität im öffentlichen Verteilungsnetz besser zu verstehen sowie die Verteilungsnetze im Hinblick auf die Elektroenergiequalität zu charakterisieren und zu klassifizieren. Analog zu den Standard-Lastprofilen erfolgt die Definition von Standard-Qualitätsprofilen. / Power quality levels in public low voltage grids are influenced by many factors which can either be assigned to the electrical environment (connected consumers, connected genera-tion, network characteristics) or to the non-electrical environment (e.g. climatic conditions) at the measurement site. Type and amount of connected consumers (consumer topology) are expected to have a very high impact on power quality (PQ) levels. The generation topology is characterized by number and kind of equipment and generating installations like photovoltaic systems which are connected to the LV grid. The electrical parameters of the grid define the network topology. The parameters which are most suitable to describe each of the three topologies and the climatic environment will be identified. Voltage and current quality in public low voltage (LV) grids vary depending on location and time. They are quantified by a set of different parameters which either belong to events (e.g. dips) or to variations (e.g. harmonics). This thesis exclusively addresses continuous parameters describing variations. Continuous phenomena like harmonics are closely linked to an one-day-cycle which implies a more or less periodic behavior of the continuous power quality parameters. Consumer topologies such as office buildings or residential areas differ in their use of equipment. Time series analysis is used to distinguish between different consumer topologies and to identify characteristic weeks. The clustering of one-day time series is applied to identify characteristic days within the weeks of certain topologies. Based on the results, emission profiles for certain current quality parameters of different consumer topologies will be defined. Due to the characteristic harmonic current emission of certain consumer topologies which represents the typical user behaviour a classification system is developed. It is used to automatically classify the emission profiles of harmonic currents for unknown measurements and to estimate a likely consumer topology. A classification measure is introduced in order to identify unusual or false classified emission profiles. The usage behaviour of equipment by customers usually varies over the year. Subsequently, the levels of PQ parameters like harmonics may show seasonal variations which are identified by using newly defined parameters. The introduction of new device technologies on a large scale like the transition from incandescent to LED lamps might result in long-term changes to the levels of PQ parameters (e.g. harmonics). The analysis of the long-term behavior (trend) will be applied in order to quantify global trends (looking on the measurement duration as a whole) and local trends (looking on individual segments of the whole time series).

Eine angemessene Qualität der Elektroenergie ist Grundvoraussetzung für den störungsfreien Betrieb aller angeschlossenen Geräte und Anlagen und spielt in den Verteilungsnetzen moderner Industriegesellschaften wie Deutschland eine zentrale Rolle. Die Elektroenergiequalität (EEQ) wird in Strom- und Spannungsqualität unterteilt. Während die Stromqualität maßgeblich im Verantwortungsbereich der Hersteller von Geräten und Anlagen liegt, sind für die Sicherung einer angemessenen Spannungsqualität im Wesentlichen die Netzbetreiber verantwortlich. Durch die technische Weiterentwicklung bspw. neuer Gerätetechnologien und die zunehmende Integration dezentraler Erzeugungsanlagen wie Photovoltaikanlagen ist zu erwarten, dass die EEQ auch künftig weiter an Bedeutung gewinnt. Die EEQ im Niederspannungsverteilungsnetz ist abhängig von Ort und Zeit und wird durch verschiedene Qualitätskenngrößen beschrieben. Die örtliche und zeitliche Abhängigkeit resultieren aus einer Vielzahl verschiedener Einflussfaktoren, welche sich entweder der elektrischen oder der nicht-elektrischen Umgebung des betrachteten Verteilungsnetzes zuordnen lassen. Die elektrische Umgebung wird durch die Art und Anzahl angeschlossener Verbraucher bzw. Erzeuger (Abnehmer- bzw. Erzeugerstruktur) sowie Struktur und technische Parameter des Verteilungsnetzes (Netzstruktur) bestimmt. Die nicht-elektrische Umgebung umfasst u.a. Einflüsse der klimatischen Umgebung wie bspw. Temperatur oder Globalstrahlung. Ziel dieser Arbeit ist die systematische Identifikation korrelativer Zusammenhänge zwischen den genannten Umgebungseinflüssen und der EEQ sowie deren Quantifizierung auf Basis geeigneter Indizes und Kenngrößen. Die Ergebnisse der Arbeit helfen grundlegende Prinzipien der Ausprägung der Elektroenergiequalität im öffentlichen Verteilungsnetz besser zu verstehen sowie die Verteilungsnetze im Hinblick auf die Elektroenergiequalität zu charakterisieren und zu klassifizieren. Analog zu den Standard-Lastprofilen erfolgt die Definition von Standard-Qualitätsprofilen. / Power quality levels in public low voltage grids are influenced by many factors which can either be assigned to the electrical environment (connected consumers, connected genera-tion, network characteristics) or to the non-electrical environment (e.g. climatic conditions) at the measurement site. Type and amount of connected consumers (consumer topology) are expected to have a very high impact on power quality (PQ) levels. The generation topology is characterized by number and kind of equipment and generating installations like photovoltaic systems which are connected to the LV grid. The electrical parameters of the grid define the network topology. The parameters which are most suitable to describe each of the three topologies and the climatic environment will be identified. Voltage and current quality in public low voltage (LV) grids vary depending on location and time. They are quantified by a set of different parameters which either belong to events (e.g. dips) or to variations (e.g. harmonics). This thesis exclusively addresses continuous parameters describing variations. Continuous phenomena like harmonics are closely linked to an one-day-cycle which implies a more or less periodic behavior of the continuous power quality parameters. Consumer topologies such as office buildings or residential areas differ in their use of equipment. Time series analysis is used to distinguish between different consumer topologies and to identify characteristic weeks. The clustering of one-day time series is applied to identify characteristic days within the weeks of certain topologies. Based on the results, emission profiles for certain current quality parameters of different consumer topologies will be defined. Due to the characteristic harmonic current emission of certain consumer topologies which represents the typical user behaviour a classification system is developed. It is used to automatically classify the emission profiles of harmonic currents for unknown measurements and to estimate a likely consumer topology. A classification measure is introduced in order to identify unusual or false classified emission profiles. The usage behaviour of equipment by customers usually varies over the year. Subsequently, the levels of PQ parameters like harmonics may show seasonal variations which are identified by using newly defined parameters. The introduction of new device technologies on a large scale like the transition from incandescent to LED lamps might result in long-term changes to the levels of PQ parameters (e.g. harmonics). The analysis of the long-term behavior (trend) will be applied in order to quantify global trends (looking on the measurement duration as a whole) and local trends (looking on individual segments of the whole time series).